Photogrammetry-part 1

Aerial photography – Types of aerial cameras,
Types of photographs, vertical, horizontal, oblique.

1. Topics
Photogrammetry, Part-1
•Aerialphotography–Typesofaerial
cameras,
•Typesofphotographs,vertical,horizontal,
oblique.
Prasenjit Bhowmick

2. WHAT IS PHOTOGRAMMETRY?
FROM GREEK ROOT WORDS:
-Y THE SCIENCE OF
-GRAM SOMETHING WRITTEN OR DRAWN
-METR MEASUREMENT
-PHOTOWRITING WITH LIGHT (PHOTOGRAPH)
THESCIENCEOFMAKINGMEASUREMENTS FROM
PHOTOGRAPHS .
THEMOSTCOMMON APPLICATIONOFPHOTOGRAMMETRY
ISMAKINGMAPS.
Photogrammetry
Elements of Photogrammetry

3. Elements of Photogrammetry
What is Photogrammetry ?
Measureobjects(2Dor3D)fromAerialphotographs
andstereoimages.
withoutbeingphysicallytouched.
The results can be:
•Coordinates of the required object-points
•Topographical and Thematic maps
•DEM
•Orthophoto (Rectified photographs)
Photogrammetry

4. Elements of Photogrammetry
History of Aerial Photogrammetry (Photography)
•1858,FrenchPhotographer,G.F.Tournachontookthe
firstAerialPhotographofParisCityfromaballoon.
•In1895,Laussedat,createdthefirstsuitablecamera
andprocedure,calledmetrophotographic
•In1908firstAerialPhotographwastakenfrom
Airplaneoverlemans,FrancebyWilburWright
Photogrammetry

5. Elements of Photogrammetry
•World War I (1914) Lt. Law used Airplane
to take photographs of Germany.
•World War II (1939-45) all the countries
involved in the war made extensive use of Aerial
photography
•By the year 1940, Aerial photography as applicable
to study of geology, forestry etc.
Photogrammetry

6. History of Aerial Photogrammetry (Instruments)
•Until ~1980, opto-mechanical devices were used for
Photogrammety (Hardcopy photogrammetry)))
•Hardcopy photogrammetric instruments include:
–Monocomparator
–Stereocomparator
–Rectifier
–Streoscope
–Stereoplotter
Elements of Photogrammetry
Photogrammetry

7. •The advent of the desktop computer has brought about the
transition to fully digital systems (softcopy photogrammetry)
Typical components of a softcopy photogrammetric workstation:
Elements of Photogrammetry
Photogrammetry
Computer
Storage Scanner
Keyboard
and mouse
3D cursor
Stereo monitor
Monitor
Hardcopy
output
Network

8. AERIAL CAMERA
AerialCameraisoneofthemostimportantinstrumentinthe
photgrammetry
Itisusedtoobtainthephotographsuponwhich
Photogrammetrydepends
SuccessofPhotogrammetryinrecentyearsisduetoavailability
ofhighprecisioncameras
Therequirementsofaerialmappingcamerasarequitedifferent
fromthoseofordinaryamateurcameras
Themostcommonframeorformatsizeofaerialcamerasis9in
(23cm)square
Photogrammetry

9. AERIAL CAMERA
The primary requirement of any
photogrammetricaerialcameraisalensof
highgeometricquality.
Aerialcamerasmustbecapableofexposing
greatnumberofphotographsinrapid
succession.
Musthaveshortcyclingtimes,goodlenses
andefficientshutters.
Theymustbecapableoffunctioningunderthe
mostextremeweatherconditionsandinspite
ofaircraftvibrations.
Photogrammetry

10. AERIAL CAMERA -Development
Themostimportantdevelopmentistheperfectionoflenses
ofextremelyhighresolvingpowerandalmostnegligible
distortion
Thishasgreatlyincreasedtheaccuracyofphotogrammetry
Photographsindigitalform.EarlierAerialcamerasuseroll
filmandhavemagazinecapacitiesoffrom200to400ftor
more
Photogrammetry

11. TYPES OF AERIAL CAMERAS
Fourmaintypesofaerialcamerasare
(1)Single-lensframecameras,
(2)Multi-lensframecameras,
(3)Stripcameras,
(4)Panoramiccameras.
Photogrammetry

12. 1.Single-lensframecameras,
Single-lensframecamerasarethemostcommoncamerasin
usetoday.
Usedexclusivelyinobtainingphotographsformappingpurposes
becausetheyprovidethehighestgeometricpicturequality.
Thelensisfixedrelativetothefocalplane.
Thefilmisgenerallyfixedinpositionduringexposure,
Photogrammetry

13. Single-lensframecamerasareoftenclassifiedaccordingtotheir
angularfieldofview.
Angularfieldofviewistheanglesubtendedattherearnodalpointof
thecameralensbythediagonal(d)ofthepictureformat.
Photogrammetry
(a)Normalangle(upto75°)
(b)Wideangle(75to100°)
(c)Super-wideangle(greaterthan100°)
'-Rear nodal pointof camera lens
1. Single-lens frame cameras,

14. Photogrammetry
Availableinavarietyoffocallengths.
mappingphotographyhasa6-in(152-mm)focallengthand9-
in-(23-cm)squareformat,
Otherformatinclude
3.5in(89-mm),
8.25in(2IO-mm)and
l2-in(305-mm)focallengths
The6-infocallengthwith9-informatprovidesthebestfor
geometricmapping.
Longerfocallengthsof12inareusedforaerialmosaicsand
forreconnaissanceandinterpretationpurposes.
1. Single-lens frame cameras,

15. Photogrammetry
FairchildKC-6Aaerialmappingcamera WildRC-IOaerialmappingcamera
TheRC-1Oishavingnominalfocal
lengthsof3.5in(89mm),6in(152
mm),8.25in(210mm),or12in(305
mm).
Nominal6-in-(152-mm)focal-
lengthlenses

16. Photogrammetry
12-in(305-mm)focallength.
filmcapacityis4,000ft(1,220m).
principalisadditiontotopographicmapping,
lTEKLFCLargeFormatsingle-lensframecamera
HasselbladMK-70camera
TheHasselbladcameraisasmallformat
single-lensframecamera
usedextensivelyforspacephotography.
uses70mmfilmandcanbeobtainedwith
variousfocal-lengthlenses

17. 2.Multi-lensFrameCameras
Havetwoormorelensesandexposetwoormorepictures
simultaneously
Alllensessimultaneouslyexposethesamearea,
Differentlensescontainfilms
Alsoreferredtoasmulti-spectralcameras..
Photogrammetry
MPCmultilenscamera-havingsixlenses

18. 3. Strip Cameras
Stripcamerastakescontinuousphotographofastripofterrain
Thefilmpassesoveranarrowslitopeninginthefocalplane.
Stripcamerasmayuseasinglelensortheymayhavetwo
lensestogetstereoscopiccoverage.
UsefulinRoutestudiesforHighways,railroads,pipelineetc.
Photogrammetry

19. Photogrammetry
4. Panoramic Cameras
Panoramic cameras photograph a strip of terrain from horizon to
horizon.
The strip terrain taken transverse to the direction of flight
The exposure is made by specially designed camera which scans
laterally from one side of the flight path to the other
The lateral scan angle angle may be 180
0,
in which case the
photograph contains a panorama of the terrain from horizon to horizon.
Panoramic camera are generally of two types.
1.Scan by rotating the lens
2.Scan by rotating prism in front of camera lens

20. Photogrammetry
Panoramic Cameras

21. Elements of Photogrammetry
Types of Photographs
Twobasicclassificationsofphotographsusedin
photogrammetryare
1.Terrestrial
•Takenfromgroundbasedcameras
2.Aerial
•Takenfromairbasedcameras
Photogrammetry

22. Elements of Photogrammetry
Types of Aerial Photographs
Aerial Photographs can be classified in the following
manner
1.Accordingtoorientationofcameraaxis
2.AccordingtoLenssystem
3.AccordingFilmproperties
Photogrammetry

23. 1. According to orientation of camera axis
The vertical
The oblique
•dependsupontheangleofthecamera
•withrespecttotheearth'ssurface
Elements of Photogrammetry
Photogrammetry

24. Vertical Photographs
Camera points as straight down as possible
Allowable tolerance is usually ±3°from the plumb line
Plumb line coincident with the camera axis
A vertical photograph has the following characteristics
The lens axis is perpendicular to the surface of the
earth
It covers a relatively small area
The shape of the photos closely a square or rectangle
Distance and directions of maps if taken over flat
terrain
Relief is not readily apparent
Elements of Photogrammetry
Photogrammetry

25. Relationship of the vertical aerial photograph with the ground
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26. V
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27. Low Oblique Photographs
Camera inclined about 30°from the vertical
-Characteristics -
Covers a relatively large area
Ground area covered is a trapezoid, although the
photo is square or rectangular
It have more familiar than viewing from the top
of a high hill or tall building
No distance can measure with Scale.
Azimuth cannot be measured
Relief is perceptible but distorted
It does not show the horizon
Elements of Photogrammetry
Photogrammetry

28. Relationship of low oblique photograph to the ground
Elements of Photogrammetry
Photogrammetry

29. L
O
W
O
B
L
I
Q
U
E
P
H
O
T
O
G
R
A
P
H
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30. High Oblique Photographs
Taken with the camera inclined about 60°from the
vertical
Limited military application
-Characteristics -
Covers a very large area (not all usable)
Ground area covered is a trapezoid, but the photograph
is square or rectangular
Distances and directions are not measured
Relief may be quite discernible but distorted as in any
oblique view.
The horizon is always visible.
Elements of Photogrammetry
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31. High oblique photograph
Elements of Photogrammetry
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32. Vertical aerial photograph.
Low-oblique aerial photograph.
High-oblique aerial photograph
Pc: Kahola, Kansas.
Elements of Photogrammetry
Photogrammetry