Transparency in GRASS rasters

[William Hudspeth]

Hello,


I am having a little problem with getting null(no data) areas in a GRASS
raster to appear as transparent in my mapserver client. In fact, I am
displaying one of two different GRASS rasters, both possessing null(no
data) areas over oceans. One of the rasters works just fine, allowing
one to view the bathymetry through the transparent areas, while the
other is quite opaque. As far as I can tell, both rasters have data
ranges of 0-255, and have null(nodata) values over ocean areas when I
use d.what.rast. You can view the effect at


http://falstaff.unm.edu/cgi-bin/reason/raster_processing_client.py


Under the Background Raster Layers dropdown, select the shaded relief to
compare to the default background when the page opens.


Any ideas on why one works and the other doesn't would be greatly
appreciated.


Bill.