coyote: CGFINDMAPBOUNDARY

Description
Utility routine to find the map projection grid boundary from a file,
if it is possible to do so. Currently works with GeoTIFF files, CF 1.4
compliant netCDF files, and GPD files created with the GPD_Viewer software
from the Catatlyst Library.
Categories
Utility
Returns
The return value is either a 1, indicating a boundary can be found, or a 0 indicating
that the boundary could not be found.
Params
filename: in, required, type='string'
   The name of a filename to open to see if a projected map grid boundary can be found.
boundary: out, optional, type=float
   The boundary of the image in projected meter space, in the form [x0,y0,x1,y1].
Keywords
use_latlon:  in, optional, type=boolean, default=0
    If the filename is a netCDF file, set this keyword to force the boundary 
    to be determined by reading the include latitude/longitude arrays.
utm_south: in, optional, type=boolean, default=0
    Set this keyword to add 10e6 to each of the Y values. This is sometimes
    necessary with LandSat images in the Southern hemisphere, where the Y values
    are given in negative values to indicate southern UTM zones.
xrange: out, optional, type=float
    A two element vector: boundary[[0,2]]
yrange: out, optional, type=float
    A two element vector: boundary[[1,3]]
Author
FANNING SOFTWARE CONSULTING::
   David W. Fanning 
   1645 Sheely Drive
   Fort Collins, CO 80526 USA
   Phone: 970-221-0438
   E-mail: david@idlcoyote.com
   Coyote's Guide to IDL Programming: http://www.idlcoyote.com
History
Written by: David W. Fanning, 23 February 2010.::
   Added XRANGE and YRANGE keywords. 25 February 2010. DWF
   Added USE_LATLON keyword for finding boundary of netCDF files containing latitude
      and longitude arrays. 6 April 2010. DWF.
   Added UTM_SOUTH keyword to handle Landsat dat in UTM projections in GeoTiff files
      that have to have 10e6 added to Y values to make them work in IDL. 14 Aug 2012. DWF.
   Renamed cgFindMapBoundary from FindMapBoundary. 21 Aug 2012. DWF.
   Changed reference to NCDF_Coord to cgNCDFMap. 28 Oct 2012. DWF.
Copyright
Copyright (c) 2012, Fanning Software Consulting, Inc.