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Photography .
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FIG. 3. PRESENT WORKING SYSTEM
season and the following recess work from the subsequent operations
in the second field season. The models from existing photography
in the areas where projects for development are likely to be taken
up should be controlled by E D M traverse or trilateration and
aerial triangulation by analytical methods. The controlled models
should be stored for use for the planimetry of the area taken up
for development. The contour survey can then be done by ground
methods or on large scale photographs ordered as soon as the pro
ject details are finalised.
Actually the contour interval for most engineering surveys is
so small that ground contouring will work out to be comparatively
less time consuming. However, the economics of both the methods
can be worked out in each case and the most suitable one can be
adopted.
STANDARDIZATION OP AERIAL PHOTOGRAPHY SCALES
The scales of aerial photography should be standardized keeping
in view the cost and time of map production, constraints of flying
heights and requirements of indentors. The following scales are
recommended.
