mapping from aerial images is a proven science, the positional accuracy
is easily predicted when standard constants are met:
calibrated precision 9" x 9" aerial camera
2. proper flying height above mean terrain
3. Precision photogrammetric stereo-plotter
4. reliable ground control survey and well defined targets
provides mapping that will comply with accuracy standards for large-scale
maps as developed by Specifications and Standards Committee of the
American Society for Photogrammetry and Remote Sensing (ASPRS).
MAP ACCURACY is defined as rms error in terms of projects
planimetric survey (x,y) for checked points as determined at full (ground)
scale of the map. The rms error is the cumulative result of all errors
including those introduced by the process of ground control surveys,
map compilation and final extraction of ground dimensions from the map.
The limiting horizontal rms errors shown below for Class 1 maps are
the maximum permissible errors established by this standard for tests
on well defined points only.
MAP ACCURACY is defined as the rms error in the elevation
in terms of the project's evaluation datum for well defined points only.
For Class 1, maps, the limiting rms error in evaluation is set by the
standard ine-third the indicated contour interval for well defined points
only. Spot elevations shall be shown on the map within a limiting rms
error of one-sixth of the contour interval.