Volume rendering demo

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Volume rendering demo

Unread postby ChrisR » Sun Aug 23, 2015 3:43 pm

Hello all-
I have created a very simple volume rendering demo - it includes both the source code (src folder) and compiled executables for OSX, Linux and IRIX (list folder, which also includes sample images):
To download everything you just press the "Download ZIP". If people find this useful it could be easily added to a tardist. Here are a couple SGI specific notes:

1.) You can compile this either to use 2D textures (the default) or 3D textures. The advantage of the 3D approach is the simpler code and it uses 1/3 the texture RAM. The disadvantage is that some hardware (e.g. the SGI O2) perform very poorly with 3D textures. This explains why SGI's VolRen performs poorly on the O2, while SGI's O2 demo (closed source?) vrp2dO2 performs pretty well. Since the O2 had vast amounts of texture RAM, this was a clever choice.

2.) The application allows the user to change the contrast, brightness, color scheme, etc. Right-clicking on the application brings a drop down menu with a 'Help' function that shows all the functions

3.) The 'random spin' animation also reveals the performance of the renderer. On a modern computer the limit is the screen refresh, but with the default (128x128x128 voxel) image my 250Mhz R10000 O2 hits about 1 fps.

4.) The first 3 columns below show program with the included sample images - the final image shows a modern ray caster (MRIcroGL) which requires programmable shaders.


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Re: Volume rendering demo

Unread postby foetz » Sun Aug 23, 2015 5:07 pm

nice thanks it looks neat. definitely smoething for the show-off stash if needed :D

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Re: Volume rendering demo

Unread postby GL1zdA » Mon Aug 24, 2015 12:54 am

Thanks, volumetric rendering is always a nice way to show the graphics capabilities of a system. I've written a volume raycaster several years ago, but, as you have written, it used shaders so it wouldn't run on an SGI.
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