This is only about to konow what is photogrammetry not detialed imformation

1. PHOTOGRAMMETRY
G.CHANDRA SEKHAR REDDY
M.Tech(GIS)
NIIT UNIVERSITY

2.  VERY PRECISE
 3D REPRESENTATION
 TIME EFFECTIVE
 COST EFFECTIVE
 BASED ON WELL ESTABLISHED AND
TESTED ALGORITHMS
 LESS MANUAL EFFORT
 MORE GEOGRAPHIC FIDELITY

3.  Photos – light
 Gramma – to draw
 Metron – to measure
“Photogrammetry is the technique of measuring objects
from photographs”
“The art, science and technology of obtaining
reliable spatial information about physical objects
and the environment through the processes of
recording, measuring and interpreting image data”

4.  Aerial photography is the taking of photographs of the
ground from an elevated position. The term usually
refers to images in which the camera is not supported
by a ground-based structure
 Close-range Photogrammetry the camera is close to the
subject and is typically hand held or on a tripod

5. PROCESS FLOW
 RAW DATA FORM CLIENT (SCANS)
 AERIAL TRIANGULATION
 DATA CAPTURING
 DEM GENARATION
 CONTOUR GENARATION
 ORTHOPHOTO GENARATION

6.  In Aerial Photogrammetry the camera is mounted in an
aircraft and is usually pointed vertically towards the
ground
 Multiple overlapping photos of the ground are taken as
the aircraft flies along a flight path
 These photos are processed in a stereo-plotter

7.  Adjacent but
overlapping aerial
photos are called
stereo-pairs and
are needed to
determine parallax
and stereo/3D
viewing

8. AERIALTRIANGULATION

9.  Overlapping
photography
 Endlap - ~60%
 Sidelap - ~20-30%

10.  RASTER AND VECTOR DATA
 THE DATA PREPARATION
 PLANMETRIC FEATURES
 DATA OUTPUT

11. Raster data are described by a cell grid, one value per cell
Vector Raster
Point
Line
Zone of cells
Polygon

12.  Buildings
 Transportation Features
 Hydro Features
 Utilities
 Vegetation
 Breaklines
 DTM points
 Bridges

13. 1
3

14. Stereo Image Vector Data

15.  There is no common usage of the terms digital
elevation model (DEM), digital terrain model (DTM) and
digital surface model (DSM) in scientific literature
 The digital terrain model represents the bare ground
surface
 The term Digital Elevation Model is often used as a
generic term for DSMs and DTMs, only representing
height information without any further definition about
the surface

17.  Contour lines are lines drawn on a map connecting
points of equal elevation
 Contour lines are useful because they allow us to show
the shape of the land surface (topography) on a map
 This vertical spacing is referred to as the contour
interval
 If the contour interval is 10 ft. Each the contour lines
was a multiple of 10 ft.( i.e. 0, 10, 20, 30)
 In areas with high relief the contour interval is usually
larger

19. DATA FOR THE 3D CITY MODELS
 The 3D city models contain data, which is related to the
Spatial objects
 Those objects are generally topography, buildings,
transportation, plant cover, infrastructure and other
details related to the goal of application
 3D city models are focused on buildings however it may
contain roads, green cover, trees etc. according to the
usage of model

20. 3D BUILDING MODEL
The constructed 3D model

21. Photogrammetry …. Lecture 11
Dr. Steve Ramroop

22. ORTHO PHOTO GENERATION

23. ORTHO PHOTO GENERATION
 Ortophotos are photographs that have been
corrected for distortions
 Distortions from the camera lens, and relief
 To use these orthophoto images as a map, it
is of great importance to provide orthophoto
images in high level of accuracy

24. ORTHOIMAGE

25. ORTHOIMAGE
location of bridges uncorrected and corrected for
height differences against the road below

26. conclusion
3D Representation and Visualization of real world is
only possible with photogrammetry.The output of
photogrammetry is typically a map Many of the
maps we use today are created with
photogrammetry and photographs taken from
aircraft.

27. THANK YOU