3d views of elevation data

[Dan K Braithwaite]

I am trying to become familiar with the techniques of producing
3d shaded dem surfaces and could use some pointers.

After looking at the work of the USA CERL visualization group at
the www addr

http://baldrick.cecer.army.mil/grass/viz/global.html

I was very impressed by the small number of colors that were necessary
to highlight and define the terrain as well as a draped image of some
kind which looked a lot like the natural earth color data from one of
the global CDs but better.

The impression I got was that the images were created from the datasets on
the global grass CDs (I,II,II) using grass programs.  I have CDs I & II
and the global data is at best 5 min x 5 min and doesn't look near as nice 
when I try and display it using grass (d.rast) on my screen.

Are the grass scripts, blend, shade.clr, and shade.rel the tools I need to
take a dem and another data file for drape/color and produce an image similar
in quality to the amazon river basin gif:

http://baldrick.cecer.army.mil/grass/pics/amazon.rgb.gif

?

I am using grass4.1 on a SUN workstation. Hopefully, I don't need an SGI.

Any help/pointers would be greatly appreciated.

Thanks,

dan braithwaite
computer programmer
Dept. of Hydrology
University of Arizona
Ph: (602) 621-9944
Fax: (602) 621-1422
email: dank at hwr.arizona.edu