Help for MARSFAKEDISP

PURPOSE:
Simple program to compute a "fake" disparity map by projecting the
camera models to a surface.

This program is intended as a replacement for marsjplstereo when used
as a prelude to marscor3.  Instead of actually correlating the images,
it uses the camera models and surface model to compute an "ideal" disparity
map, assuming the scene exactly matches the surface.

This enables marscor3 to be run on non-linearized stereo images.  With
enough downsampling ("pyramid" levels), this synthetic disparity map gets
close enough for marscor3 to find tiepoints and generate the full disparity
map in most cases.

The output format is the same as marsjplstereo.

In theory, using -rover as a coordinate system should generate the best
surface in most cases.  (Unlike most other mars* programs, -rover causes
the ground/normal values to be interpreted in rover frame).  However,
early testing has shown this not to be the case.  Some images get worse
(when it seems they should get better), yet other images require -rover.

As a compromise, -average can be specified.  This causes the surface model
to be the average of the site's  and specified frame's (usually rover) models.
Note that both site and rover frame models look at the same parameters.  It
is somewhat unclear why this works, but it seems to in early tests.

A pyramid level of 4 should typically be given for 1024x1024 images.  This
results in a 64x64 output.

EXECUTION:
marsjplstereo inp=(left,right) out=disparity pyr=4 -rover -average


METHOD:
marsfakedisp takes each pixel in the left eye, projects it down to the
surface, and projects it back into the right eye.  The resulting coordinate
(adjusted for pyramid level) becomes the disparity value in the output file.

HISTORY:
Mar. 04  Initial version: B. Deen
COGNIZANT PROGRAMMER:  Bob Deen