This document discusses methods for calculating the heights of objects like trees and buildings from aerial photos. It describes the relief/radial displacement method, where the displacement between the top and bottom of an object seen in a single aerial photo is used along with the distance from the principal point to determine height. It explains that relief displacement occurs due to perspective projection and varies with object elevation relative to the datum. An example problem demonstrates using measured displacement and distance to calculate an object's height given the flying height.

1. Presentation
on
Presented by
Mr .Amol V. Ghogare
Assistant Professor, Civil Engineering Dept.
SRES, SCOE, Kopargaon
.

2. Calculating Object Heights
• As with calculating scale, there are multiple methods to determine the
height of tall objects (e.g. trees or buildings) in aerial photos. In single
aerial photos the two primary methods are the relief/radial
displacement method and the shadow methods.
• Relief/Radial Displacement Method
 The magnitude of the displacement in the image between the top and
the bottom of an object is known as its relief displacement .
 Relief Displacement exists because photos are a perspective projection.
 It is related to the height of the object and the distance of the object
from the principal point.
 This method can only be used if the object that is being measured is be
far enough from the principal point to measure the displacement and
the top and bottom of the object are visible in the photo.

3. Relief displacement is scale variation on aerial photographs caused by
variations in terrain elevation.

8. Relief displacement
Any objects that are higher or lower than the principal
point are displaced from its true planimetric (x,y)
location on a vertical aerial photograph. This
displacement is referred to as relief displacement or
terrain distortion.
The relief displacement is outward from the principal
point for objects whose elevations are above the local
datum, and toward the principal point for objects
whose elevation are below the local datum
The direction of relief displacement is radial from the
principal point.

11. The lower the elevation of an object, the more it will be
displaced toward the principal point. This effect, called
relief displacement.

12. Measurement of Object Height From A Single
Aerial Photograph Based on Relief Displacement

13. Relief/Radial Displacement Method
Use this to determine the height of object

18. • Example: The length of a a displaced building is measured at
2.01 mm and the radial distance to the principal point is
56.43 mm. If the the flying height about the surface is 1220
m, what is the height of the building?
Sol:-

19. Thank you