
To provide map projections support your first need to make sure the libproj4
library is installed.  The source code for this can be found at:

http://members.verizon.net/~vze2hc4d/proj4/lbp4_050319S.tar.gz

The "--with-libproj4=DIR" switch in configure can be used give the location
of this library.


The following additional PRO files must be acquired and placed in the
appropriate directories:

map_continents.pro
map_grid.pro
map_horizon.pro
map_image.pro
map_patch.pro
map_point_valid.pro
map_proj_image.pro
map_proj_info.pro
map_proj_init_commonblock.pro
map_proj_init_common.pro
map_proj_init.pro
map_set.pro
map_struct_append.pro

These files can be found by entering the following URL into your web
browser:

http://idlastro.gsfc.nasa.gov/cgi-bin/idllibsrch?keyword=map_

clicking on the appropriate file and saving it to your computer.

They can be placed in any directory within you GDL path.


To provide support for MAP_CONTINENTS the database files must be
downloaded:

blow.dat
blow.ndx
clow.dat
clow.ndx
plow.dat
plow.ndx
rlow.dat
rlow.ndx

These files can be found at:

http://comm.nsdl.org/viewcvs/viewcvs.cgi/ddtoolkitnfndry/ETA_Viewer/Development/resource/maps/low/

These files should be placed in the "resource/maps/low" subdirectory
of the !DIR directory which can be found by starting GDL and printing
the !DIR system variable.

Note: Only low-resolution boundaries are currently supported.


The following projections are at least partially supported:

Stereographic Projection:  (1)
Orthographic Projection:   (2)
Lambert Conformal Conic:   (3)
Lambert Equal Area Conic:  (4)
Gnomonic:                  (5)
Azimuthal Equidistant:     (6)
Cylindrical Equidistant:   (8)
Mercator:                  (9)
Aitoff:                   (12)


NOTE: Map projection support in GDL is a work in progress.  There are
BUGS!!  These will be fixed as time permits.  Additional projections
will also be added in the same manner.  Bug reports and projection
requests are appreciated.

Joel Gales


PS (by AC): a demo ("test_map.pro") is now available in the testsuite/.
This demo is fully working on x86_32. Last example does not
work now on x86_64 due to limit= keyword
