surveying ii module iii class 3

ModModule IIIule III

AeAerialrial

photogphotogrammetryrammetry

Ground co-ordinates for vertical photographs

If the ground coordinates of two points, A and B are given (XA, YA) and (XB, YB ), then the length L between the two points is given by

2 2

A B A BL X X Y Y

where

The flying height H can be calculated from these values

DISTORTION AND DISPLACEMENT

distortion in aerial photography is defined as any shift in the position of an image on a photograph that alters the perspective characteristics of the image

displacement is any shift in the position of an image on a photograph that does not alter the perspective characteristics of the photograph.

Image displacementon vertical airphotos

• Relief displacement The displacement of the point a on the

photograph from its true position, due to height, is called the height or relief displacement or relief distortion (RD).

This distortion is due to the perspective geometry.

IMAGE DISPLACEMENT on vertical airphotos