FIG. 1. General Layout of the Tactical Image Interpretation Facility AN/TSQ-43. TIIF.

CARL ORLANDO

U. S. Army Electronics CommandFort Monmouth, N. J. 07703

Tactical Image Interpretation Facility

A van contains a measuring viewer encodeddirectly into a computer.

(Abstract on page 96)

D URING WORLD WAR II and the KoreanWar, image interpretation was accom­

plished by photographic interpreters (PI) us­ing simple-stereoviewers, drafting compassand rulers in locales not necessarily assignedor in tended specifically for photographic inter­pretation. The photographic interpreter oftenperformed his task under adverse operatingcondi tions and, in many instances, under atent with poor lighting facilities. This simpletechnique resulted in slow interpretation ofimagery and a low confidence factor for ac­curate in terpretation.

Since the Korean War, and with the adventof the more sophisticated surveillance sensors,such as Side Looking Radar (SLAR), MovingTarget Indicator (MTI), and infrared, cou­pled with the advanced design of aerial photo­graphic systems, and the necessity for con-

92

tinuous surveillance, the inadequacy of thePhoto Interpretation Kit with its simple toolshas been demonstrated. The PI, or whatshould now be called the Image Interpreter,is required by his commander to extractinformation from these sensors in the shortestpossible time, in order that timely and ade­quate countermeasures may be taken to coun­teract the enemy. The Army has increased itsinterpretation capabilities with the develop­ment of the Tactical Image InterpretationFacility (TIIF) AN/TSQ-43.

THE T ACTlCAL IMAGE In terpretation Fa­cility, is a self-contained equipment mountedin an expansible van for extracting in telli­gence information from photographic, radar,and infrared imagery. A number of viewersare employed for magnifying the imagery

TACTICAL IMAGE INTERPRETATION FACILITY

FrG. 2. Interior of TJIF. The light table is shown on the left and thestereo viewer to the right of the photograph.

93

under investigation. The resul ts and observa­tions are transmitted to the requesting com­mander by using telephone and teletypewriterequipment included in the TIIF.

The imagery (paper positives and trans­parencies) may originate from Army, Navy,Air Force, and other agencies. This imageryis received in rolls of film or paper, and in cutsheets. The different formats which can beaccommodated are: 2i by 21 inches, 4! by 4!inches, 9 by 9 inches, and 9 by 18 inches; and70 mm., 5-inch, and 9-inch panoramic stripsphotography. Radar and infrared imageryproduced on strip of 70 mm., 5-inch, and 9!­inch film can also be interpreted in this fa­cility.

The TIIF, is employed at Division, Corpsand Field Army. One or more of these unitsmay be employed depending on the workloadof the echelon. Operationally the equipmentis located as closely as possible to the informa­tion gathering sensors, airfield and drone sites,and to the photographic processing vans. TheTIIF provides 24-hour image interpretationservice to the commander. In normal operat­ing workloads, five image interpreters arehoused in the TIIF. Under very heavy work­loads, as many as ten image interpreters canbe accommodated.

FIGURE 1 SHOWS the general layout of theInterpretation equipment and the majorcomponents which include the cabinet spaceand viewer-computer. The illustration shows

the van expanded to allow work space aroundthe interpretation equipment. Two LightTables are located, one on each side of theVan. Figure 2 shows, to the left of the photo­graph, one of these devices. This equipmentis primarily used for the preliminary scanningof imagery for obtaining intelligence informa­tion for use in initial or so called Hot-report­ing. However, it can also be used for detailstudy of the imagery for reporting more com­plete information. I t is provided with a glasstop surface 11 inches wide by 40 inches longand illuminated with a cold cathode light

CARL ORLANDO

94 PHOTOGRAMMETRIC ENGI EERING

FIG. 3. Plotting tables. One in position, to the left, and the other collapsed, to the right of the photograph.The communication booth is shown in the center.

source which provides continuously varyingillumination over a 20 to 1 ratio. Illuminationof 1,200 foot-Iamberts is possible. Suitablemasks are provided to eliminate glare of thesurface not covered by the film being ex­amined. A vacuum hold down maintains thefilm area flat. A microscope carriage is pro­vided to hold a microscope and stereoscopefor observing the imagery.

The imagery may be in roll form up to 500feet capacity, 70 mm. to 9t inches wide, andcu t sheets to cover the en tire area of the ligh ttable. As part of the light tables there areprovided two stereoscopes for use with 5-inchand 70 mm. stereo photography. These in­struments, by interchanging proper lenses,can also be used to view imagery of all sizesin two dimensions. Optical power pods aresupplied having a continuous magnificationratio of 0.7 to 3X. With proper selection ofobjective lens and eyepiece, magnification upto 120X can be accomplished.

'rHE STEREOSCOPIC VIEWER, shown to theextreme right of Fig. 2, accommodates stereoviewing for film widths of 5 inches and 9tinches, up to 1,000 feet in length. The directviewing optics (not visible in this illustration)are designed for continuous variable magnifi­cation from 2.5X to 25X. The platen is pro­vided with vacuum-hold-down device forflattening the photography under examina­tion. A continuously variable light source isprovided similar to that used in the lighttable.

Two plotting tables are provided in the for-

ward portion of the van, left portion of Figure3, to allow the image interpreter to viewimagery and make photographic mosaic oroverlay. The surface is provided with a varia­ble light source similar to the other equip­ments, and is used for viewing transparencies.An overhead light permits examining opaqueprints. The tables are designed to be raisedout of the way to allow the van to be closedduring transport as shown in the extremeright of Fig. 3.

A VIEWER COMPUTER is included, (Figure 4),and is mounted in the rear of the van forviewing imagery and obtaining ground mea­surements. The viewer portion consists of twolight tables and means for holding films from70 mm. to 9t inches wide up to 500 footspools. A micJ"Oscope is provided for observ­ing target details and for aiding in positioninga measuring cursor. The cursor consists of aprojected light, which can be positioned inany point on the image by means of a "joy­stick" control.

A computer forms part of this equipment.This is a Field Data Digital Army computer,M-18(FADAC), adapted for this applicationby proper programming. The computer re­ceives its inpu t from X - Y encoders activatedby the cursor movement. The mechanicalaccuracy is obtained by means of X and Ylead screws which maintain the movementof the cursor within the stringent require­ments. The encoder, which transforms theanalog movement of the lead screw to digitalinputs to the computer, is set for bit informa-

TACTICAL IMAGE INTERPRETATION FACILITY

FIG. 4. Viewer-computer. Note computer Matrix to the right of photograph.

9S

tion of 12 microns. The computer is in turnprogrammed to compute this input into a 32­bit word for a total memory 8,192 words. Thiscapability produces a mensuration instru­ment which can measure down to 25 microns.I n the full length of the Y direction of 18inches, it is possible to measure within anerror of 1 part in 5,000.

The computer is programmed for rectifyingthe image under observation and obtainingground distances; heights of objects, using thedisplacement technique and stereopair meth­ods; ground areas; and distances of windingroads. Further, it can determine distances ofobjects located in more than one frame, dis­tances of two points located at different alti­tudes, and determine map coordinates of tar­gets under observations in either geographicor universal transverse mercatory system,(UTM). Rectification of oblique and panor­amic photography can be accomplished aswell as that of infrared and radar imagery.The output readout is in the form of nixietube numerical presentation and hard copyteletypewriter. The computation is doneautomatically after the operator has pro­grammed the computer with the known vari­ables applicable to his problem.

Mensuration compu tations are achieved bythe operator of the viewer computer by in­serting the proper parameters in the com­puter. These parameters include, focal lengthof lens, altitude of the aircraft, attitude of thecamera (obliquely), type of sensor under ex­amination, e.g., photo, infrared or radar, andthe special parameters associated with them.These factors are programmed in to the com­pu ter by pressing the appropriate bu ttonsidentifying the known variable. The computeris then set for operation and an automaticreadou t of the desired information is ob-

tained. For instance, if the ground distancebetween two points is desired after insertingthe proper parameters in the computer, theoperator first moves the cursor to one poin tand turns an Initial Set knob. He then movesthe cursor to the second point and turns the"Compute knob". The computer automatic­ally displays on nixie tubes or teletypewriterreadou t the distance covered on the ground.The computer compensates for oblique aswell as fOf" panoramic distortion of photo­graphic imagery, and known distortions ofinfrared and radar imagery.

OTHER EQUIPMENT provided are five PhotoInterpretation (PI) kits containing rulers,dividers, simple stereo viewers, and draftinginstruments. This equipment is self-containedin a carrying case which can be used outsideof the TIIF for limited on-the-spot image in­terpretation.

Filing cabinets are provided for efficien tstorage and quick retrieval of roll and cutsheets imagery. Space is provided to storepaper maps and for storing image interpreta­tion keys.

The communication equipment within thevan consists of a telephone, a teletypewriterand a reperforator. (Figure 3, center of photo­graph) .

The TJIF is also provided with heater andair-condi tioning for main taining efficientworking conditions for the image interpretersand to keep the optical and electrical equip­ment in an optimum operating environment.

As part of the storage facility, an opticalcarry case is provided (Figure 5). This caseperforms a dual purpose. It is used to storethe optical equipment during transit for shockand vibration protection, and it serves as aconditioning environment for the optics in

96 PHOTOGRAMMETRIC ENGINEERING

very cold weather operation. It is well knownthat optics will fog when submitted to a sud­den change in temperature from cold to hot.This condition would prevent quick use of theoptical instruments in an atmosphere rising intemperature, if stored open in a cold van. Theoptical case provides for air tight atmospherewhich is first heated so that when the opticsare removed to the warmed van no fog isformed on the inside or outside surfaces.

The viewer computer described brieflypreviously is one of the most versatile itemsequipment in the TIIF. Thi~ equipment,which combines viewing and computationcapabilities, allows the image interpreter to

X" = X'/[eos t - (Y'/f) sin t]

Y" = Y'/[eos t - (yl If) sin tl eos t

wherex' = -X cos s+ Y sin sY' = - X sin s - Y cos s

s = swing anglet = tilt anglef = focal length

X, Y=image coordinatesX', Y' = corresponding image coordinates

of a reference system which hasbeen rotated to correct for swing'

X", Y" = corresponding coordinates of X'

ABSTRACT: A Tactical Image Interpretation Facility (TIIF) contains viewingequipment for extracting surveillance information from photographic, infrared,and radar imagery. The facility also includes a computer connected to a viewerfor obtaining photogrammetric information from the imagery. After the appro­priate inputs are programmed to the computer, automatic readout and imagedistortion compensation are obtained from the computer for such factors asground linear distance, heights of objects, curvilinear distances, area, targetlocation in UTM or geographic coordinates of objects within the imagery, andother parameters useful to image interpreters. These measurements can be madeto within 25 microns of the distance covered in the imagery. The facility is selfcontained in a van which is provided with air conditioning and heating tomaintain the working ambient temperature within comfortable limits.

perform Photogrammetric computationswhich would otherwise take an unreasonablelength of time to perform or, in many in­stances, it would require such complex com­putations that it would be impossible to un­dertake at the echelon of operation. Thispoint can best be illustrated by referring toFigures 6 to 10.

FIGURE 6 ILLUSTRATES a grid of uniformareas. This grid represents the results ofphotographing a similar grid using a true ver­tical photograph where theoretically no dis­tortions are present. Here, distances on theground are proportionally represented on thephotograph, so that any point may be definedin terms of simple X and Y coordinates.

Figure 7 is the resultant photograph of aground grid of Figure 6 using an obliquephotograph. In this case distortions presentin the image are caused by the position andorientation of the camera relative to theground, and are related to the swing and tiltangle as well as to the focal length of thecamera lens used. This relationship may beexpressed by the following: l

and Y' after projection to a planeof constan t scale (vertical frameequivalent) to correct for tiltangle.

FIGURE 8 IS THE resultant photograph of aground grid of Figure 6 using a panoramiccamera. Here the grid is modified by threesuper-imposed distortions. The first distortionis due to the geometry of the focal plane andsweeping action of the lens relative to theorthographic aspect of the grid being photo­graphed, and would be present even withoutmotion of the aircraft. Secondly, there is adistortion due to the time interval of angularsweep movement of the lens while the vehicleis moving at the time the photograph istaken. Thirdly, distortion is due to the IMC(image motion compensation) introduced bythe camera mechanism during the interval thephotograph is taken.

In this case expressions for the rectified co­ordinates are more complex because of theadditive effects of the distortions men­tioned.2,3 These relationships are given interms of the following:

TACTICAL IMAGE INTERPRETATIO FACILITY 97

FIG. 5. Optical carrying case.

T=tilts=swing

X, Y=image coordinatesX', Y' = rectified image coordinates

{3 = Y image coordinate after correc­tion for image motion control

! = focal lengthw = angular sweep velocity in ra­

dians per second(J = sweep angle of panoramic photo­

graph in radians

FIG. 6. Grid of uniform area simulat.ing avertical phot.ograph.

I = time of sweep in secondsV/H=ratio of aircraft velocity to aIr­

craft altitudeI', m', n' = direction cosines of image object

rays in image spaceI, m, n = direction cosines of image object

rays in object spaceOn a panoramic photo (J = X/I and thesweep time is I =(J/w

Corrections of the V-image coordinate forimage motion control is given by

(3 = Y - (VIH)(f/w) sinO

and the direction cosines of the image spacesystems of any object ray are

I' = (3((32 +F) 1/2

1Il' = fsin 01((32 +F)1/2

n' = - fcosOI((32 +F)'t 2

The image direction cosines are translatedto vertical orien ted object space directioncosines by the equations

I = - I' cos S + 1Il' sin S

m = - I' cos T sin S - 1Il' cos T cos S - n' sin T

n = - I' sin T sin S - 1Il' sin T cos S + n' cos T

and these final rectified coordinates are deter­mined by

X' = f[(V IFI)t - lin]

y' = - f(1IlIn)

Figure 9 is the resultant photograph ofFigure 6 using infrared strip photography. Inthis case the distortion is due to the line scantechnique used in IR.

I \ \

I I I , \ \ \ \I I I I I \ \ \ \

I I \ \ \ \/ / I I \ \ \ \

I / II \ \ \/ I \ \ \I I I I \ \ \ \

FIG. 7. Grid simulating an oblique photograph.

98 PHOTOGRAMMETRIC ENGINEERING

T HE DISTORTION is more evident when theterrain being photographed contains imagecomponents, such as roads, which are not per­pendicular to the line of flight. A number offactors must be considered in this case whichare evident in the following equations.4 Notethat an added correction has been includedFLS, which is the distortion due to forwardmovement of the aircraft when scan syn­chronization relative to aircraft ground veloc­ity is not constan t.

f = Iw/O

y ' = f tan (yjf)

X" = (FLS)f·X/(H - t.H) +ftanty

Y" = f( Y ' cos tx + f sin tx)

-;- (jeos tx - Y ' sin tx) cos ty

where

X, V=image coordinates'V' = partially rectified coordinate

X", V" = Rectified coordinatesf = equivalent focal lengthIx = component of til t in X -Z planety = component of tilt in V-Z planeI w = I mage wid th

() = scan angle

\

I I \ \f f \ \I I \ \I I \ \I I \

I\ II111

u

I 1\,\ I\ \ , ~ J I\ \ I I I\ \ I I I\ \ f f f

FIG. 8. Grid simulating a Panoramic photograph.

FIG. 9. Grid simulating infrared imagery.

H=Altitudeof aircraft above datumplane

.0.H=height of object above datumplane

FLS = f1igh t line scale = ratio of aircraftvelocity to film velocity

~--- - -

___ L.....--

'-~ 1.----1..-1.....--'

FIG. 10. Grid simulating side lookingRadar (SLAR).

TACTICAL IMAGE INTERPRETATION FACILITY 99

FIGURE 10 shows the resultant imagery of aside looking Radar (SLAR). In this case thegrid lines are symmetrical because usuallySLAR techniques rectify the image electronic­ally before it is displayed. 4 NOTE: The centerportion of the grid is not recorded.

The rectification may be expressed as fol­lows:

j = (Iw/R)[J

X" = (FLS)j,X/(II- M-I) + jtanty

y' = I[u/(H - MI) ]2(y" +.f) - (JItan ty)2jl/2

Y" = ± y '

The sign of the various componen ts mustbe examined to determine the sign to be as­signed to the radical. Here,

X, V=image coordinatesVi = partially rectified coordinate

X", V" = rectified coordinatesj=equivalentfocallength

ty = component of tilt in V-Z planeIw=Image widthR= RangeH=Altitude of aircraft above datum

planet1H = height of object above datum

planeFLS= flight line scale = ratio of aircraft

velocity to film velocity

These formulas have been presented to in­troduce the reader more intimately to some ofthe problems related to rectification of im­agery produced by the newly developed sen­sors. I t is suggested, however, that the readerrefer to the references indicated for a moredetailed treatment of this su bject.

THE TIIF WAS DEVELOPED by the U. S.Army Electronics Command, Fort Mon­mouth, N. J., under contract with GeneralPrecision Inc., Link Division, Binghamton,N. Y. Four R&D models were procured inthe initial development. These have provenvery successful and an additional quantity of25 units is now being manufactured.

The author is indebted to Mr. G. Young ofGeneral Precision Inc. for his contribution inthe development of the equipment, to Dr.

Lisman, USAECOM, for his help in themathematical aspects of this project, andMr. F. Ivins, USAECOM, for his help in con­ducting the evaluation of the equipment.

REFERENCES

1. MANUAL OF PHOTOGRAMMETRY, American Soci­ety of Photogrammetry.

2. ASTlA, Final Report EN-71( ), RectifyingProjection Printer, dated 16 Nov. 62. Con.tract No. DA36-039 SC·48929.

3. Photographic Science and Engineering, Vol. 5.Page 257-261 (1961). P. P. Paris and K. Leist­ner.

4. ASTrA, Final Report. Tactical Image Interpre­tation Facility. AN/TSQ-43. Contract No.DA3fi-039 SC-90888.

Notice to Authors1. Manuscripts should be typed, dou­

ble-spaced on 8! X 11 or 8 X 10! whitebond, on one side only. Refer­ences, footnotes, captions-every­thing should be double-spaced. Mar­gins should be I! inches.

2. Two copies (the original and firstcarbon) of the complete manuscriptand two sets of illustrations shouldbe submitted. The second set of il­lustrations need not be prime quality.

3. Each article should include an ab­stract, which is a digest of the article.An abstract should be 100 to 150words in length.

4. Tables should be designed to fit intoa width no more than five inches.

5. Illustrations should not be more thantwice the final print size: glossyprints of photos should be submitted.Letteri ng should be neat, and de­signed for the reduction anticipated.Please incl ude a separate list of cap­tions.

6. Formulas should be expressed assimply as possible, keeping in mindthe difficulties and limitations en­countered in setting type.

AERIAL MAPPING INSTRUMENTSKersh Prollers-Multiplexes

Ideal for Training and Photogrammetric Studies

METRIC SYSTEMS, INC.729 East Third Street, long Beach 12, California

HEmlock 775-29

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