Help for XYZSUN

PURPOSE:
To convert an ascii tiepoints file written by tracker3 into an expanded
ascii file containing x,y,z,latitude,longitude,radius for the sun.
This program supports solar imagery only.
It converts image coordinates from a stereo pair into absolute solar 
coordinates.
(Does not run correctly on SGI, no known cause).

EXECUTION:
xyzsun inp=tpts out=tptsxyz


METHOD:
xyzsun reads the times in the ascii header and constructs via the farenc 
algorithm om matrices and rs vectors for the two images.
It then computes the intersection of view rays for each tiepoint.
The xyz points are stored in the output ascii file.
The output ascii file has the same records as the input file but contains
in addition the xyz solar coordinates.

The input file contains the following information:
linel   left image line
sampl   left image sample
liner   right image line
sampr   right image sample
dnl     left image dn
dnr     right image dn

The output file contains the following information:
linel   left image line
sampl   left image sample
liner   right image line
sampr   right image sample
dnl     left image dn
dnr     right image dn
x       sun cartesian x in km   
y       sun cartesian y in km   
z       sun cartesian z in km   
lat     sun centric latitude in degrees
lon     sun centric longitude in degrees west
r       distance from sun center in km
dr      distance above apparent surface
error   miss distance between view rays in km

The time for the left two columns is recorded in record 2 of the tiepoints
file in the form: asfd19920112044820.vic where the format is: yyyymmddhhmmss.
The time for columns 3 & 4 is in record 3. These are placed there by tracker3.
The time strings are the labels of the two input files to tracker3.

The SPICE is consulted to determine the solar sub earth point at each time.
The program assumes that both images are centered at the same image 
coordinates.


HISTORY:
1-1-97  J Lorre. 
15-Jan-2013 -lwk- fixed continued CHARACTER constant for new compiler flag on Solaris;
                  replaced SPICE initializations with call to init_spice

COGNIZANT PROGRAMMER:  Lucas Kamp