Help for GT2RPC

PURPOSE
     A mapped image usually doesn't need an RPC, but a simplified RPC can
represent the linear mapping.  No elevation is needed since a mapped image is
always presumed ortho.

DO NOT USE THIS ROUTINE FOR AN IMAGE WHICH IS NOT ORTHO AND MAY HAVE A GEOTIFF
LABEL AS AN APPROXIMATE MAPPING.
	   
CALL
     gt2rpc INPUT
  WHERE:
     INPUT          is an image file with a GeoTIFF mapping label.
 
OPERATION

    The mapping label is used to produce a grid and the grid is solved for
an RPC.

PERFORMANCE

Expect about 1 seconds.

Restrictions
------------

The input must have a GeoTIFF label.

DO NOT USE THIS ROUTINE FOR AN IMAGE WHICH IS NOT ORTHO AND MAY HAVE A GEOTIFF
LABEL AS AN APPROXIMATE MAPPING.

Original Programmer: A. L. Zobrist, 11 Dec, 2008
Current Cognizant Programmer: A. L. Zobrist

REVISIONS
2022-08-10 B. Crocco afids to opensource (untested)

PARAMETERS: