🚀 go-pugleaf

> I can't seem to get volume rendering to work correctly.  I've
> played with the splat sizes, adjusted the colormaps, prayed
> to the computer gods, but nothing works.  I've decided that
> I just don't have the hardware for it (low computer self image).
> 
> The problem is I get solid splats.  I can't seem to make them
> semi-opaque (sp?).
> 
> 
> I have a 4D35/TG and hinv gives me 
> 
> Graphics board: GR1.2 Bit-plane, Z-buffer, Turbo options installed
> 
> Do I need something else? or am I just an underachiever?
> 
> 
> Thanks for any help, or any recomendation of a good therapist that
> specilizes in computer caused mental disorders.

Gus,
	
The algorithm in VolumeToGeom uses alpha planes to make images
"semi-opaque". The rendering details of this algorithm can be
found in :

@article{DH91,
	author={D. Lear and P. Hanrahan},
	title={Hierarchical Splatting : A Progressive Refinement
		Algorithm for Volume Rendering},
	journal={Computer Graphics (SIGGRAPH '91 Proceedings)},
	volume={25},
	number={4},
	year={1991},
	pages={285-289}
}

If my memory serves me well, the TG does not have any alpha bitplanes.
Perhaps this should have been stated in the manual of VolumeToGeom or
cxGeoVolumeDefine.

All SGI models that support alpha planes should work. The base system
Indigo does it in software; others have alpha planes in hardware.
There is a neat program called 'ginv' which gives you a graphics inventory
of your machine.

-- Robert van Liere

PS.:  Why do you let these visualization packages drive you nuts ?
There are plenty of people on the net that are usually willing to
help. Just ask.
-- 
Robert van Liere, Department of Interactive Systems,
Center for Mathematics and Computer Science (CWI)
Kruislaan 413,  1098 SJ  Amsterdam,  The Netherlands
email: robertl@cwi.nl | tel: +31-20-592-4118 | fax: +31-20-592-4199