impressions of the 1956 stockholm congress of the international society of photogrammetry

PHOTOGRAMMETRIA Nr. 1

Impressions of the 1956 Stockholm Congress of the International Society of Photogrammetry

by

W. S C H E R M E R H O R N , Delft, Holland.

1. Introduction.

Although it is a t empta t ion to me to compare my f i r s t in ternat ional conference on photogrammetry , now exact ly 30 years ago, with the s i tuat ion in pho togrammet ry as shown on the In ternat ional Congress in Stockholm, I will not repeat the historical review I gave in my article about the impress ions of the 1952 Wash ing ton Congress in this review [1]. One of the g rea te s t d i f ferences is wi thout any doubt t ha t the Stockholm con- fe.rence was really in ternat ional : 41 countr ies were represented ei ther as a member country or by guests . This proves t ha t pho tog rammet ry nowadays is accepted and recog- nized all over the world as a normal survey technique. I t m a y be tha t m a n y of these countries only contributed to the conference by their presence and by the part icipat ion of their representa t ives in personal discussions, but this is due to the ra ther recent esta- bl ishment of photogrammetr ic services in several of these countries. We therefore expect t h a t on the next Congress m a n y of these countries will par t ic ipate not only in a passive way, but also more actively by p resen t ing nat ional i~eports contr ibut ing to Commission reports and by papers. This will have consequences for the organizat ion of the next congress as I will explain in the las t pa rag raph .

2. Organization and character of the Stockholm Congress.

Our Swedish colleagues have done their u tmos t to organize the Congress in such a way tha t a sa t i s fac tory discussion and exchange of views could take place. Their aim has been to publish papers in advance and to make the repor ts of the commissions available to all par t ic ipants before the congress. In order to reach this aim the Swedish Bureau of the In ternat ional Society announced a s t r ic t t ime table for all technical communications and required summar ies of all papers before the 1st of March 1956. These summar ies reached several of us, in par t icu la r in the European countries, in t ime to be studied before the Congress. F rom this point of view the Swedish organizat ion was an impor tan t improvement compared with previous congresses. Each par t ic ipant of the Congress could now obtain some impression about the subject of the papers and sometimes prepare h imsel f in the few weeks or days left before his depar ture for Stockholm. We, in the ITC, for instance have been most g ra te fu l to our Swedish f r iends for this, because bl this way we were able to organize a p repa ra to ry discussion of congress subjects in a one week's summer course j u s t before the conference.

The set-up regard ing the detailed mater ia l provided to the congress in the form of repr in t s of art icles was less succesful. These repr in t s were required three months in advance, but could not be distr ibuted amongs t the par t ic ipants before the Congress. This was done dur ing the Congress and each of the par t ic ipants had to fo rward by special marl a heavy load of paper f rom Stockholm to his home country wi thout hav ing the chance for a p r o p e r ' s t u d y of these papers.

A fu r t h e r consequence of th is change in organizat ion was the al terat ion in the publication of the In te rna t iona l Archives for which the Swedish Congress Bureau as such has taken the init iat ive ~ d the responsibility. The intention was to organize the publicat:on of the Archives in such a way t h a t a two years ' delay could be avoided. It is t rue tha t this delay was a g rea t d isadvantage of the method applied in the past . Therefo e the, Congress Bureau decided to dis t r ibute a t the Congress volume II and III containing the

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national reports and the reports of the seven technical commissions. Fur thermore we received in a s t i ff cover all loose reprints which form Pa r t IV of the Archives. This cover however cannot be used by libraries or institutions and by many private persons and they are obliged to order a more costly binding than required for the previous volumes. Still greater is the disadvantage tha t in the pa r t containing the papers no continuous numbering of the pages will be made. This makes the use more difficult than of previous volumes.

In conclusion we find tha t only the publications of the summaries which will be included with the records of the meetings in pa r t I of vol. XII are a real improvement. This cannot be said of the other changes in the method of publication of the International Archives. We believe tha t in the future such changes in the method of publication of the Archives can only be allowed af te r an authorisation of the general assembly of the ISP.

Other characterist ics of this Congress were the enormous number of papers, part ly read by title and the almost complete lack of a real discussion. Many of the highly specialized subjects, such as for instance problems of adjustment of aerial triangulation, could perhaps have been discussed if, f i r s t of all, more time had been available for explanation of the paper and secondly if the audience had been much smaller and consisting only of those really interested in this part icular subject. Now the whole climate of the commission meetings was such that discussions could only be very brief and not thoroughly enoug h. This was the contrary to the experience we gained in the ITC's second summer course week, which was used for a thorough discussion of the most important subjects of the Congress. There was a possibility for the discussion which should have taken place in many of the commission meetings. The difference, however, was that in this one week's course the number of subjects was limited to the most important items from the Congress in Stockholm.

A fur ther characterist ic is that for the f i r s t t ime the Congress of the ISP was attended by guests from behind the iron curtain. There was quite an important delegation from Russia and Poland. Although these guests were not announced in advance the Congress Bureau gave the Russian delegation the chance to make a few communications which, however, came not fa r above general remarks; the audience learned nothing that was not already known from recent publications de'dyed directly from Russian sources. In a private conversation, however, one of the leading Russian representatives supposed that perhaps during the next conference in London the Russian delegation would be able to speak not only in general terms, but above all to show instruments and work used in tha t country. This time the benefit of the participation of the guests was more on the Russian side than on tha t of the member countries.

The organization of the Congress was made very difficult to our Swedish friends by the fact that so many members of the Congress did not announce their par t ic ipa t ion at all or at the last moment. The number of par t ic ipants was much larger than expected in advance.

3. Comm. I. Photography.

As a general remark it must be stated that in the field of navigation, f l ight planning and flight operations only few presentations of importance were made. Worse perhaps was the lack of the products of the American industry in this commission. In part icular the absence of the new American cameras of Fairchild with Bausch and Lomb Planigon Lens left a gap in the remarkable exhibit of the mainly European firms.

The important new features were the Wild-Bertele super wide-angle lens, which combined a large angle of field with an excellent quality of the image (the Super Avio- gon). There were as new creations an improved Ross lens and the Zeiss wide-angle Pleogon lens, competitors of the now already famous Wild-Bertele Aviogon, which was present together with the Wild-Bertele Aviotar in cameras RC5, RC7, RC8 and with the well-known Zeiss Topar s tandard angle lens. There is no doubt tha t these latest develop-

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ments in lens design s ignify a g rea t step forward in the general qual i ty of photographic images.

The expression of image qual i ty by means of the definition of resolving power, resolution or sha rpness becomes more and more doubtful , no twi ths tand ing the general use of these in photogrammetry . The resolution is a very weak description of w ha t happens in image format ion and in h u m a n vision. We draw the a t tent ion to the work presented by Inge l s t amm on cont ras t t r ansmiss ion and contras t ]'eduction values in image formation. In this impor tan t work the modern t rend of def in ing " sha rpness" in a physical- mathemat ical way is demonstrated. Pe rhaps tha t by fu r t he r development along this line it will be possible to create new means to express image qual i ty and t hus come to a more objective comparison of the qual i ty of photogrammetr ic cameras as used nowadays.

Regard ing these photographic quali t ies of images we m u s t bear in mind tha t photographic mater ia l s and techniques show nowadays a bet ter resolution with a g rea te r speed than those available 10-20 years ago. A g radua l progress ha s been made since. Our per- s.onal experience in var ious pa r t s of the world gives us the impression t ha t the difficulties in air photography do not arise f rom lack of good mater ia l , bu t more f rom a lack of well-trained s t a f f and personnel. In several organizat ions a i r photography is not t reated as a science, but more like a chemical handicraf t . There is an enormous discre- pancy between the high scientific s t andard of the factories of photographic mater ia l s and tha t of the organizat ions who use these mater ia ls .

Regard ing photographic mater ia l s the question film versus plate remained unsolved. The number of complications increases on both sides. The difficulties with f l a tness of glass plates become more and more known and a recent s tudy in the Bri t ish Photogram- metric Record [2] draws the a t tent ion to the influence of the flexion of the plate under the influence of its own weight. This, however, is a theoretical s tudy because the tensions of the negat ives in their f r ames will remain d i f ferent f rom those assumed by this author. There are moreover resul ts , which cause a preference for g lass plate negat ives and others which show no impor tan t difference. The Stockholm Congress has left this problem in entirely the same position as before. Pe rhaps f rom the invest igat ions under way we ma y expect a clarification of th is problem in a not too d is tan t fu ture .

We consider as impor tan t the new electronic scann ing spot pr inter . This was shown for the f i r s t t ime and will enable improvement of image representa t ion in m a n y cases. The creation was announced of the USA Log Etronic and of the Cintel I n s t rume n t made by Cinema-Television Ltd., in England. The Engt ish prototype was shown; of the Ame- r ican in s t rumen t s only the technical da ta were available, bu t the i n s t rume n t itself was not exhibited.

Regard ing enlargers , rectifiers, reduction pr in te rs etc. we have to mention the Zei~s SEG ¥ Rectif ier and the Wild En l a rge r VG I. The importance of both i n s t rumen t s lies in the fact t h a t the lenses used in these reproductio n i n s t r u m e n t s are adapted to the modern s t andards of precision and image qual i ty of the modern cameras of the same f i rms. It h a s no sense to use a h igh qual i ty Pleogon or Aviogon lens to spoil a f t e rwards the resul ts in an enlarger or rect if ier which has a lens of a much lower quality. With such a combination a mosaic for ins tance can never be up to s t andard no twi ths tand ing the h igh qual i ty of the negatives.

The reduction pr inters , such as those of Zeiss and Wild (which could be better called " t ransfo l 'ming pr in te rs" ) will become more and more important . Their funct ion is not to ]'educe, but to ca r ry out a t r an s fo rma t ion of the original photograph into another, in order to make res t i tu t ion more independent f rom sizes, principal distances and dister- sions of the air camera. A demand made upon th is t r a n s f o r m i n g pr in te r is t ha t it should fulfill very s tr ict specifications regard ing mechanical and optical precision. In this section Nistr i presented his telescopic pr in ter- rect i f ier which is a t r a n s f o r m i n g pr inter , act ing a t the same t ime as rectifier. This i n s t r u m e n t ma y be used in such cases where the elements of camera orientat ion are obtained with suff ic ient reliability by means of

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a gyroscope o r horizon picture. The production of such diapositives can be impor tan t if we prefer res t i tu t ion of our photographs in a th i rd-order approximate plot t ing ins t rument (see our discussion of this subject under Comm. II).

Regard ing the determinat ion of camera orientat ion at the moment of exposure there was not much news of Spectacular character . "A new method, introduced by Pa lmer and developed in Canada, de termines the s t r ip bendings in az imuth by means of forward oblique inf ra red photography. I t is a kind of forward alignmen~ in successive obliques. (See our discussion about commission III.)

Other methods such as Shoran, Hiran , Decca, a irborne profile recorder (APR) statoscope and gyroscope are gradua l ly being improved.

I believe, however, t ha t it is doubtful whether this improvement can also be obtained for the gyroscope. In this respect I consider it necessal W to make a few remarks regarding this subject. Dur ing the 10 years since the war , m a n y e f for t s have been made to develop the gyroscope to a reliable precision i n s t rumen t which can solve the problem of orientat ion of the camera. Everybody knows t h a t this, if it could be realized, would be of the u tmos t importance for photogrammetry . We could make a direct use of tilt and tip in rect ifying, as well as improve the accuracy of radial t r iangula t ion with these values or use them for l imit ing the propagat ion of errors in aerial t r i angula t ion in space. We all expected tha t this powerful tool would be made available. One of the resul ts of this expectation was t ha t no more at tent ion was paid to the pre-war means used for the same purpose, in par t icu la r the horizon camera. The resul t is t ha t only in the count ry in which the cradle of this horizon camera s tands (Fin land) the use of it has been fu r t he r developed. The succesful use of the same inst~mment in the Nether lands became impossible because of the loss of all Zeiss cameras with horizon dur ing the w a r [3]. We believe tha t it has now become an u rgen t problem to take up aga in the horizon camera and develop it together with the Santoni Solar Periscope as the most reliable and precise means for the dete~mination of the elements of orientat ion dur ing exposure. F u t u r e exper iments will show which of these two available tools is the best, i.e. which is the easiest to handle, the most reliable and which gives t h e mos t precise results. We hope tha t in this respect the next congress will show a g rea t improvement . The f i r s t step would be to convince the f~ctories of the g rea t importance of the horizon picture, in par t icu la r for aerial t r iangulation. With some al terat ion of the pre-war type it m igh t even be extended in such a way tha t also the Pa lmer az imuth control of a s t r ip could be obtained with the same horizon camera.

The resolutions proposed by Comm. I and accepted by the General Assembly as f a r as they are of a technical na tu re have s tressed in No. 5 the desirabil i ty to extend the tests on regis t ra t ion of the horizon to some countr ies which have no experience so far . It is impor tan t therefore tha t some fac tory t a k e s ' u p aga in the task to build a good horizon camera it/ order to enable those who believe in i ts value to fulfill the wish expressed in point 5 of the resolutions.

4. Comm. II. Instruments and methods of restitution.

In Comm. II we can dis t inghuish between var ious subjects. 1. Announcement of new ins t ruments . 2. Determinat ion of precision and ana lys i s of e r rors of ins t ruments . 3. Problems about relative and absolute orientation.

Regard ing new ins t rumen t s we mus t admi t tha t the ha rves t is r a the r poor. There were papers about the Photostereograph Nis t r i Beta II and the Stereotop of Zeiss. These, however, are not new because they were already exhibited in Washington , a l though it mus t be borne in mind tha t the Stereotop was subs tan t ia l ly redesigned and tha t also the Nistr i Beta II is improved compared to the 1952-model. The same holds good for several other ins t ruments , even for the f i rs t -order machines of the classical type. I have some- t imes the impression t ha t with our plot t ing machines we go the same way as with auto-

mobiles which every year show so-called improvements , bu t which, f r o m the technical point of view are complications. Ano the r compar ison can be made wi th a m a t e u r cameras which are r egu la r ly improved in such a w a y tha t a no rma l use r has so m a n y tr icks on his camera, t ha t only in exceptional cases he can use it. The only fact which a lways counts is the increase in price.

Are we going the same w a y with ou r p lot t ing machines? Modern techniques can make better i n s t rumen t s for less money. Ins tead of this, these techniques a re used to add new auxi l iary i n s t r u m e n t s to the exis t ing types, keeping the i n s t r u m e n t s at best on the same price, bu t sometimes make them more expensive. I believe t ha t a be t te r solution would be to s implify the i n s t r u m e n t s as much as possible and make them avai lable at a more reasonable price.

I t m a y be t ha t some designers of the i n s t r u m e n t s and even some vis i tors of the exhibits, who have admired the ingenuous new tools on the i n s t r u m e n t s cannot apprecia te these r e m a r k s too well. I m u s t admi t t h a t n a t u r a l l y they are not t r u e fo r all addit ional tools, because some of them have a g r ea t influence on th~ efficiency of the i n s t r u m e n t and pa r t ly on the reliabil i ty of the results . The reg i s t ra t ion of the coordinates is an example of an essential improvement , the value of which is mos t a p p a r e n t on the Stereotopographe Poivill iers type B., wi th the r ead ing of the coordinates on long verniers a t an uneasy place in the older models. The mechanical coordinate reg i s t ra t ion of the Zeiss C8 w a s shown; it seems however, tha t in the nea r f u t u r e not only in the Wild A7 will it be possible to connect its recording device wi th a punched card pr in te r , bu t also in the Zeiss C8. These are improvemen t s which cost quite some money, bu t which have a favourable influence on the efficiency of the ent ire pho tog rammet r i c p lo t t ing procedure. We believe however, t ha t th is comput ing sys tem is also still in its ear ly beginning. So

f a r we used only the no rma l IBM punched card computers . I t is an open question whe the r the day will come tha t wi th an increased product ion of f i r s t -o rde r p lot t ing machines and an increased appl icat ion of the ent i re ly analyt ical method in pho tog rammet ry , a special comput ing machine will be designed which is in pa r t i cu la r a d a p t e d to pho tog rammet r i c work and specially suitable fo r combinat ion wi th a f i r s t -o rde r machine. We unde r s t and however, t h a t so f a r the use of conventional types which have a much l a rge r market , is the cheapest solution for pho tog rammet r i s t s .

My critical r emark , however, is much more directed t o w a r d s ano ther e lement which is introduced now: the t r ansmis s ion devices. So f a r we have main ly mechanical t r a n s - missions. We change the elements of or ienta t ion ~ and w and the base components by means of screws and w o r m wheels which are moved by f ree hand. At the exhibit ion we have seen applicat ions of electro-mechanical devices. Nis t r i s tar ted, as we know, wi th the electrical t r ansmiss ion and he has applied now the same principle to his model Beta I I in such a way tha t the scann ing movement is changed into the opera t ion of the s teer wheel like in a car. Wild has a kind of column control fo r the scanning movement on the A7 which is handled in a s imi lar w a y as the control column of an airplane. It. seems, however, t h a t this increases the price of the A7 wi th an a m o u n t of someth ing like Sw. Fr . 20.000.-- I doubt very much w he t he r th is kind of " improvemen t " can ever be just i f ied f rom an economic point of view. I f I then see t ha t fac tor ies in the i r o f f e r s to countries, in which main tenance of i n s t r u m e n t s as such is a l ready a problem, p ropaga t e all these remote control devices as improvements , I doubt whe the r it is real ly r igh t to introduce in services, which are f a r away f rom the factory , such elements which make the ins t ru - ment more vulnerable and increase the chance t ha t it will be out of order. Al ready the electrical r eg i s t ra t ion of coordinates is difficult, enough. I do not th ink tha t by mak ing the i n s t r u m e n t s in this direction still more complicated we would render a g rea t service to m a n y inst i tutes , nor do I consider it necessary. Al though the movement of b z and b v

by f ree hand in the S te reop lan ig raph requi res some time, I prefer , f r ank ly speak ing , for the use in an overseas country, the "old fash ioned" C8 above the C8 with all these

improvements which are j u s t as m a n y weak spots. I f such a remote control is an essen-

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tial element in the design of i n s t l umen t s such as the van i sh ing point control by electric drive on the Zeiss SEG V Rectifier, I can fully agree and I believe we m u s t take the risk. If, however, it is only to avoid the f reehand movement of a bx-handwheel , we go too fa r because we replace an operation which does not cost very much, by a risk. This does not count if we keep s imul taneously on the in s t rumen t s the t radi t ional possibilities for the movements, but then the new elements will certainly have an increasing influence on the price. I fully reMize as I said before, t ha t not everybody will agree with these remarks which have the tendency t ha t in the design of i n s t rumen t s we m u s t d is t inghuish between tools and toys. I accept the risk to he considered an old-fashioned photogrammetr i s t . The background of my thoughts is only t h a t we mus t put in the hands of the m a n y n~w photogrammetr ic services with an enormous number of hard ly t ra ined operators ins t ruments which are as simple as possible and which have no more complications than necessary for an efficient solution of the problems.

Regard ing in s t rumen t s of the Multiplex and Kelsh types, we found t h a t Nis t r i has replaced his Fotocar tografo IV by No. V which m e a n s t ha t Nis t r i has abandoned the advantage of observation on the screen in the direction of the project ing r ays and now observes reflected images f rom a white painted screen like all Multiplex and s imilar ins t ruments . Also f rom other points of view we believe t ha t the Fotocar tografo V is another type t h an the Fotocar tograf0 IV. To a certain extent V is a simplification of IV, al though also in this i n s t r u m e n t we find, like in the Will iamson LSP, the tendency to add all kinds of complications to the original simple type of Kelsh plotter wi thout chang- ing any th ing in the fundamen ta l l imitation of the capaci ty of th is i n s t rume n t which lies in its sys tem of observation of wha t is sometimes called "dull-s ighted" images. We believe tha t the Kelsh plotter mus t be kept as simple as possible because th is is the grea t advan tage of th is type of ins t rument .

F rom tha t point of view I can accept the Gamble Plot ter as a real improvement on the mult iplex i n s t rumen t s as f a r as they are not used for bridging. The Gamble Plotter

which projects a network of dots directly on the map sheet, gives the possibility to draw contour lines by free hand directly on the map. We believe this m u s t considerably improve the efficiency of plotting. This is a kind of improvement in one of the essential elements of the operation of an i n s t rumen t and therefore the little complication of the device for projecting the grid of dots is ful ly acceptable.

In the series of f i rs t -order i n s t rumen t s consis t ing (in alphabetical order) of the well-known Galileo-Santoni Stereocartografo IV, SOM-Poivilliers Stereotopographe Type B, Wild Au tog raph A7 and Zeiss Stereoplanigraph C8 we m u s t add Nis t r i ' s Fotostereo- g raph Beta II which ha s now found i ts definite form. Still more just i f ied to be considered a really new type is the Thompson W a t t s Plotter which was shown for the f i r s t t ime to an in ternat ional public a t th is conference. Both thes~ new in s t rumen t s use the Porro- Koppe system but above all the Thompson Wa t t s Plotter is based on a principle of design which is entirely d i f ferent f rom all exis t ing ins t ruments . We do not consider it necessary to go here into f u r t h e r details [4].

A special position is held by the new Autograph Wild A9. The design of th is ins t ru - ment became necessary because none of the exis t ing f i rs t -order machines can take photo- g raphs f rom the Super Aviogon lens. This A9 mus t wi thout any doubt be considered as a f i rs t -order plott ing ins t rument , no twi ths tand ing the fact t ha t the in s t rumen t takes only photographs of ha l f the original size. This au tograph m u s t therefore be used in combination with the Wild U3 t rans fo rmer . Because of this necessi ty it will be preferable to put correction plates for distort ion in th is t r a n s fo rme r and work in the A9 with distort ion-free diapositives. This makes it unnecessa ry to use in the i n s t rume n t i tself a pair of compensat ing plates which, due to the reduction of the size, would require twice the precision of the normal compensat ing plates.

The new Wild A9 Autograph not only takes photographs made with the super wide angle, bu t also with all kinds of normal wide-angle cameras. }~ecause the r ange of prin-

cipal d i s t ance is be tween 40 and 77 m m , the A9 does no t t ake the n o r m a l s t a n d a r d ang le p h o t o g r a p h s w i th p r inc ipa l d i s t ance s l a r g e r t h a n 150 m m . (We do no t cons ider a 3 X reduct ion o f the n e g a t i v e s in o rde r to become a p r inc ipa l d i s t ance s m a l l e r t h a n "/7 m m as a n acceptable solut ion. ) The A9 is a good e x a m p l e of the p r e s e n t t endency to c r ea t e i n s t r u m e n t s for special pu rposes . W e believe t h a t in f u t u r e the i m p o r t a n t p h o t o g r a m - met r ic serv ices will have a t t he i r d i sposa l a c e r t a i n v a r i e t y of i n s t r u m e n t s o f wh ich each is adap t ed to the solut ion of a special problem.

A n o t h e r new i n s t r u m e n t is t he SOM-Baboz Stereophot . I t is a second-orde r p lo t te r wi th l imi ted precis ion. I t is second o rde r because i t rea l izes geome t r i c a l l y speak ing , a pe r fec t solut ion. T he a i m of th i s i n s t r u m e n t is to s imp l i fy the s y s t e m of obse rva t ion to a type of f ixed m i r r o r s tereoscope. T h e r e f o r e a f l o a t i n g m a r k in t he f o r m of a l i gh t spot is p ro jec ted in t he p l ane o f t he nega t ives . T h i s p ro jec t ion is c a r r i ed ou t in a d i f f e r e n t w a y t h a n in the K u y p e r s L i g h t Spot P lo t te r , bu t the u se of th i s p r inc ip le of p r o j e c t i n g a l ight spo t in t he p lane of t he nega t ive , wh ich goes back to P r 6 d h u m e a u in 1926, bo th i n s t r u m e n t s h a v e in common. The S te reopho t combines th i s idea w i th a m e c h a n i c a l pro- jec t ion and the K u y p e r s P lo t t e r w i t h an opt ica l project ion. Baboz found an i n g e n u o u s solut ion fo r t h e i n t roduc t ion of the e l emen t s o f re la t ive o r i en t a t i on by m e a n s of ro ta t ion of a sma l m i r r o r , t he c en t r e o f ro t a t ion of the col l imators . A w e a k n e s s o f t h i s i n s t r u - m e n t is t h a t so f a r t he s tereoscope h a s on ly two t i m e s e n l a r g e m e n t . We believe th i s e n l a r g e m e n t is d e t e r m i n e d by t he size of the l i gh t spo t in t h e p l ane o f the nega t i ve , wh ich is t he in te r sec t ion of t h i s p l ane w i t h a bund le of pa ra l l e l l i gh t c o m i n g f r o m a l i gh t source in the focal p l ane of t h i s col l imator . I t m a y be t h a t t h i s sma l l m a g n i f i c a t i o n l im i t s the possibi l i t ies of app l i ca t ion o f th i s r e m a r k a b l e i n s t r u m e n t .

The solut ion o f the p rob l em of t h i r d - o r d e r i n s t r u m e n t s s eems to be r a t h e r d i f f icu l t . Th i s can be der ived f r o m the f a c t t h a t no n e w so lu t ions fo r th i s p rob lem were shown in Stockholm. T h e r e were a g a i n t he Z e i s s Stereotop, the N i s t r i Model 90 S t e r e o g r a f o m e t e r a n d Gal i l eo-Santon i C a r t o g r a p h i c S t e r eomic rome te r . Much a t t e n t i o n h a s been paid to these i n s t r u m e n t s d u r i n g t he exhibi t ion. T h a t is for obvious r e a s o n s : m a n y i n s t i t u t e s , which need a g r e a t n u m b e r of i n s t r u m e n t s mee t d i f f i cu l t i e s w i t h t he cost of i n v e s t m e n t , l~ecessary even fo r second-order mach i ne s . T h e y a r e all w a i t i n g for t h i r d - o r d e r p lo t t i ng i n s t r u m e n t s wh ich can be b o u g h t a t a r e a sonab l e price. W e h a v e the impress ion , however , t h a t the v a r i o u s so lu t ions of t h i s p roblem, wh ich so f a r a r e no t more t h a n p ro jec t s on paper , will come as f a r a s t he i r p r ices a r e concerned, too close to t he s i m p l e s t possible vers ion of a Ke l sh P lo t te r . T he cost o f t he e x i s t i n g t h i r d - o r d e r i n s t r u m e n t s ( t h i rd -o rde r because of the a p p r o x i m a t e solut ion by i t) wh i ch lies be tween P o u n d S t e r l i ng 800 and 1000 m a y be reasonab le , b u t is st i l l a l a r g e a m o u n t of money . These i n s t r u m e n t s , however , can in m a n y cases r e n d e r exce l len t services . I t would be des i rable , t h a t a comple te t h e o r y of t hese i n s t r u m e n t s were be pub l i shed in o rder to de t e rmine t he i r l imi ta t ions . T h e y a r e not u n i v e r s a l a n d i t i s we l l -known t h a t a combina t ion of a cons ide rab le t i l t o f the opt ical ax i s of abt . 3 degrees and l a r g e d i f f e r e n c e s in h e i g h t in t he t e r r a i n can cause e r r o r s in h e i g h t Which a r e f a r above t he n o r m a l to le rances . We believe, however , t h a t t he use of these i n s t r u m e n t s will become still more gene ra l and t h a t t he i r p r e s e n t l imi t a t ion can be overcome as soon as we can der ive the t i l t f r o m for i n s t ance hor izon p i c tu re s a n d as soon as we h a v e a u n i t r ec t i f i e r a t ou r d i sposa l wh ich p rov ides u s w i t h d iapos i t ives or pr in t~ on n o n - s h r i n k a b l e m a t e r i a l on t he scale of the o r ig ina l nega t ive , b u t wh ich a re rect i f ied. Here a g a i n we mee t a r ea son w h y the cons t ruc t ion of a good hor izon c a m e r a is one of the mos t u r g e n t needs in p h o t o g r a m m e t r y .

T h a t t he s te reoscopic obse rva t ion is st i l l a con t inuous sub jec t of s t u d y and e f f o r t s for i m p r o v e m e n t w a s p rov ided by the p a p e r s a t t h i s congress . The m o s t i m p o r t a n t was p e r h a p s t h a t of Mr. Y z e r m a n , " t he SDI, a new me thod for s tereoscopic m e a s u r e m e n t s

and p lo t t i ng" , a m e t hod of obse rva t ion developed by Mr. Y z e r m a n d u r i n g his period of

s t u d y a t t he ITC on a Ke l sh P lo t t e r . H i s me t hod p romi se s a prec is ion which a h ' e a d y in

8

t h e o r y is twice t h a t of the n o r m a l s tereoscopic obse rva t ion . Mr. Y z e r m a n p roved in h i s

p r e s e n t pos i t ion in the K e r n f ac to ry , in Swi tze r l and , t h a t he ob ta ined on an i n s t r u m e n t of t he m i r r o r s t e reoscope- type a n a v e r a g e decrease o f the m e a n s q u a r e e r r o r in h e i g h t of 50% by m e a n s of h i s Stereo Di rec t I n v e r s e equ ipmen t . We cons ider t he app l i ca t ion of th i s p r inc ip le of s u f f i c i e n t i m p o r t a n c e to c a r r y ou t f u r t h e r e x p e r i m e n t s in t h i s direct ion. Espec ia l ly for the M ul t i p l ex - t ype of i n s t r u m e n t s t h i s could be of impor t ance , a l t h o u g h he re i t is also t r u e t h a t the addi t ion of an e lec t r ica l device m a k e s the i n s t r u m e n t m o r e vu lnerab le . F u r t h e r m o r e we d r a w the a t t e n t i o n to an i m p o r t a n t ar t ic le by P ro f . Baets l6 f r o m Be lg ium r e g a r d i n g t h e a p p a r e n t e x a g g e r a t i o n of t h e re l ie f in s tereoscopic obser- vat ion. He comes to t h e conclus ion t h a t coopera t ion o f p h o t o g r a m m e t r i s t s and phys io log i s t s is n e c e s s a r y in o rde r to come to a b e t t e r solut ion t h a n a t p resen t .

R e g a r d i n g the second g r o u p of sub jec t s " T h e d e t e r m i n a t i o n of prec is ion and a n a l y s i s of e r ro r s of i n s t r u m e n t s " on ly a f ew p a p e r s were p resen ted . In t h e Geodetic I n s t i t u t e of the U n i v e r s i t y of Mi lan a s i m i l a r r e s e a r c h as c a r r i e d ou t by v. d. Weele in De l f t d u r i n g t he w a r on two s t e r e o p l a n i g r a p h s , w a s pub l i shed fo r a San ton i S t e r e o c a r t o g r a f o IV. In the conclus ion t he a u t h o r s g ive p rov i s iona l va lue s of the m e a n pro jec t ion e r r o r s ob ta ined f r o m t e s t s conduc ted d u r i n g p l o t t i n g m~ = 6 ~ my = 4 ~, ml~ = 0.080/00 of t he f l y ing he igh t . I t is r e g r e t t a b l e howeve r , t h a t t hey do no t ind ica te w h a t k ind o f p lo t t i ng th i s h a s been, w h e t h e r it is a c e r t a i n t y p e of p h o t o g r a p h y or w h e t h e r it is the p lo t t ing Gf gr ids , wh ich m a k e s a g r e a t d i f fe rence . The f i g u r e s g ive me t h e i m p r e s s i o n t h a t t h e y a r e der ived f r o m g r i d m e a s u r e m e n t s .

Severa l Swedish pub l i ca t ions a re based on t he m e t h o d s as descr ibed by H a l l e r t fo r t h e d e t e r m i n a t i o n of r ad i a l d i s tor t ion . H a l l e r t and R a i n l u n d m a k e a s u g g e s t i o n for a s t a n d a r d i z e d t e s t of t he p ro jec t ion s y s t e m in p h o t o g r a m m e t r i c p lo t t i ng i n s t r u m e n t s in wh ich t h e y also e x p r e s s t he e r r o r s of p ro jec t ion in a k ind of r ad ia l d i s to r t ion curve . A f t e r t a k i n g into account , however , the i n f luence of the x - inc l ina t ion and the l a t i t ude d i s to r t ion in t he AT, t h e r e w a s n o t h i n g l e f t bu t an i r r e g u l a r l ine wh ich shows negl ig ib le e r ro r s . I t is doub t fu l w h e t h e r i t h a s a n y sense to e x p r e s s p ro jec t ion e r r o r s in t h i s case in t he f o r m of a rad ia l d i s tor t ion . T he in f luence o f l ack of i n t e r sec t i on o f g imb le ax is etc. will no t show up in a c i r cu l a r f o r m a r o u n d the n a d i r l ine, a l t h o u g h t he f l ex ion of space rods of a s y s t e m of m e c h a n i c a l p ro jec t ion m a y be t he cause of th i s t y p e o f de fo rma t ion . Fu r the r~ more I do no t bel ieve t h a t i t is j u s t i f i e d to s u b t r a c t t he i n f luence o f x - inc l ina t ion and l a t i tude d i s to r t ion in an A7 f r o m t he d e f o r m a t i o n s in the penci l of r ays . The me thod ind ica ted by Lycken for t he d e t e r m i n a t i o n of t h e s e e r r o r s is excel lent . I t will be n e c e s s a r y , however , to inc lude the i n f l uence of t he r e s idua l e r r o r s o f t he a d j u s t m e n t of x - inc l ina t ion and l a t i t ude d i s to r t ion in the f ina l d i a g r a m of e r ro r s in a g r id m e a s u r e m e n t a s u s u a l in n o r m a l prac t ice .

The s t u d y of H o t h m e r abou t e r r o r s in g i mba l ax i s is v e r y u s e f u l because it g ives a n u m e r i c a l i m p r e s s i o n abou t t he i n f luence of t h e e r ro r s in one of the m o s t v i ta l e l emen t s of all p h o t o g r a m m e t r i c r e s t i t u t i o n mach i ne s . H i s d i a g r a m s can help to f ind a d i agnos i s in the eva lu t ion of r e s u l t s of g r i d m e a s u r e m e n t s . I a g r e e fu l ly wi th h i s w a r n i n g t h a t a n o r m a l u s e r of an i n s t r u m e n t should no t s t a r t w i t h co r r ec t i ons of g imba l axis .

The t h i r d p a r t of t he pub l i ca t i ons in t h i s sec t ion dea l s w i th t he p rob l ems of re la t ive and abso lu t e o r i en ta t ion . T h e y a r e m a i n l y Swedish , all based on t he f u n d a m e n t a l work of H a l l e r t wh ich wa s d e m o n s t r a t e d in a g r e a t n u m b e r of pub l ica t ions , a p a r t of wh ich however was a l r e a d y k n o w n f r o m pub l i ca t ions in v a r i o u s per iodica ls in the pas t . Neve r - the less p a r t 4 of Vol. XI I g ives a v e r y good rev iew abou t t h i s i m p o r t a n t Swedi sh work.

One of t he r e so lu t ions o f Comm. II, accepted by t h e Genera l A s s e m b l y w a s abou t the r eques t to f ac to r i e s and a u t h o r s to accep t a s t a n d a r d i z e d coord ina te sys t em. The approva l of t h i s p roposa l is of p rac t i ca l va l ue and we will exp la in t he consequences in a special sho r t a r t ic le in t h i s review.

9

5. Comm. III. Aerial triangulation and its application to geodesy.

If we s tar t here with radial t r iangulation we meet f i rs t a new Wild Radial Triangu- lator according to the design of Roelofs. In this publication Roelofs studies the systematic errors i n scale- and azimuth t ransfer , using as a measure of comparison the s tandard accidental errors of aerial tr iangulation in space. It is proved tha t the former are generally much smaller than the latter, apar t f rom a few exceptional cases of topography. The drawback naturally is, tha t it gives only two coordinates. In f lat or almost f lat terrain, ilowever, the third coordinate will never have sufficient precision if we use aerial survey in an economic way. Therefore in all those cases radial tr iangulation can be excellent for the determination of the planimetric control. The appearance of this precision radial t r iangnlator again laid stress on the necessity to develop fur ther means for the determination of the nadir point either by horizon cameras of special design or by means of the soiar periscope.

Fagerholm from Sweden continued his effor ts to increase the precision of the slotted templet 'method. In the Swedish exhibit prototypes were shown for fas t and accurate point t ransfer and for templet slottingi Not only in Sweden but also in Austr ia effor ts are made for the design Of a stereoscopic ins t rument for the t r ans fe r Of points f rom one photograph to the otiaer. These instruments must replace the classical, now over 20 year s old Dutch method to t r ans fe r such points by the use of floatifig marks which are moved by free,hand. Several Dutch investigations have shown tha t this can be executed with a mean square error of 0.02--0.03 ram. According to the experience we obtained with the device for stereoscopic t ransfer in the radial, . tr iangulator of 1935 built by de Koningh, it is doubtful whether this precision can be increased considerably [5]. All movable mechA- nical par ts are sources Of errors which very easily surpass a few hundredths of a millimeter.

Regarding the adjustment of aerial t r iangulation again a number Of p'ublications, dealing with the compensation of single str ips according to the method of least squares, were presented. I have the impression that fur ther development along this line, a f ter what is known so far, has not much sense. A long single str ip has a very weak structure. The improvement of it b y - m e a n s of a perfect method of compensation does not change the principle of this structure. Moreover i t is questionable whether there i s a good proportion between this improvement and the ,cost in time and money of such a C0mpen- sation: We believe therefore tha t with aerial t r iangulation the same wilt happen as with the t raverse in groilnd survey: in almost all' c~ases we are satisfied with an approximate method'of adjustment. The method published by the French IGN at the 1952 Washington Congress is a very sat isfactory parallel with the computation of~ a normal traverse. There is f i r s t an adjustment of the elements of orientation by linear distribution of the closing errors. Based on these adjusted elements of orientation the closing errors in coordinates are computed and then these errors are distributed along the str ip by means of a second- order binomium. Another well-known example is the graphical method of Zarcicky, Van tier Weele tried successfully to simplify the least square method of adjustmen t by deriving the coefficients of the third-order binomium of the correction equation f rom the seven closing errors of a s tr ip which equation was based on the publication of Roelofs~ of 1952 in this review.

We have the impression, however, tha t a least square method for the adjustment of a s tr ip limits its practical value to the derivation of the correction formula$ as carried out by Roelofs and of the mean square errors in the compentated coordinates. The various publications show tha t they all come to the same result but along di f ferent lines: a third-order correction curve. I personnaly like the method of Vermeir which, in part icular for long strips, gives a very rapid solution for the principal points. Corrections for points outside the centre line of the strip can be found by interpolation. This may be an approximation: we believe, however, tha t this method which in this way takes only a very short time will give sat isfactory results [6].

10

I f we rea l ly wish to app l y the me t hod of l ea s t s q u a r e s we m u s t no t cons ider t he s t r i p b u t each ind iv idua l p h o t o g r a p h w i t h i t s s u r r o u n d i n g ove r l aps and e x p r e s s t he condi t ions fo r each of t he c o m m o n poin ts , bo th in the s a m e s t r ip and in t he a d j a c e n t s t r ips . W e know, however , t h a t t h i s m e t h o d r e s u l t s in such a n u m b e r of condi t ion equa t ions , t h a t t he solut ion of th i s sys t em, even w i t h electronic c o m p u t i n g m a c h i n e s , is v e r y d i f f icul t .

We believe t h a t V a n der Weele in t h i s congres s m a d e a con t r i bu t ion to a v e r y p r ac t i - cal and , also f r o m t he theo re t i ca l po in t o f view, sound solut ion. H e f o r m s blocks o f a l imi ted n u m b e r of p h o t o g r a p h s , for i n s t a n c e 3 s t r i p s of 7 p h o t o g r a p h s each, or 4 s t r i p s wi th 9 p h o t o g r a p h s , d e p e n d i n g on t he r e q u i r e m e n t of precis ion. These sho r t s t r i p s a r e connec ted w i th each o the r by l i nea r t r a n s f o r m a t i o n . The i n t e r n a l e r r o r s o f each o f t he se l i t t le blocks can be neg lec ted and t h e a v e r a g e of t he two v a l u e s of t he coord ina te s o f common po in t s a re used ins ide each smal l block. V a n der Weele p roposes to m a k e t e m p l e t s for each of t he se blocks accord ing to t he m e t h o d of t he s t e r e o t e m p l e t s proposed by some A m e r i c a n au tho r s . A s lo t ted t e m p l e t l ay -ou t of t he se blocks will p rovide u s w i th a mechan i ca l a d j u s t m e n t of t h e whole block. I f t he "errors c aused by t he u se of t he m e c h a - nical m e a n s fo r t he s lo t ted t emp l e t l ay -ou t a r e no t accep tab le i t is possible to app ly a l eas t s q u a r e block a d j u s t m e n t on a se t of such blocks. The in t roduc t ion o f such blocks m e a n s t h e n t h a t we g r e a t l y l imi t t he n u m b e r of condi t ion equa t i ons and t h a t the l eas t s q u a r e a d j u s t m e n t m e t h o d comes p e r h a p s w i t h i n t he r a n g e of p rac t i ca l possibi l i t ies . W e believe t h a t in addi t ion to t he e x i s t i n g m e t h o d s fo r block a d j u s t m e n t such as t h a t o f Zeller, i t will be des i rab le to c a r r y ou t f u r t h e r e r p e r i m e n t s w i th block a d j u s t m e n t s a l ong these l ines.

A r e m a r k a b l e m e t h o d fo r a d j u s t m e n t of h e i g h t s w a s o f f e red to t he cong re s s by t h e F r e n c h IGN. I t is a pa ra l l e l of t he s lo t ted t e m p l e t m e t h o d s fo r he igh t s , viz. a m e c h a n i c a l solut ion. We h a v e t he i mpre s s i on , however , t h a t t he execu t ion of th i s m e c h a n i c a l compen- s a t i on is less s imple t h a n t he s lo t ted t e m p l e t fo r p l a n i m e t r y .

R e g a r d i n g the m e a n s to d e t e r m i n e some of t he e l emen t s Of abso lu te o r i en t a t i on o f e ach exposure we have to m e n t i o n f i r s t a C a n a d i a n pub l i ca t ion in t he C o n g r e s s ~um]0er of " P h o t o g r a m m e t r i a " wh i ch g ives a desc r ip t ion of t he methQd of P a l m e r wh ich t r i e s to keep t he f lex ion in a z i m u t h o f each s t r i p u n d e r control . A t each 5 th e x p o s u r e o f a ve r t i ca l p h o t o g r a p h he t a k e s a low obliclue of t he hor izon on i n f r a r e d f i lm. On t h i s hor izon photo= g r a p h a s t r a i g h t l ine is iden t i f i ed by m e a n s o f a point , close to t he hor izon a n d a n o t h e r po in t close to t h e n a d i r of t he p h o t o g r a p h . T h i s l ine is t r a n s f e r r e d to t h e n e x t low oblique p h o t o g r a p h a n d to all ve r t i ca l p h o t o g r a p h s a n d keeps t he y -va lue in each s t r i p u n d e r control . The r e m a r k a b l e a c c u r a c y ob ta ined in a s t r i p of 120 km, wh ich gave a m a x i m u m e r r o r in y -d i rec t ion o f 7.9 m and of 15.3 m in a n o t h e r s t r ip o f 250 km, is an ind ica t ion o f t h e g r e a t va lue of th i s me thod .

T h i s pub l i ca t ion b r i n g s u s a g a i n to t he g r e a t i m p o r t a n c e of hor izon p h o t o g r a p h y . We ind ica ted th i s a l r e a d y in s eve ra l p laces in t h i s c o n g r e s s r e p o r t and we h a v e to m e n t i o n in th i s r e spec t in p a r t i c u l a r t he r e s u l t s ob ta ined by t he F i n n i s h M i l i t a r y Topog~-aphic Service a s g iven in t he N a t i o n a l R e p o r t of F i n l a n d a n d as will be exp la ined in a special a r t ic le by Lt. Col. L S f s t r S m in t h i s review. P h o t o g r a p h y ob ta ined w i th old p r e w a r Ze i ss P-10 Topogon c a m e r a s in t he scale o f 1 : 40,000 in s t r i p s of a l e n g t h o f 20 k m wi th fu l l control on bo th ends were t r i a n g u l a t e d in a p r e w a r S t e r e o p l a n i g r a p h . The a v e r a g e m e a n ~ q u a r e e r r o r in h e i g h t w a s be tween 2.0 a n d 2.5 m a n d in x- and y=coordina tes be tween 3 and 4 m. Th i s is w i t h o u t a n y doubt a r e m a r k a b l e r e s u l t wh ich is due to t he u se of t he hor izon c a m e r a which , in t h i s case, enab led i t s u s e r to d e t e r m i n e the e l emen t s of o r i en t a - t i on w i th a m e a n s q u a r e e r r o r of abt . 3 c en t e s i ma l m i n u t e s , w h i c h is a b o u t 1 : 2,000.

T h e r e w a s n o t v e r y m u c h n e w s a b o u t t he d i rec t d e t e r m i n a t i o n o f t he coo rd ina t e s o f :the exposu re s t a t i on by e lect ronic m e a n s . Dr. Za rc i cky exp la ined a g a i n in a v e r y good p a p e r t he a p p l i c a t i o n o f S h o r a n to e s t ab l i sh ho r i zon ta l cont ro l f o r p h o t o g r a m m e t r i c m a p p i n g in inaccess ib le a r eas . AS f a r a s r e s u l t s a r e m e n t i o n e d he g ives a m e a n s q u a r e e r r o r of abt: 20 m in the pos i t ion of a n a d i r po in t in a f l i g h t l ine; abou t h a l f t h i s v a l u e

11

if a certain point in the terra in is tied in between two trig. stations. Regarding theoretical block adjustments a remarkable article of the Belgium profes-

sor Baetsl~ "Compensation des blocs photogramm~triques en altim~trie par relaxation" must be mentioned.

A very important pa r t of the activities of Comm. III was devoted to two closely related experiments. The f i rs t was tha t regarding the "essai contrSl~" (controled experiment) No. 1 organized by the International Society of Photogrammetry as a consequence of a resolution of the 1952 congress. Although this resolution originally expressed something of a spiri t of competition of methods and instruments, the meeting of Comm. II, III and IV in 1954 in Gunten, Switserland, changed this character into tha t of a controled experiment. The French IGN has made a grea t ef for t to make these experiments a success. The f i rs t dealth with aerial t r iangulation over a Swiss ter r i tory "Hutwil" (50 X 50 km). Photographs were taken with an automatic plate camera Poivilliers SOM ~ f

125 ram. The area was covered with 7 str ips of abt. 15-18 photographs each. At the edges and in the middle were cross s t r ips . Scale of photography 1 : 50,000. So f a r only results of the French IGN have been published. These results however, are of a remarkable high quality. The method of tr iangulation was that published by the IGN at the 1952 Congress. Computation was carried out in different ways, with and without the use of the cross strips, with complete numerical t reatment , with mechanical compensation with stereotemplets for planimetry and with the mechanical adjustment of heights according to Masson d'Autume.

The most remarkable results were obtained by the method which uses none of the cross str ips and full control at the ends of all filling strips with one isolated point in the middle of three str ips and as additional height control one series of points in the middle of all filling strips. The mean square errors in planimetry are m~ ~ 2.83 m, m x = 2.95 m and m z = 3.72 m. The method with cross str ips gives for these values 3.31 m, 2.89 m and 3.43 m. After the mechanical compensation of heights this last figure was reduced to 2.56 m. In this case the only ground control consisted of three pairs with full control at the ends and in the middle of each cross strip. These r e s u l t s w e r e obtained from photographs on glass plates without the use of any auxiliary instrument. All observations were carried out in the Stereotopograph type B. applying the Porro Koppe system with the use of the original negatives. This result proves that on 2500 sq.km with only 9 pairs with full ground control results can be obtained which are entirely sufficient for a 1:20,000 topographic map. This shows what can be reached with a system of photography and restitution which is organized as one complete chain, in which all links have the same strength. I t is not in part icular the quality of instruments or operators, but the result of a perfect organization taking good care of all details of the complete procedure. We believe tha t this consideration is not always taken into account.

The second experimental t r iangulat ion which was introduced to the congress was that of the European Organization for Experimental Photogrammetric Research (OEE- PE) . This European organization published in "Photogrammetr ia" a special report regarding its activities. The Congress was informed about programme and progress of this organization. There were, however, still no results available. They will be published in a future number of Photogrammetr ia af ter a thorough study of the f i rs t computations by the scientific committee, dealing with aerial tr iangulation in this organization. Its value has been explained sufficiently in this review and therefore it is not necessary to repeat that the advantage of its activity is tha t we, for the f i r s t time in the history of photogrammetry, will obtain a great quanti ty of f igures and results based on material and observations which can really be compared. Perhaps it is also for the f i rs t time that not only the good results, but a l l results, good and bad, will be discussed and later on published.

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6. Comm. IV. Application of Photogrammetry and aerial photography for surveying the earth's surface.

In the meetings of Comm. IV the results were presented obtained by applying photo~ grammetry to the production of maps. The task of this commission was distributed over three subcommissions: the f i rs t dealt with the application to cadastral surveys, reporter Dr. H[irry from Switzerland, the second with the application to the survey of urban areas, reporter Dr. Dubuisson from France and the third with the production of topographic maps, reporter Prof. Dr. Bachmann._

The f i rs t subcommission obtained important results from various institutes which took par t in the comparative mapping of the testfield Oberriet in Switserland with groundcontrol points of very high precision which was made available by the Swiss Federal Cadastral Service with the assistance of the Wild Factory. The same material consisting of photographs in di f ferent scales on film and plates were used by Comm. C of the OEEPE. The repor t on the work, until that moment achieved by Comm. C was presented by Prof. G. Lehmann from Hannover. This report, however, did not contain more than the programme of work, the regulations for the execution without indication of the results in time and precision.

Much more important was the report of Dr. Hfirry who published results obtained by four different inst i tutes: the Photogrammetric Inst i tute in Jerusalem, Rikets Alm~nna Kartverk Stockholm, Kungl. Landm~iteristyrelsen, Stockholm and the National Photo- grammetric Research Inst i tute in Ottawa. Fur thermore Prof. Hallert f rom the Royal Technical Universi ty in Stockholm has carried out with the same material certain experiments to solve special problems. The value of this test field lies par t ly in the very high precision of the ground control points which have a mean square error in position of 0.5 cm and in height of 0.47 cm. For the determination of the accuracy of photogrammetric restitution such a high precision of the test points is necessary.

One important result mentioned by Dr. H~irry is that the identification of boundaries between parcels which are not indicated by stones, shows errors between 10 and 15 cm. These differences are larger than in accordance with the precision of photogrammetric plotting. This is a result which confirms my own experience already published over 20 years ago. I t means tha t the full capacity of photogrammetric plotting in cadastral surveys can only be achieved in cases in which the boundaries are marked by stones and signalized. In all other cases the precision of our instruments will not be used to its utmost.

Important are also the comparisons with di f ferent sizes of signals. Regarding this problem we mention the experiments carried out in Austr ia by Hlawaty and Stickler with signals of different size, different colours on different background. Comparison of the result of the Oberriet area as mentioned in Dr. H~irry's report with the Austr ian result shows tha t it is highly worthwhile to continue these Austr ian experiments.

Regarding the computation of the results, Dr. H~irry mentions that all part icipat ing centres have computed the coordinates of all signalized points by means of a linear t ransformation. Dr. Hfirry is for cadastral photogrammetry, in which the relative precision is of still more importance than the absolute precision of the position of points, in favour of the application of an aff ine t ransformation, dividing the surface area of each pair into triangles. The advantage in th is case will be that the residual errors in the control points will be zero and tha t disagreeable discrepancies between adjacent pairs are prac- tically avoided.

Regarding precision, Dr. Hfirry computed, independently from the part icipat ing centres, the mean square er ror in planimetry and height for each pair. This was possible because the number of test points in each pair was sufficient viz. between 19 and 231. A study of his statistics however shows tha t it is ra ther dangerous to draw conclusions from his figures. The mean square er ror in coordinates m R is reduced to the value m c in the plane of the negative. He f inds values between 9 and 21 ~. Dr. H~rry computed

~3

fur thermore the mean square er ror m d in distances of points between 2 and 30 m and found as an average for m a = 0.496 X m~. This proves t ha t the accuracy of the relat ive position of points is much h igher than in the coordinates. This is of the u tmos t importance for the application of pho tog rammet ry to cadas t ra l surveys.

A fu r t h e r conclusion which is not too dangerous, is t ha t the mean square er ror m c

decreases with the scale. Dr. Hi i r ry gives for the scale 1 : 6,000 m c = 15 .~ which value decreases regular ly to 11 ~t for the scale 1 : 21,500.

Another resul t is t h a t about the precision of the determinat ion of heights. For the resti tution of Avio tar photographs in f i rs t -order machines, Dr. H~irry found 0.120/00 of z for fi lm and 0.1150/0 o for plates, with res t i tu t ion in f i rs t -order machines. For the Aviogon 10 cm these f igures are in f i rs t -order machines 0.165O/o o and in second-order in s t rumen t s

0.196°/00 of ~. Dr. H~irry f in ishes h is report with a few suggest ions which should be taken into

account when cont inuing the experiment . One of these is t ha t for the comparison of film and plates it will be necessary to use two di f ferent cameras unde r the same circumstances , which in our opinion means t h a t we m u s t use them s imul taneously in the same plane.

A fu r the r remark of Dr. H~irry is t ha t increase in accuracy can be expected f rom the use of convergent photography with 100% overlap in each pair. Both Dr. H~irry and the author of th is article have been in favour of the use of this sys tem for m a n y years. We believe t h a t the more favourable base-height rat io and the la rger scale of photography which is possible with the same number of pa i r s because of the g rea te r overlap, are all considerations which s t reng then the tendency towards the use of convergent photography for cadast ra l large-scale work.

This point h a s been discussed in d i f fe rent ways. Brucklacher presented his paper in Comm. I describing the new Zeiss Twin camera which replaced the pre-war camera of Zeiss used in Switzerland by Bosshard t and in the Nether lands by KLM and the Delft services.

The convergent photography was discussed in still another way in a paper by George D. Whitmore: "Economic factors in the in tegra ted photogrammetr ic sys tem of the US Geological Survey." He ment ions the economic advan tages of the use of wide-angle low oblique photography, ei ther t r ansverse or convergent. The point of discussion regard ing the use of wide-angle for convergent photography as was usual in Europe before the war with s tandard angle, is, whether t h e very large base he igh t ratio of 1.23 instead of 0.63 with vertical wide-angle will not dis turb the stereoscopic image. It seems tha t the US Geological Survey has no diff icul ty in this respect, because in a discussion about the role which can be played by a super wide-angle Whi tmore even says: " a practicable u l t ra- wide-angle camera would provide the means of exploiting the convergent photography technique fu r the r , to obtain still la rger model coverage". This ma y be t rue in a t r ans - verse position of such a twin camera. We do not believe, however, t ha t th is method can be applied to convergent photography, resu l t ing in a" base he ight ratio which would be still la rger than the 1.23 with the normal wide-angle. Such type of photography would give too m a n y so-called dead spots of which no stereoscopic image can exist because objects are only visible f rom one exposure station. We have personal experience with the Muen- chen p an o ram a camera which in i ts stereoscopic image with normal overlap, has about t h e same base height ratio. Such a mul t i tens vertical camera however can be used with a much larger overlap without d is turb ing the economy of the system. This, however, is not possible with the convergent photography which requires exposure in such a way t ha t we have full overlap of each photograph. I t would be of importance to f ind out wha t is the compromise between the economic considez'ations for reduction of the number of overlaps and the qual i ty of the stereoscopic image. It is obvious t ha t this will be d i f fe rent for different scales and for d i f fe rent types of terrain .

A very in teres t ing publication is the "Rappor t sur l 'essai contr61~ No. 2 Verco~s. Etabl issement photogramm~tr iques d 'une carte h l'~chelle 1 : 50.000". This report present-

2

14

ed by t he P r e s i d e n t and by S e c r e t a r y of Comm. II (P rof . B a c h m a n n a n d Ing. H~ber l in ) i n f o r m s u s abou t t he r e s u l t s of t he p roduc t ion of a r e g u l a r t o p o g r a p h i c m a p in the scale 1 : 50,000 of an a r e a in F r a n c e o f abt . 170 sq.km. E a c h p a r t i c i p a t i n g service w a s al lowed to u se i ts own special m e t h o d s a n d t h e F r e n c h I G N h a s t a k e n p h o t o g r a p h s as r equ i r ed

by the p a r t i c i p a t i n g services . T h e r e f o r e t he F r e n c h I G N h a s used p h o t o g r a p h s in t he scale 1 : 50,000 wi th SOM f i l m c a m e r a a n d an SOM wide -ang i e p la te c amera . The Swiss h a v e used Wi ld RC 7 p h o t o g r a p h s in the scale 1 : 80,000 and the I t a l i a n E I R A p h o t o g r a p h s f r o m 4000 m h e i g h t t a k e n w i t h t h e Gal i l eo-Santon i Tr ip le c a m e r a o f which t h e two oblique c a m e r a s h a v e an inc l ina t ion o f 45 ° . R e s t i t u t i o n w a s c a r r i e d ou t by t he F r e n c h in t h e Poivi l l ie rs Type B a n d a second r e s t i t u t i o n in t h e Poiv i l l ie rs t y p e D. The Be lg ian M i l i t a r y Topog raph i c Service used t he s a m e p h o t o g r a p h s a s t he F r e n c h I G N and ca r r i ed ou t t he r e s t i t u t i o n also in the Poiv i l l i e r s t y p e B. T he Swiss r e s t i t u t i o n w a s done in t h e Wi ld A7 a n d the Wi ld A8 b u t on ly fo r One pa i r ; t h e I t a l i a n r e s t i t u t i o n in t he Galileo San ton i S t e r e o c a r t e g r a f o IV. T he r e p o r t c o n t a i n s fu l l de ta i l s abou t t ime and prec is ion b u t we will ind ica te on ly t he m o s t i m p o r t a n t f i g u r e s . T he m e a n s q u a r e e r r o r of h e i g h t s der ived f r o m c o n t o u r s in t e r r a i n s w i t h s lopes of over 5% is F r a n c e t ype B 2.3 m, and in t ype D 2.4 m ; fo r B e l g i u m 3.0 m ; ' f o r S w i t z e r l a n d in t h e A8 1.5 m a n d fo r t h e I t a l i a n r e s t i - t u t i o n 2.7 m. The m e a n s q u a r e e r r o r a f t h e obse rva t ion in h e i g h t of i sola ted po in t s in t he s a m e success ion : 1.1 m a n d 2.2 m ; 1.7 m (in t he AT) and 1.7 m. A v e r y pecu l i a r c o n s t a n t e r r o r w a s found in t he B e l g i an a n d S wi s s r e s t i t u t i o n by t a k i n g t h e a v e r a g e of all e r r o r s in he igh t . T h e s e f i g u r e s a r e + 0 . 2 m a n d +0 .5 m fo r F r a n c e , - - 2 . 0 m fo r Be lg ium, + 0 . 7 m fo r I t a l y a n d + 1 . 4 m for S w i t z e r l a n d in t he AT. The r e p o r t e r s did no t f ind a n y ex- p l a n a t i o n fo r t h i s cons ide rab le s y s t e m a t i c e r r o r in t he d e t e r m i n a t i o n o f he igh t s .

The on ly po in t o f objec t ion a g a i n s t t h i s v e r y va luab le r epor t , f o r wh ich we a r e v e r y g r a t e f u l , l ies in i t s conclus ion. W e bel ieve t h a t t h e s t a t e m e n t t h a t t he prec is ion o f t he con tou r l i n e s i s i n d e p e n d e n t o f the u se o f e i t he r 1s t o r 2nd o rde r i n s t r u m e n t s and of t he scale o f p h o t o g r a p h y w i t h i n t he l imi t s of t h i s e x p e r i m e n t is no t jus t i f i ed . I t will be n e c e s s a r y to collect m u c h m o r e m a t e r i a l be fo re such a conclus ion wil l be acceptable . R e g a r d i n g t h e u s e of 2nd o rde r i n s t r u m e n t s t h i s c an on ly be based on t h e r e s u l t of t he r e s t i t u t i o n o f t he Swiss p h o t o g r a p h s 1 : 80,000 in t he A8 wh ich is c a r r i ed ou t only for one pa i r . Be tween t he Po iv i l l i e r s t y p e D a n d B t h e r e is a cons iderab le d i f fe rence , in paL-- t i c u l a r in t h e m e a s u r e m e n t o f i sola ted points . A l t h o u g h it is in accordance w i th m y own expdr ience t h a t t h e prec i s ion of m e a s u r e m e n t of h e i g h t in t he Wi ld A8 is a b o u t the s a m e a s in t he Wi ld A7, we do n o t bel ieve t h a t i t i s j u s t i f i e d to g ive such a s t a t e m e n t in such g e n e r a l t e r m s , a s done by P ro f . B a c h m a n n .

W e d r a w the a t t e n t i o n to t he special pub l i ca t ion of E I R A wh ich g ives a fu l l descr ip- t ion of i t s p a r t i c i p a t i o n in t he cont ro led t e s t Vercors . No. 2.

Our r e p o r t abou t t h i s i n t e r e s t i n g t e s t would n o t be comple te i f we did no t men t i on t h e n u m b e r o f de t a i l s wh ich shou ld be r e p r e s e n t e d on a r e g u l a r t opog raph i c m a p a n d wh ich were no t shown in t h e p roduced m a n u s c r i p t s . W e h a v e to real ize, however , t h a t t h i s r e s t i t u t i o n is ca r r i ed o u t w i t h o u t a n y r e c o n n a i s s a n c e in advance . B a c h m a n n s t a t e s t h a t 55% of t he objec ts wh i ch a r e e x a m i n e d in t he f ield, a r e r e p r e s e n t e d ve ry correc t ly , 13% is m i s s i n g , a n o t h e r 13% wh i ch is indica ted , should no t be r e p r e s e n t e d a n d fo r a n o t h e r 19% d i f f e r e n t t y p e s of e r r o r s in the iden t i f i ca t ion a r e made .

W e now come to the second s u b c o m m i s s i o n of Comm. IV, wh ich dea ls wi th s u r v e y s of u r b a n a reas . R e p o r t e r Dr. B. L. Y. Dubu i s son . T h i s is in f a c t the s a m e t y p e o f l a rge- scale work as ca r r i ed ou t fo r c a d a s t r a l pu rposes , a l t h o u g h s o m e t i m e s wi th lower requi- r e m e n t s for precis ion. T he m o s t i m p o r t a n t p a r t of th i s r epo r t is t he d i scuss ion be tween two F r e n c h in s t i t u t e s , each a p p l y i n g t he i r own special sys t em. The f i r s t is t h e service of Dr . D u b u i s s o n of t h e M i n i s t r y o f R e c o n s t r u c t i o n and H o u s i n g and t he second of t he F r e n c h IC-N. Dr. D u b u i s s o n appl ied t he r e c t i f y i n g method . He t h e r e f o r e used a c a m e r a wi th a p r inc ipa l d i s t ance of 50 cm, f i l m 30 X 30 cm, wh ich is p rovided w i th t h r e e gy ro - scopes in o rde r to ob ta in s u c h d a t a fo r rec t i f i ca t ion , t h a t he needs in t he t e r r a i n only a

15

distance for scaling. For plott ing it is necessary to use an i n s t rume n t like his rest i tut ion pantograph in order to el iminate the displacement caused by dif ferences in height . The advantage of this method is the possibility to decentralize the construct ion of his maps in the various surveyors offices and to make use of pr ivate surveyors. The IGN of France has carried out a photogrammetr ic survey of a cer tain a r e a apply ing thei r normal method us ing the Stereotopograph Poivilliers Type B. This work ha s been reported in a special publication. Dr. Dubuisson s ta tes in his conclusion t ha t the use of f i rs t -order photogrammetric equipment reduces the importance of field work wi thout increasing the quanti ty of office work. He believes however, t ha t his rest i tut ion method with its very small f inancial inves tment is more suitable for the use by small su rvey ing organization. We believe th is to be a general problem in pho togrammet ry which even comes back in the article of Mr. Whitmore, mentioned above, as he opposes the general use of wha t he calls "the heavy i n s t rumen t s " for normal plott ing work. In th is respect the French IGN with its grea t quant i ty of f i rs t -order i n s t rumens takes pe rhaps an exceptional position.

7. Comm. V. Non-topographic applications of photogrammetry.

This commission which has been en t rus ted to I ta ly with Prof. Giovanni Boaga as president has dis t inguished in its repor t between the following subjects:

a. archi tecture and general technique 2 b. archeology and fine a r t s 1 c. na tu ra l sciences 9 d. mi l i ta ry applicat ions 4 e. medicine and anthropology 9 f. cr iminal applicat ions 0 g. other applicat ions 3

The last column indicates the number of papers presented to the Congress. The two papers mentioned under g. of Mr. Lemaire and Hubeny are both of a general character , discussing the possibilities of micro-s tereophotogrammetry.

The paper of Mr. Lemaire deals with the precision in a l t imet ry and p lan imet ry and the paper of Mr. Hubeny gives the l imitation of the possibilities of this method. We believe these papers are worth while to read for all those who s t a r t u s ing th i s method for the solution of var ious problems.

Also another Belgian publication is h ighly in teres t ing: Cat te la in and Vermeir make propaganda for the old idea to set up an in ternat ional photo archive of all f amous buildings and sculptures of the civilized world.

As was to be expected much work is done in the field of electronic microscopy. FrQf. Burkhard t built a special i n s t rumen t for this work.

The s i tuat ion in th is Comm. V is expressed in a r a t he r critical way in point 2 of its resolutions:

one will f ind no new method of fundamen ta l importance in the received papers : some new in s t rumen t s for mak ing photographs and for special purposes are made. There is no news in the realization of special res t i tu t ion i n s t r u m e n t s . . . .

The au thor of the resolutions does not need any comment f rom our side, bu t we strongly suppor t a f u r t he r pa r t of his resolution:

it would be good if every nat ional society fo rms a special section of wihch everybody interested in these m a t t e r s will be a member.

That means t h a t the kind of specialization in accordance with the chapters mentioned above will be desirable. On the other hand I believe tha t only by a systemat ic cooperation between pho togrammet r i s t s and var ious specialists of for instance medicine etc. Comm. V can become a really impor tan t commission of the ISP.

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8. Comm. VI. Education, Terminology and Bibliography.

This commission is entrusted to Austria, President Prof. Neumaier, Secretary Prof. Barvir. The most important subjects of this commission are the polyglot dictionary and the project of the bibliography. The Austr ian Society of Phot0grammetry presented to the congress proof copies of its dictionary of which the text in English, French, German, Italian, Spanish, Swedish and Polish is now available. The dictionary will have for each language a special volume of about 100 pages. The contents of each volume is abt. 5000 words in alphabetical order in the language* concerned. Behind each word are columns for the 6 other languages with the numbers under which the translat ion in each of these languages in the other volumes can be found. One blank column makes it possible to add another language. The price of this very useful piece of work, for which the photogrammetric world is most grateful to the Austr ian Society and to those gentlemen in the various countries who have assisted Austr ia in the translations, is ra ther low, viz. 2 US dollars for each volume 1).

As far as the bibliography is concerned it may be mentioned tha t the proposal made by Comm. VI to entrust this par t to the Inter. Training Centre in Delft was accepted. The author of this article however mentioned tha t he only could take the responsibility for this publication if the cooperation of several of the national societies can be obtained. He promised to send a circular letter to the national societies before the end of this year mentioning the financial consequences of this enterprise with some more details about the necessary cooperation.

With respect to terminology no special decisions were taken. I have the impression however that it would be of great advantage if at least for the main photogrammetric symbols a certain standardisation could "be obtained. We would welcome any effor t of the new council to prepare proposals which could be accepted at the next International Congress. A small committee might be appointed for the preparation of proposals regarding definitions and standardization of symbols of the main features of photogrammetry.

Regarding t ra ining there is not much news. In the report is mentioned that most of the t ra in ing in photogrammetry is combined either with engineering courses like in the English speaking world, or with the study for geodetic engineer like in several European countries. The only insti tute specialized in the use and application of air photographs to map production and in the interpretat ion for geological and agricultural purpose is still the Delft International Training Cent?e. Several universities find tha t the purchase of sufficient equipment is ra ther expensive and fur thermore tha t the time necessary for a real practical t ra in ing cannot be made available in most of the courses with which the study of photogrammetry is combined.

9. Comm. VII. Photographic interpretation. This commission was entrusted to the American Society of Photogrammetry which

appointed Charles G. Coleman as its President an4 Earl J. Rogers as reporter. This commission, established at the proposal of the US before the Washington Congress, had found in the American Society such an excellent representation that this commission in Stockholm has again been entrusted to the USA. The report which was also published in Photogrammetric Engineering, shows the material in four major sections: General, Natural Resources Application, Engineering Application and Military Application.

Under par. "General" attention is paid to the photographic interpretat ion techniques, the equipment, personnel and training.

Amongst the instruments various devices are mentioned for the determination of slopes in stereoscopic images. In par t icular the US Geological Survey has been active in

1) Please order this dictionary before the end of this year at the adress of Prof. Barvir, Techn. Univ. Graz, Austria.

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this respect and we draw attention to the stereo-slope comparator of Hackman, the so- called Super-Duper-Dipper. Two papers were delivered about the t ra in ing of geologists in the USA. They deal, however, more with the t ra in ing in elementary photogrammetry for geologists than with the real t ra in ing of geological interpretat ion of photographs.

In accordance with the grea t activity in the field of photo-interpretat ion in that country he American Society has expressed the desire to publish a Manual of Photo- Interpretation. We all would welcome such a useful textbook. We hope, however, that an editorial board will be constituted which will review the contents of the book in order to avoid a certain lack of equilibrium in the t rea tment of various subjects and the kind of duplications which exist in the American Manual of Photogrammetry. A fur ther wish regarding this important publication would be that the editors receive such international cooperation tha t a real international textbook published by the American Society is the result. I am fully aware however that this depends mainly on the willingness of experts from abroad to answer in a positive sense the request for help from all those interested in photo-interpretation as mentioned in the report of Comm. VII on page 10.

Regarding the interpretat ion techniques I have the impression tha t colour photography is mentioned more frequently in this report than in 1952. Even for geology colour photographs were taken from the air and used with some success for locating lightly looking mineral deposits. Also in forest ry colour photography is used more and more, in particular for the determination of damage by insects, diseases etc.

Another feature is that notwithstanding the improved quality of photographic images, there is still a tendency to use ra ther large-scale photographs. Even in geology for which type of work the oil geologists use always photographs in the scales 1:40,000--1:50,000 vertical photography of abt. 1 : 20,000 and sometimes of even larger scale are nowadays used for detailed analysis of special outcrops. This example shows tha t the method of the early days of aerial survey to use for interpretat ion the same photographs made for instance for topographic mapping loses ground. Together with the recognition of the possibilities of photo-interpretat ion for d i f ferent purposes and of its grea t economic value comes the tendency to take special photographs for each special purpose. The cost of photography may be ra ther high, but the advantage of photography in a scale adapted to the special kind of in terpreta t ion required, will pay in many cases. An example of this tendency is also the geologic mapping carried out by the US Geological Survey from high altitude photography in the scale 1 : 60,000 by means of a Kelsh Type plotter. This method combines the coverage of large areas in one stereomodel, 5 X enlargement of the original scale of photography and perfect plotting of the geological map. I cannot yet see in how f a r the combination of this high altitude flying with a 6 inch lens could be improved for interpretat ion purposes by the combination with t ransverse oblique photography with two 12 inch cameras covering the same strip of the wide-angle camera. This type of photography would give a scale which is twice as large, the base length would be half. The advantage would be the la rger size of certain details. The study under a normal stereoscope of these obliques in combination with Kelsh plotting of the small-scale verticals could perhaps give a very good solution for geological interpretat ion and geological mapping.

In the fores t ry section there is a remarkable paper presented by Hans Axelson regarding the effect of photo-scale on the use of aerial photographs in Swedish forestry. His conclusion, drawn from a great number of test fields and di f ferent interpretors is, that the photography in a scale 1 : 33,000 is not appreciabl:y inferior to 1 : 16,000 for measurements of tree heights and estimations of various Stand factors when enlarged pictures at 1:15,000 are utilized. This conclusion is a contradiction of the American methods as indicated on several places in li t terature. We are inclined, however, to accept this Swedish s ta tement in part icular for density estimations. Whether it is true for measurement and in part icular for identification of specimen, is an entirely different problem. Axelson recommends for Sweden scales not smaller than 1 : 30,000 of photo-

2 "

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graphs which should enlarged to 1:20,000. I have the impression that jus t like the author says i t is not wise to conclude too much f rom his work concerning ±he practicaI photo-scale in forestry. I t would be highly interest ing however, to carry out research work about this important economic problem. Anotker question is the difference between the use of enlarged original photographs and the observation o f pr in ts with stereoscopes with s t rong magnification, such as made by Wild now with an 8 X magnification.

This commission did not present very much about soil survey. The report does not mention many applications of this method and only one paper by Dr. J. S. Veenenbos of the Delft ITC was presented. I believe, however, tha t the ITC-Buringh method, developed in Delft during recent years, is gaining ground rapidly. I t is applied nowadays already in several countries, in par t icular in the Middle Eeast and in Africa. I consider this as one of the most important contributions of the Delft insti tute to the economic use of air photographs.

10. Decision of the Congress.

Various delegate meetings and two meetings Of the General Assembly were held. We will mention only the most important decisions. The f i rs t is tha t the Brock Award (see "Photogrammetr ia" Vol. XII, page 3 9 ) w a s granted to Dr. Bertele of the Wild firm. His successive creations of the Aviotar, Aviogon and his latest. Super Aviogon have improved the quality of the raw material of the photogrammetr is ts and interpre= tors to such an extent tha t we really can speak of "an outstanding and proven contribution to photograrmnetry". These optical tools put into the hands of all of us and the stimulance which these lenses are for other optical designers, fully jus t i fy the grant ing of this f i r s t Brock Award to Dr. Bertele. I t does not change anything of the merits of Dr. BelC~ele however to say tha t Dr. Richter, the creator of the Topogen lens, which is the mother of all wide-angle lenses made a f te r 1934 also has been considered b y the Council of the ISP as a very serious candidate for the Brock Award. His death hn February 1956 required a reconsideration of the problem by the Council of the ISP which without any hesitation came to the nomination of Dr. Bertele.

While dealing with awards we must mention a few honorary memberships. A few members received this honour for various reasons. Dr. Hiirry as the promotor of the use of photogrammetry in large-scale precise mapping and the application to cadastral sur')ey; General Huraul t as the promotor of the use of photogrammetry in small- and medium scale topographic mapping ancl as the promotor of what we call the French photogrammetric system; Prof. Dr. Cassinis as the man who is responsible for several theoretical and experimental studies which have fur thered photogrammetry in Italy and as organizer, founder and president of the Ital ian photogrammetrie group; Mogenaen as the past President of the ISP and responsible for the organization of the ISP and its congress during the past four years. I like to mention specially the honorary membership granted to Prof. Dr. Bauersfeld, the creator of the Zeiss Stereoplanigraph and of many elements of designs o f photogrammetric instruments. Although never taking an active part in discussions in the international photogrammetric world and standing in the background, it was fully justif ied tha t the ISP honoured this ingenuous designer and scientist in this way because of the grea t influence he has had not only on the development of photogrammetry in Germany, but also f a r outside that country.

The most important decision was the acceptance of the invitation of the British Society of Photogrammetry to hold the nex t congress (in 1960) in London. The second offer was from Belgium, which it kindly withdrew in favour of England which already in 1952 invited the congress in case Sweden would not have been in a position to receive the ISP. The British Society announced the nomination of Maj. General R. L. Brown as President of the new Board. Col. R. T. L. Rogers, Director of the Fairey Air Survey Ltd., as secretary-general and Mr. J. E. Odle, Director of Williamson Manufactur ing Co. Ltd., as t reasurer . We believe that everybody can congratulate the International Society

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with this new executive beard. The General Assembly decided to nominate the members Janicot, Reading and Schermerhorn for another four years. The Swedish Society appointed Mr. Fagerholm as new member of the council represent ing the outgoing executive board.

There was fu r ther a discussion about the distribution of the various commissions. The result is as follows:

Comm. I France III Italy V Germany VII USA II Belgium IV Switzerland VI Austr ia

More important than this was the discussion in the delegate meetings regarding the organization of the next Congress and the acceptance of the proposals concerned by the General Assembly. The new president, General Brown had several informal talks with the members of the council and with others. This resulted a f t e r w a r d s in a s tatement made during the delegates meeting. His main aim is to avoid the difficulties experienced at the present congress as described in the f i rs t pa ragraphs of this article. The president's proposal is

1. publication of a limited number of invited papers on special subjects; 2. discussions init iated by a panel of invited persons, one of whom should be the

author of the paper ; 3. the marshalling, categorizing and f i l ter ing of the multitude of other papers which

are presented to the congress. Around the summer of 1958 the national societies and the technical committees will

be requested in a circular let ter to indicate to the council which are the subjects which in their opinion should be thoroughly discussed at the 1960 congress. The answers will be considered by the boards of the technical committees and by the council. In the beginning of 195.9 one of more authors will be requested to prepare a paper about each accepted subject" These articles must be received before the end of 1959 in order to make it possible to publish the complete collection in a special number of "Photogrammetr ia" which will be simultaneous a par t of the new volume XIII of the International Archives. This publication must be distributed at least four months before the congress to all those who have announced their intention to participate. Cost of this par t of the Archives will be included in the total costs of Vol. :~III.

Regarding the publication of the national reports and of the comittee reports no special decisions were taken.

In addition to these II, III and IV par t s of Vol. XIII of the Archives there is still the possibility to include in pa r t V those papers presented to the congress by various authors and accepted by the Committee Boards. These papers can only be included in the Archives if the author for his own account supplies sufficient reprints.

It would be highly desirable to take such measures r.egarding the committee reports that they form together p a r t III of the Archives and could be published simultaneously with part IV containing the invited papers. As these commission reports are sometimes published in national reviews it is not very likely tha t it will be possible to obtain repr ints of these reports already five or six months before the congress.

I have the impression tha t with an organization as outlined here considerable improvement in the efficiency of the congress could be obtained. I believe however, tha t the organization is in the able hands of our British colleagues who have sufficient experience with this kind of work as they showed for instance in 1955 at the British Common- wealth Survey Officers Congress in Cambridge which I had the honour to attend.

The next. congress will again be di f ferent f rom its predecessor. I t will be still more difficult because of a larger number of part ic ipants and a larger scientific contribution. Notwithstanding the succes achieved in Stockholm, we all are aware tha t the Inter- national Society of Photogrammetry cannot stand still. We must develop our congresses step by step. The outlines given by General Brown are without any doubt a contribution

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to this future development. One of the most i m p o r t a n t items necessary for this development, however, is the cooperation of all photogrammetrists . This cooperation can be given by accepting the invitation for prepar ing papers and above all, by sending the material, ~/hatever it may be, within the time limits. It is again this delay which has given our Swedish colleagues the disappointment not to be able to a t ta in the aims put forward in 1952. Let us hope tha t our Brit ish colleagues will have a bet ter cooperation from all of u s than we have given our Swedish colleagues.

Technical Resolutions

adopted by the General Assembly at the VII I Inte~national

Congress for Photograznmetry in Stockholm Juli 26th 1956.

Commission I (E). ] !

1. Commission I recommends that the Washington d ra f t s tandard on test methods be amended to take into account the comments received before and during the Congress. A revised draf t should be submitted by the Commission Board to the various National Societies for comment and published in Photogrammetria .

2. Commission I considers tha t closer cooperation between established camera test ing laboratories is desirable. Exchange of information on the techniques of testing camera and exchange of air cameras are recommended.

3. In order to ensure continuity of work between Congresses and to meet Maj. General Brown's suggestions, Commission I desires tha t the National Reporters to the Com- mission be appointed as soon as possible, be individuals whose at tendance at the next Congress is probable and be experienced in the work of the Commission, as defined by resolution 2.

4. Commission I expresses the wish tha t for the future, the time-table be so arranged as to allow the members of the Congress to visit more thoroughly the exhibition and to allow the exhibitors' s taf fs to at tend a pa r t of the Congress sessions without increasing the exhibitors' burdens.

5. Commission I expresses the wish that , because of good results obtained so far, tests on registrat ion of the horizon be extended to some other countries.

Commission I (F).

1. La Commission I recommande que le projet de norme de Washington sur les m~thodes d'essai soit modifi~ pour tenir compte des suggestions revues avant et pendant le Congr~s. Un projet r~vis~ sera soumis par le Bureau de la Commission aux diverses Soci~t~s Nationales pour avis avant d 'etre publi~ dans Photogrammetria.

2. La Commission I estime qu'il est tr~s d~sirable d'~tablir une collaboration plus 4troite entre laboratoires de eontrole bien equip4s. Elle recommande les 4changes de documents sur les techniques de controle raises en oeuvre et les ~changes de chambres de prise de rues a4riennes.

3. Afin d 'assurer la continuit4 du tra:~ail entre les Congr~s et d 'aller au devant des suggestions du Major G~n~ral Brown, la Commission I d~sire que les rappor teurs natio- naux ~ la Commission soient design,s d~s que possible, soient des personalit~s qui assisteront probablement au prochain Congr~s et qui connaissent bien les techniques concernant le travail que la Commission se propose de promouvoir, tel qu'il est d~fini dans la r~solution No. 2.

4. La Commission I exprime le d~sir qu'~ l 'avenir, l 'emploi du temps soit conqu de telle mani~re que les Congressistes puissent visiter plus compl~tement l 'exposition et que le personnel appar tenant aux f irmes exposantes puisse assister partiellement aux

21

sessions du Congr~s , s a n s qu ' i l en r~sul te u n a c c r o i s s e m e n t des c h a r g e s suppo r tde s par les exposan ts .

5. La Commission I ~met le voeu que, en r a i son des r ~ s u l t a t s e n c o u r a g e a n t s d~jh ob tenus les essais d ' e n r e g i s t r e m e n t de l 'hor izon soient ~ t endus ~ d ' a u t r e s pays .

I ommission II (F ) . I

1. Consid~rant le g r a n d in t~re t que p r~sen te l ' essa i contrSl~ No. 2 , ,Vercors" p o u r l '~ta- b l issement de ca r t e s t o p o g r a p h i q u e s ~ l '~chelle de 1 : 50.000, la C o m m i s s i o n II p ropose : a. que les i n s t i t u t s a y a n t par t ic ip~ ~ l ' essa i pub l i en t i n t ~ g r a l e m e n t les r ~ s u l t a t s et

les document s qu ' i l s on t ob tenus a ins i que l 'expos~ des md thodes et proc~d~s ut i l is~s b. que l 'ex4cut ion de n o u v e a u x essa i s soit env i sag~e c. que la direct ion de c h a q u e essa i de lev~ soi t a s s u m ~ e p a r u n e seule commiss ion d. que des v a r i a n t e s so ien t env i sag~es d a n s l ' ex~cut ion des e s sa i s con{rS14s pour fac i -

l i ter l '~tude de probl~mes i m p o r t a n t s t o u c h a n t a u doma ine i n s t r u m e n t a l . 2. L'activit4 de la C ommi s s i on II doit 8t re l imit~e ~ l '~ tude des a p p a r e i l s et des m~thodes

de res t i tu t ion. 3. E t an t donn4 le rSle i m p o r t a n t que j o u e n t les g r a n d e s m a c h i n e s ~ ca lculer en g~od~sie

e t en pho tog ramm~t r i e , il es t r e c o m m a n d ~ que la Commis s ion I I S'OCcupe des ques t i ons s 'y r a p p o r t a n t pou r a u t a n t qu 'e l les t o u c h e n t d i r e c t e m e n t a u x a p p a r e i l s et m4 thodes de res t i tu t ion.

4. Vu les solut ions nouvel les de r e s t i t u t i o n qu 'on p e u t encore e n v i s a g e r d a n s le doma ine ~lectronique et le doma i ne p u r e m e n t num~r i que , il e s t . souha i t ab t e que de nouve] les recherches dans ce doma i ne soient en t r ep r i s e .

5. Vu les n o m b r e u s e s d i f f i cu l t~s que p r~sen te l ' app l ica t ion des m~thodes de raise en place num~riques e t m~cano-op t iques en t e r r a i n s t r~s a c c i d e n t , s, i l e s t d~sirable que des dtudes th~or iques et p r a t i q u e s so ien t e n t r e p r i s e s d a n s ce domaine .

6. Vu les d i f f icu l t~s caus~es p a r le choix p lus ou mo ins a r b i t r a i r e du sens pos i t i f des ~l~ments d 'o r i en ta t ion d a n s les a p p a r e i l s de r e s t i t u t i o n e x i s t a n t s , l ' a s sembl~e g~n4ra le recommande : a. ~ u x c o n s t r u c t e u ~ s d ' i n s t r u m e n t s de chois i r pou r les c o n s t r u c t i o n s f u t u r e s un

syst~me de coordonn~es d~fini p a r un t r i~dre direct , son o r ig ine se t r o u v a n t au centre de p ro jec t ion e t la v a l e u r de Z i n d i q u a n t la d i s t ance de la p ro jec t ion

b. a u x a u t e u r s de chois i r le s igne des f o ~ n u l e s en adcord a~ec ce sys t~me de pro jec- tion et ceci i n d ~ p e n d a m m e n t des a p p a r e i l s de r e s t i t u t i o n qui son t ~. leur d ispos i t ion

c. aux ~coles de n ' u t i l i s e r pou r l ' e n s e i g n e m e n t que des f o r m u l e s bas~es s u r l ' in t ro- duction du s y s t ~me de coordonn~es propose.

7. Vu l ' int~r~t que pr~sen~ent les ~ tudes e x p ~ r i m e n t a l e s pou r le p rogr~s des me thodes et des i n s t r u m e n t s , la C ommi s s i on II r e c o m m a n d e que les t r a v a u x e x p ~ i m e n t a u x en t re - pris pa r I ' O E E P E se d~veloppent d a n s le cad re d ' m m col labora t ion avec la SIP.

[ CommissionIII (F). [ 1. Revenant su r la r~solu t ion no. 1 adopt~e au Congr~s de W a s h i n g t o n , t a Commis s ion

recommande q u ' a v a n t le p rocha in Congr~s , u n colloque au mo ins rdun i s se les sp~cialistes de l ' a (~rot r iangula t ion. Le p res iden t de la Commiss ion , ap r~s avo i r recuei l l i t o u s l e s av i s qu' i l j u g e u t i l es f ixera le lieu et la date , l ' o rdre du j o u r et la l i s te des pe r sonnes invit~es.

2. En r u e d ' a u g m e n t e r le r e n d e m e n t des s~ances de t r a v a i l la C o m m i s s i o n r e c o m m a n d e que la R~solut ion g~n~ra le no. 10 soit appl iqude, p a r t i c u l i ~ r e m e n t en ce qui concerne : a. la s~lection des c o m m u n i c a t i o n s i m p o r t a n t e s b. la publ icat ion "et la d i f fu s ion a v a n t le Congr~s

22

c. le t ra i t ement de ces communications, individuellement ou par groupes, par discussion pr~par~e, dirig~e et sans prdsentat ion orale.

3. La Commission recommande que les essais control ,s d 'a~rotr iangulat ion soient pour- suivis pendant la p~riode 1956-1960 et que le president en f ixe le r~glement en s ' a idant de l 'exp~rience acquise et apr~s consultat ion des pr inc ipaux intdress~s. D~s ~ pr6sent, la Commission constate qu'il est gdn~ralement souhait~: a. que le caract~re pra t ique donn~ ~ l 'essai no. 1 soit ma in tenu dans les essais ul t&

r ieurs

b. que toute lat i tude soit, comme pr~c~demment laiss~e aux par t ic ipants dans le choix des m~thodes et des moyens d'exdcution

c. que l 'obligation de t ravai l ler sur polygone ~ t ranger soit supprimde d. que cet assoupl i ssement du r~glement air comme contre-partie un renforcement de

la discipline d'ex~cution eL des possibilit~s de contrSle. Dans ce but, que la com- municat ion des documents de t ravai l au directeur de l 'essai soit fr~quente et r~gu- li~re

e. que chaque par t ic ipant fournisse au directeur de l 'essai un rappor t d~taill~ sur les t r av au x effectu~s.

4. La Commission constate avec sat isfact ion qu 'une bonne collaboration c 'est ~tablie entre I 'OEEPE et la SIP dans le domaine de l 'a~rotriangulation. Elle recommande que, dans cet espri t de collaboration, les ~tudes exp~rimentales ent repr ises soient act ivement poursuivies et ~tendues.

5. Le Commission recommande qu 'un groupe de t rava i l soit constitu~ pour l 'application la photogramm~tr ie de la s ta t is t ique math~mat ique et de la th~orie des er reurs . Les

membres de ce groupe seront d~sign~s par le Conseil. Le groupe sera consid~ra comme une section de la Commission III au 9~me Congr~s. I1 a u r a la facult~ de fa i re aux au t res commissions ou groupes de t ravai l de la Soci~t~ In ternat ionale des recomman- dations concernant les essais in ternat ionaux.

Commission III (E).

1. Refe r r ing to resolution no. 1, adopted a t the Congress of Washington , the Commission recommends t ha t before the nex t Congress, at leas t one meet ing of specialists in aerial t r i angula t ion will be organized. The Pres ident of the Commission, a f te r hav ing collected all opinions which he th inks useful , f ixes place and t ime; agenda and l is t of invited persons.

2. With the purpose to increase to efficiency of the Congress meetings, the Commission i°ecommends t ha t General Resolution 10 be supported, par t icular ly in respect of a. the selection of impor tan t papers b. the publication and distribution before the Congress c. the papers t rea ted individually or in g~'oups, by means of prepared discussions

without oral presentat ion.

3. The Commission recommends t ha t the controlled tes ts in the field of aerial t r iangulation are continued du r ing the period 1956-1960 and tha t the Pres ident f ixes the rules, t ak ing into account the obtained experience a f t e r consultat ion of the most concerned par t ic ipants . At this moment , the Commission es t imates t ha t it is desirable: a. t ha t the practical character , given to tes t no. 1, be main ta ined in f u r t h e r tes ts b. tha t every liberty will be left, as has been done formerly, to the par t ic ipants for

the choice of methods and means of execution c. t h a t the obligation to work on foreign tes t f ields be cancelled d. t h a t th is modification ha s on the other hand as a consequence t ha t the rules for

the execution and control of the work will be more strict. For this purpose the com- municat ions of working documents to the Director of the tes t s should be f requent and regu la r

23

e. t h a t each par t ic ipant provides the Director of the tests with detailed report about the work t h a t has been executed.

4. The Commission s ta tes with sat isfact ion tha t a good cooperation has been established between the O E E P E and the ISP in the field of aerial t r iangulat ion. She recommends that, in this sense of collaboration the exper imental s tudies will be actively continued and extended.

5. There shall be a working group on the application of Stat is t ical Science and Theory of errors to Pho togrammet ry . This group shall be appointed by the Council and shall be considered a section of Comm. III a t the 1960 Congress. It will be authorized to make recommendat ions concerning internat ional exper iments to other commissions or working groups of the ISP.

i Commission IV (F). [

1. La Commission IV cont inuera les t r avaux exp~r imentaux et essais contrSl~s en collaboration avec les organisa t ions int~ress~es.

2. Le Pres ident de la Commission IV nommera aussi tSt que possible, les Pres idents des sous-Commissions IV-l , IV-2 et IV-3.

3. Les Pres idents des sous-Commissions prendront contact avec les par t ic ipants aussi t6t que possible pour ~tablir un p rog ramme provisoire des t r a v a u x exp6r imentaux et essais contrbl6s qui sera discut~ entre eux ~ une r~union sp~ciale tenue en Europe et en Am~rique.

4. Les rappor ts sur les t r avaux exp6r imentaux doivent 6tre termin6s et soumis par les part icipants: une ann6e avan t le prochain Congr~s: de cette faqon la derni~re a nn i e sera consacr6e ~ l ' ana lyse des r~sultats.

.5. Une conference g6n6rale de la Commission IV sera organis6e au moment opportun entre les deux Congr~s.

Recommendations No. 1 . ?

Il es t recommand~ que chacun des par t i c ipan ts ~ l 'essai contr61~ no. 2 ,,Vercors" (s'il ne l 'a pas d~j~ fai t ) adresse au Pres ident de la Commission IV-3 un rappor t d~taill~ eomprenant :

la mSthode utilis~e et le mode d'ex~cution des t r a v a u x les temps passes aux diverses operat ions les plus impor tantes les r~sul ta ts obtenus et, s'il y a lieu, des commentai res sur ces r~sul ta ts une reproduction de la minute du lev~.

Ces rappor t s sera ient adress~s ~ toutes les d~l~gations des pays a dhe ra n t ~ la SIP apr~s avoir ~t~ reproduits int~gTalement. Les conclusions d 'ensemble devraient porter sur tous les t ravaux , quelle qu'en soit l'o~rigine, et une fus ion serai t souhaitabie entre les deux rappor ts pr~sent~s au Congr~s sur l 'essai no. 2.

Recommendations No. 2.

I1 est recommand~ que la Commission IV-3 comprenne les lcv4s aux ~chelles plus petites que le 1 :50 .900 dans des experiences aux peti tes ~chelles.

Commission I V (E) .

1. Commission IV will continue exper imental work and ,,essais contrSl~s" in cooperation with interested organizat ions.

2. The Pres idents of Commissions IV will name as soon as possible the Pres idents of subcommissions IV-l , IV-2 and IV-3.

3. The Pres idents of subcommissions will contact the par t ic ipants as soon as possible to

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establish a tentat ive program for experimental work and ,,essais control ,s" which will be discussed between them at special meetings held in Europe and America.

4. Reports on experimental work must be completed and submitted by part icipants one year before the next Congress so tha t the last year may be devoted to analysis of results.

5. An interim general meeting of Commission IV should be organized at a convenient time.

Recon~mendat ions I.

1. It is recommended tha t each part ic ipant of the "essais control6s" no. 2 "Vercors", (if not already done) submit to the President of Commission IV-3 detailed reports including : a. method and manner of execution b. time distribution for major par ts of the work c. results, with comments, if any d. reproduction of the manuscript .

2. Copies of this report should be distributed to each member country of the ISP. A general report should refer to all submissions, regardless of their origin, and it would be desirable to have a general report of all experimental work, both European and non-European.

Recoqn,mendation H.

It is recommended tha t Commission IV-3 includes mapping scales smaller than 1 : 50.000 in its program.

I ommission V (F).

1. Le nombre des m~moires pr6sent6s au VIII~me Congr~s de la SIP d~montre que, depuis 1953, l ' int6ret port6 aux applications sp6clules de la photogramm6trie a aug- ment6 dans plusieurs secteurs de la science et de la technique. I1 faut n6anmoins observer que les rapports envoy6s h la Pr6sidence pal' les Soci~t6s Nationales int6ress6es n 'ont pas toujours ~t6, ni tr~s complete, ni tr~s originaux. Le caract~re de recherche isol6s des ~tudes et des applications sp~ciales de la photo- g r a m m 6 t r i e - plut6t que d'application reguli~re et g6n~ralis6s de ces proc6d6s - - a 6t6 maintenu pendant tes quatre ann6es qui se sont 6ccul6es depuis le congr~s de Washington. Quoique les applications non-topographiques de la photogramm~trie soient d6j~ tr~s nombreuses et tr~s importantes, le nombre r6duit de sp6cialistes et d ' instruments et les difficult~s rencontr6es pour faire entendre aux non initi6s les avantages qu'on peut t i rer de la Photogramm6trie, sont encore les raisons principales de la modeste diffusion de ces m6thodes dans tous les Pays, m~me les plus ~volu6s. Nous ferons noter cependant la pr6diction de Mr. McNeil, qui croit que les applications non-tepographiques de la photogramm6trie devraient souclasser clans un avenir rapproch~ les applications cartographiques.

2. On ne remarque aucune m6thode nouvelle d' importance fondamentale dans les communications recues: quelques nouveaux appareils pour la prise de vues et pour des buts sp6ciaux aient 6t6 r6alis6s, il n'y a pas de nouveaut6 dans la r6alisation d'appareils sp6ciaux de resti tution; de m~me il n 'y a pas encore de classification syst6- matique d6taill6e des applications sp6ciales de la photogramm6trie et il faudrai t que pendant les quatres prochaines ann6es, cette classification des applications sp6ciales de la photogramm6trie et il faudrai t que pendant les quatres prochaines ann~es, cette classification des applications d6jh employees soit envisag6e.

25

3. Il faut favoriser au maximum les recherches et les exp4riences darts ]e domaine tr~s ~tendu des applications sp4ciales: sans doute les applications topographiques de la photogramm~trie ont - - elles absorb4 jusqu'~ present la plus grande par t ie des efforts; mais aujourd' hui on peut dire que la photogramm~trie topographique est assez d4veloppde pour ne plus exiger le concours de t o u s l e s photogramm~tres. On pourra donc consacrer clans l 'avenir un peu plus de temps, d'~tudes et d'exp~riences aux m4thodes et aux appareils destines ~ la photogramm~trie non-topographique. Nous prions les Soci~t~s Nationales de bien vouloir inviter leurs membres ~ orienter une partie de leurs effor ts dans cette voie. On recommande de recueillir la Iitt4rature existante e t celle que sera prochainement publi~e et on propose d'~tablir un concours international pour un texte de photogramm~trie non-topographique, qui soit en m6me temps th~orique et pratique clair et aussi complet que possible sur les connaissances actuelles dans ce domaine.

4. On souhaite que l 'enseignement de la photogramm~trie non-topographique soit intro- duit dans les ~coles sup~rieures, pour les matri~res o5 ses applications peuvent con- tribuer au progr&s scientifique et technique (g~ologie, science du sol, g4nie civil, mddicine, m~t4orologie, science foresti~re, etc.).

5. Les recherches et les expdriences dans le domaine des applications sp4ciales de la photogramm~trie devraient trouver l 'appui des Soci~t4s Nationales et des industries sp~cialis~es, surtout en vue de la formation d'archives de prises de vues des chef d'oeuvres d'architecture et des recherches prdsentant un int~ret scientifique ou artis- tique, comme la photogramm4trie radiographique, l'~tude de l ' infiniment grand (astronomie) et de l ' infiniment peti t (molecules), les mesures des vagues et des nuages des glaciers, des fluids en mouvement etc.

6. On dolt constater que pendant les quatre ann~es qui viennent de s'~couter, les travaux effectu~s r4v~lent un manque de coordination, m~me entre les sp4cialistes d'un m~me pays. Souvent m6me, ils ne t iennent pas compte des connaissances d~j~ acquises. I1 serait donc souhaitable de former dans chacque Soci4t~ Nationale une section sp~ciale qui r4unirait routes les personnes qui s ' int~ressent ~ ces questions. Des contacts p~riodiques permet t ra ient de fa i re mieux connaltre les possibilit~s et les avantages de la photogramm~trie. On peut conclure que les applications non-topographiques de la photogrammdtrie sont en constant p r o ~ s et en t i rer la certitude qu'elles s 'entendront et s 'a f f i rmeront toujours d'avantage.

I Commission VI (E). I 1. Since the polyglot dictionary is ready to be published, the Austr ian Society of Photo-

grammetry is requested to s tar t distribution on the conditions mentioned in the subscription pamphlet.

2. The Board of Commission VI is requested to charge the Intel~national Trainin~ Centre for Aerial Survey (I.T.C.) at Delft with the establishing of a bibliography of photogrammetry in cooperation with the national societies. The bibliography will be organised in accordance with the rules set forward by the new Board of Com- mission VI. The publication of each title and resum4e will be either in English, French or German.

3. Commission VI of the International Society of Photogrammetry shall encourage and assist schools and universities offer ing photogrammetric education to increase the proportion of basic sciencies, mathematics and electronic engineering in their curic- cula so that photogrammetris ts of the future may be better equipped to develop new methods for increasing the speed and accuracy of mapping procedure&

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Commission Vll (E). I The work of Commission VII dur ing the pas t repor t ing period has been conceraed

with assessing the rapid advances made by photographic in terpre ta t ion in i ts many fields of application.

The growth of this science has reached a stage where the present commission report- ing mechanism, and the four-year repor t ing period are inadequate to main ta in cognizance of the field. The resolutions proposed, therefore, a t th i s time, are designed to improve the ~ervice rendered by Commission VII as an agency for the in te rna t ional exchange of information on photographic in terpre ta t ion.

Resolved: t h a t a repor t summarying the activit ies in photographic in te rpre ta t ion on an in ternat ional level be prepared annual ly by Commission VII, and published by the nat ional society of the country responsible for the commission.

Resolved: t h a t working-groups be set up under Commission VII to ma in ta in cognizance of and repor t upon for example the following fields of application of photographic in terpreta t ion.

Photography (avai labi l i ty of photo coverage, desirable photo specifications etc~). Photographic In te rp re ta t ion Equipment and Techniques. In te rpre ta t ion of surface configurat ion, drainage, soils, geology structures. In te rpre ta t ion of vegetation. In te rpre ta t ion of urban, ru ra l and industr ia l s tructures. In te rpre ta t ion of ice. Archeology and equivalent applications.

Resolved: t h a t nat ional societies be advised of the increased interes t in photographic in terpreta t ion, and t h a t they ass is t the work of Commission VI I by designat ing "working group reporters" , and by providing technical and bibliographic informat ion on; photographic in te rpre ta t ion for the annua l reports.

Re]erences :

[1] W. Schevmerharn, Impressions of the 1952 Washing ton Congress of the In terna t ional Society of Photogrammet~, Photogrammetr ia , 1952-53, page 1-11.

[2] H . L . Oswal, Flexure of photographic plates under the i r own weight and some modes of support and consequent photogrammetr ie errors, Photogrammetr ic Record, Vol. 2, Nr. 8, page 130-144.

[3] W. Schermerhorn and K. Neumaiev, Systematische Fehler bei der Aerotr iangulat ion, Photogrammetr ia , 1939, p. 160.

[4] E . H . Thompson, Thompson Wat t s p lot t ing machine, The Photogrammetr ic Record, 1954, Vol. I, No. 3.

W. Scherme~horn, Das Thompson Wat t s Stereokart ierger~t , Photogrammetr ia , 1953- 54, Nr. 4.

[5] W. Schermerho~n, Die Luftbi ldmessung in den Niederlanden und Niederl. Ost-Indien yon 1934 bis 1938, Intern . Archiv. f Photogrammetr ie , Vol. VIII .

[6] P . A . Vermeir, La t r iangula t ion a~rienne, Bulletin de la Soci~t~ Belge de Photo- gramm~trie , Nr. 35, Mars 1954, l~ages 17-57.

impressions of the 1956 stockholm congress of the international society of photogrammetry

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