Help for GTAPPEND

PURPOSE:
gtappend combines up to 48 datasets into a single dataset with append format.
This is equivalent to concatenating the input images in a top to bottom
fashion.  The program works like VICAR routine APPEND if there are no
GeoTIFF labels.  If there are, the GeoTIFF labels of the inputs are read
for any of several mistakes:

1.  any differences in mapping
2.  a difference in scale
3.  a difference in image rotation with respect to North
4.  an error of offset, the images must butt together geographically
    exactly as they are concatenated in the image sense.
    
If any of these errors occur, the program aborts with an appropriate
error message.

A correct GeoTIFF label is attached to the output (it will be a copy
of the first (topmost) input since its offset is (1,1) in the VICAR
pixel referencing system.

If a SIZE parameter is used, it applies to all of the input images.
The SIZE parameter is not allowed in GeoTIFF label cases.

EXECUTION:

Example

gtappend INP=(A,B,C) OUT=D  will put images A, B, and C top-to-bottom
to form D.

OPERATION:
gtappend combines datasets in the following manner:

First, the data sets are checked for GeoTIFF labels, and if they are
present, a number of conditions must be satisfied or the program
aborts:

	1.  any differences in mapping
2.  a difference in scale
3.  a difference in image rotation with respect to North
4.  an error of offset, the images must butt together geographically
    exactly as they are concatenated in the image sense.
5.  if the first image has a GeoTIFF label then all must have one

The first input is read and copied to output (modified by SIZE if given).
Then the second image is read and copying to the output continues.  If
any of the images have a different NS, or a different pixel size, the
program abortw with an error message.

The program uses dynamic allocation of buffers in the C programming
language, so truly colossal images can be combined (for example, an
output image of 30 x 10,000,000) would not be a problem.

 TIMING: 

As fast as VICAR can read and write the lines.  

 ORIGINAL PROGRAMMER:    A. Zobrist          29 Oct 1999
 COGNIZANT PROGRAMMER:   Barbara McGuffie    29 Oct 1999
 
 REVISION HISTORY
  1999-10-29 AZ - Initial version
  2007-12-29 WLB - Switched to USES_ANSI_C AND LIB_CARTO; misc cleanup
  2015-09-10 WLB - Fixed headers for MIPL build
  2016-01-13 WLB - Replaced printfs with zifmessages
  2019-09-04 WLB - IDS-7922 - Initialized some variables.