PhotogrammetryPhotogrammetryCE 426CE 426 IntroductionIntroductionDefnition of Photogrammetry:Defnition of Photogrammetry: the art, the art, science, and technology of obtaining science, and technology of obtaining information about physical obects and information about physical obects and the en!ironment by photographic and the en!ironment by photographic and electromagnetic images"electromagnetic images" #asic Information#asic Information$apping from aerial photos is the best $apping from aerial photos is the best mapping procedure yet de!eloped for mapping procedure yet de!eloped for most large proects"most large proects"%sed successfully for maps !arying in scale %sed successfully for maps !arying in scale from &:&,''',''' &:&2' (ith contour from &:&,''',''' &:&2' (ith contour inter!als as small as & foot"inter!als as small as & foot")opographic mapping is the most common )opographic mapping is the most common form" * %"+","+ updated and done this (ay"form" * %"+","+ updated and done this (ay"%sed to reconstruct a scaled -.dimensional %sed to reconstruct a scaled -.dimensional optical model of the lands surface using a optical model of the lands surface using a stereoplotterstereoplotter"" #asic Information#asic Information%ses: /erial photos%ses: /erial photos/id: geological in!estigations, soil /id: geological in!estigations, soil sur!eys, land sur!eys, ta0 mapping, sur!eys, land sur!eys, ta0 mapping, reconnaissance and military intelligence, reconnaissance and military intelligence, urban and regional de!elopment, urban and regional de!elopment, transportation system in!estigations, transportation system in!estigations, 1uantity estimates, shore erosion, etc"1uantity estimates, shore erosion, etc"$athematical methods ha!e been $athematical methods ha!e been de!eloped to ma2e precise -.dimensional de!eloped to ma2e precise -.dimensional measurements from photos"measurements from photos"Phototriangulation: -.dimensional positioningPhototriangulation: -.dimensional positioning of sur!ey stations" of sur!ey stations" #asic Information Continued#asic Information ContinuedPhoto has been used to ta2e geometric Photo has been used to ta2e geometric measurements of human bodies, artifcial measurements of human bodies, artifcial human hearts, large radio telescopes, human hearts, large radio telescopes, ships, dams, buildings and !ery accurate ships, dams, buildings and !ery accurate reproductions"reproductions"In general it is not economical for In general it is not economical for small proects * the cost brea2 e!en small proects * the cost brea2 e!en point is some(here bet(een -' * &'' point is some(here bet(een -' * &'' acres depending on the situation"acres depending on the situation" #asic Information#asic InformationPhotogrammetry can not be used Photogrammetry can not be used successfully o!er the follo(ing types of successfully o!er the follo(ing types of terrain"terrain"Desert or plains areas, sandy beaches, Desert or plains areas, sandy beaches, and sno( * the photograph as uniform and sno( * the photograph as uniform shades (ith little te0ture"shades (ith little te0ture"Deep canyons or high buildings that Deep canyons or high buildings that conceal ground surface"conceal ground surface"/reas co!ered by dense forest"/reas co!ered by dense forest" 2 #asic Categories 2 #asic Categories $etrical photogrammetry * obtaining $etrical photogrammetry * obtaining measurements from photos from measurements from photos from (hich ground positions, ele!ations, (hich ground positions, ele!ations, distances, areas, and !olumes can be distances, areas, and !olumes can be computed and topographic or computed and topographic or planimetric maps can be made"planimetric maps can be made"Photo interpretation * e!aluation of Photo interpretation * e!aluation of e0isting features in a 1ualitati!e e0isting features in a 1ualitati!e manner"manner" )ypes of Photogrammetry)ypes of Photogrammetry/erial * series of photographs of an /erial * series of photographs of an area of terrain in se1uence using a area of terrain in se1uence using a precision camera"precision camera")errestrial * photos ta2en from a f0ed )errestrial * photos ta2en from a f0ed and usually 2no(n position on or near and usually 2no(n position on or near the ground (ith the camera a0is the ground (ith the camera a0is hori3ontal or nearly so"hori3ontal or nearly so"Close range * camera close to obect Close range * camera close to obect being obser!ed" $ost often used (hen being obser!ed" $ost often used (hen direct measurement is impractical"direct measurement is impractical" 4istory4istory)he frst use of photogrammetry (as by /rago, )he frst use of photogrammetry (as by /rago, a 5rench geodesist, in &64'" )his included a 5rench geodesist, in &64'" )his included topographic and terrestrial"topographic and terrestrial")he frst aerial photogrammetry (as by the )he frst aerial photogrammetry (as by the 5rench in &647 using 2ites and balloons"5rench in &647 using 2ites and balloons"8aussedat 95rench: * father of photogrammetry"8aussedat 95rench: * father of photogrammetry"&&st st in ;" /merica * De!ille, +ur!eyor ,eneral of in ;" /merica * De!ille, +ur!eyor ,eneral of Canada"Canada"%"+","+" adopted photogrammetry as mapping %"+","+" adopted photogrammetry as mapping process in &674 * mapping border bet(een process in &674 * mapping border bet(een Canada and /las2a"Canada and /las2a" 4istory 4istory /irplanes brought great change to /irplanes brought great change to photogrammetry"photogrammetry"&&st st used in &7&-"used in &7&-"%sed e0tensi!ely in erence in ground ele!ation and Kying height" and Kying height"8onger focal length reduces scale !ariation" 8onger focal length reduces scale !ariation"If Kying height remains constant and groundIf Kying height remains constant and ground ele!ation increases the area co!ered by photoele!ation increases the area co!ered by photo becomes less" becomes less"?!erlap becomes less ?!erlap becomes lessCie(fnder needed to control o!erlap and Kightline spacing,Cie(fnder needed to control o!erlap and Kightline spacing, thus eliminating possible gaps" thus eliminating possible gaps"4"4"Aelief displacementAelief displacement/>ects mosaics most" />ects mosaics most"8arge amount of relief displacement (ill ma2e it diIcult to8arge amount of relief displacement (ill ma2e it diIcult to form continuous picture desired in mosaics" form continuous picture desired in mosaics" Elements of PlanningElements of PlanningAelief displacement decreases as Kying heightAelief displacement decreases as Kying height increases, the focal length must also be increased" increases, the focal length must also be increased"Aelief displacement has no ad!erse a>ect on mapAelief displacement has no ad!erse a>ect on map ma2ing (ith stereo" ma2ing (ith stereo"