Help for GTWARPXD

PURPOSE


  coverref case with distort file not tested yet
  
     GTWARPXD reads the GeoTIFF label of a "master" or "reference" image,
     then reads the GeoTIFF label of the input image.  It calculates
     a set of GEOMV parameters from these and then calls GEOMV to warp
     the input image to match the mapping of the "reference" image.
     
     1.  The keyword 'coverinp causes the procedure to map all of the
     input image to an output image that will just contain it.   The
     keyword gorewid allows the user to specify a zero-filled margin
     to make the output a little larger (or negative trims smaller).
	
     2.  The keyword 'coverref causes the procedure to map the input
     image to an output image that exactly matches the "reference" image.
     Some parts of the input can be lost, or huge areas of zero-fill
     could be added to make the images match.  The gorewid keyword has
     no effect in this case.
     
     A sequence of post-mapping distortions can be added with the
     parameter DISTORT.  These will be applied in sequence to the
     warp grid developed from the mapping.  These distortions are
     all given in pixel (newline,newsamp,oldline,oldsamp) point pairs
     in the reference image coordinate space.  The points can be
     irregular (tieconv is used).  THE NET RESULT IS THAT A SINGLE
     IMAGE GEOMV WILL BE APPLIED TO AVOID MULTIPLE IMAGE RESAMPLINGS.
     
     See the help for the parameter DISTORT for special cases to
     1.  save time when a sequence of calls is made
     2.  to save the combined grid from a multi-distort call
     3.  to do a map projection change at the end of processing

CALL
     gtwarpxd INPUT OUTPUT REF '(QUALIFIERS) PARAMS
  WHERE:
     INPUT          is the input data set (must have a GeoTIFF label).
     OUTPUT         is the output data set (will have a GeoTIFF label).
     REF            is the reference data set (must have a GeoTIFF label).
     QUALIFIERS     consist of any of the following keywords:
          COVERINP         smallest output that covers the input geographic area
          COVERREF         output exactly matches the reference image.
     PARAMS         interp,nah,nav,gorewid.

  
OPERATION

First, for the 'coverinp case only, the procedure calculates the
extrema of the input in the output pixel space.  For the 'coverref
case, the extrema are the boundaries of the reference image.

Then the procedure calculates (in an ibis file) a grid that is
rectangular in the output space using the extrema calculated above.
Then new columns are calculated using the GeoTIFF map projections
in the labels of the input and reference images yielding the grid
in the input image.  Then GEOMV is called to calculate the result.

Each distortion is calculated by the following steps (coverinp case):

1.  warp grid is calculated to (sl,ss,nl,ns).
2.  tieconv is applied to the distortion points using (sl,ss,nl,ns)
    as the bounding box.
3.  adjustments are calculated for the four edges of the bounding box.
4.  (newsl,newss,newnl,newns) are calculated by the adjustments.
5.  tieconv is applied again to the distortion points using (newsl,
    newss,newnl,newns) as the bounding box.
6.  the warp grid from step 1 is composed with the grid from step 5
    using the program gridcomp.
7.  steps 2 through 6 are repeated for each distortion input with
    the composed grid now replacing the grid started in step 1.
8.  geomv is now applied with the composed grid and (newsl,newss,
    newnl,newns).  The reference input is unchanged.


PERFORMANCE

The time will consist of the IBIS file grid generation and mapping
which could be minutes for a 1000 x 1000 grid plus the GEOMV time.
See the GEOMV document for GEOMV timing (a 4000 by 4000 image was
transformed by a 500 x 500 grid in 99 seconds on a SPARCstation 20.
Reducing the grid to 30 x 30 cut the time to 39 seconds.  This shows
that the use of a large grid doesn't penalize the time too much, 1999).

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

The input and reference images must have GeoTIFF labels.


Original Programmer: A. L. Zobrist, 25 Jun, 2000
Current Cognizant Programmer: A. L. Zobrist

HISTORY:
2002-01-23 A. L. Zobrist
2007-04-26 A. L. Zobrist - Got rid of geomv3x3 call, changed memsize use.
2021-05-24 W. L. Bunch - migrated from AFIDS

PARAMETERS: