Help for IBISGCP

PURPOSE:

IBISGCP outputs Ground-Control Points to an IBIS file for use in registering
the elements of a mosaic.  IBISGCP is a multimission program and can be used
process images from Cassini, Galileo, Voyager, and Viking Orbiter.

EXECUTION:
	   IBISGCP  inp=nav  out=gcp  project=GLL  id=(5,8)
or
	   IBISGCP  out=gcp  project=GLL  id=(5,8)
              target=EARTH  camera=(1,1)  	      scet=(1990,345,14,6,22,0,  		    1990,345,22,16,780,0)
where
	nav is an input IBIS SEDR file containing navigation data for each
	    image in a mosaic (see program IBISNAV),
	gcp is an output file containing the ground-control points from
	    one or more reference images in the mosaic.
	project is CASSI, GLL, VGR-1, VGR-2, or VIKOR,
	id is a list of frame sequence numbers corresponding to the position
	    of each reference image in the IBIS SEDR file.

If the IBIS SEDR file is not input, the navigation data will be retrieved via
the MIPS SPICE server.  This requires that the target be specified, and that
each reference image be identified by camera serial number and spacecraft-event
time (see TARGET, CAMERA and SCET parameters).

OPERATION:

IBISGCP outputs ground-control points for use in registering the elements of a
mosaic.  For Voyager refer to procedure MANUAL2.COM.  For Galileo refer to
procedure MANUAL3.COM.  Note that both of these procedures are currently
unported (and therefore available only via the Harvest CM system).

Ground-control points are points on a target body whose latitude-longitude
coordinates are known.  IBISGCP creates psuedo ground-control points by
assuming that the navigation data for each of the reference images is perfect
(i.e. contains no errors).  The reference images are normally images which
have been previously navigated to improve their camera pointing knowledge.
Images with visible limbs are usually used as reference images since these may
be navigated by fitting the limb (see programs FARENC and NAV).

The reference images are specified in one of two ways:

1: by inputing an IBIS SEDR file and specifying the frame sequence number
   of each reference image within this file (see ID parameter).
2: by specifying their camera IDs and spacecraft-event times (see CAMERA and
   SCET paramters).

   navigation data via the SPICE server.

Method #1 is normally used.  In this mode, IBISNAV is first run to create the
IBIS SEDR file.  This file will contain the navigation data for all frames
comprising the mosaic.

If method #2 is used, IBISGCP retrieves the navigation data for each reference
image via the MIPS SPICE server.  This requires that the target-body name
be specified (see TARGET parameter).  Moreover, the spacecraft-event time and
camera serial number for each reference image must be specified (see SCET and
CAMERA parameters).  For unknown reasons, the ID parameter is also required,
even though the corresponding IBIS SEDR file may not even exist.

For either method, the spacecraft ID must be specified (see MISSION parameter).

Ground-control points are selected in each reference image so that they form
a grid pattern over the image (see LINC and SINC parameters).  The line-sample
coordinates of each grid point is converted to latitude-longitude coordinates.
If the point is not on the target body, it is skipped.

All points from the same reference image are equally precise.  The actual
precision is solely determined by the accuracy of the navigation source.

The ground-control points are output to an IBIS file suitable for input to
program OMC or OMCOR2.  The IBIS file has 5 "columns" and N "rows", where N is
the number of ground-control points.  The columns are:

	1	frame sequence number (from ID parameter)
	2	line coordinate
	3	sample coordinate
	4	latitude coordinate
	5	longitude coordinate

GEOMETRIC DISTORTIONS:

For Voyager and Viking Orbiter, the reference images are assumed to be
geometrically corrected.  Thus, the line-sample coordinates for the ground
control points are assumed to be in object space.

For all later missions (Cassini, Galileo), the reference images are assumed
to be geometricall uncorrected.  Thus, the line-sample coordinates for the
ground control points are assumed to be in image space.

These assumptions effect the resulting latitude-longitude computations.  The
keyword 'OBJECT may be used to specify an object-space output.  Note that it
is not possible to image-space coordinates for Voyager or Viking Orbiter since
the reseau locations are unknown.

PROGRAM HISTORY:

Written by:         C. AVIS, 2/89
Current Cognizant Programmer:  Gary Yagi, Jan 31, 2003
Revisions:

When      Who  What
--------- ---  ---------------------------------------------------------------
Jan 31 03 GMY  Fixed Linux compile errors.  Updated to support Cassini.
	       Fixed Voyager to reflect use of SPICE instead of SEDR.
	       Major revision of documentation.
Dec 09 96 SMC  * Modified for summation mode support                 (FR89818)
               * Parameter PLANET is changed to TARGET
               * Modified to call GETSPICE3 instead of GETSPICE          (DFR)
               * Discovered that MSEDR did not correctly assign the OM and
                 RS to DATA buffer, fixed.                               (DFR)
               * Discovered that subroutine FROMEULER is incorrect, the one
                 from MOSPLOT is copied and tested.                      (DFR)
               * Discovered that the CONVEV DATA buffer is not complete if
                 the program is given an IBISNAV file, fixed.            (DFR)
	

PARAMETERS: