and Uses of orthophotos
do not contain
the scale, tilt and
relief distortions .
(images of features)and
maps(utilizes lines and symbols) are similar
are produced from perspective
photos through a process called differential
eliminates image displacements due to
photographic tilt and relief
must obviously be removed, but
variations in terrain should also be corrected
geometric transformations are applied
to the image, depending on the perspective
and terrain corrections required on a particular
part of the image.
Orthophotos can be used as maps for making direct
measurements of directions, angles, positions and area.
Orthophotos have the pictorial qualities of air photos because
the images of an infinite number of ground objects can be
recognized and identified.
Orthophotos are used as base-maps for plotting field
Using orthophotos , engineers are better able to
communicate with property owners to discuss right- of-way
purchase, access to property etc.
Ortho-photos are commonly used in geographic information
systems, such as are used by mapping agencies
1.Those which produce images by direct
2.Those which produces images
A 6 inch ( 150mm) focal length camera should be used.
End lap (60%)and side lap(30%) for orthophotography
should generally be about as same as that for mapping