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View Full Version : Occlusion Plugin Bug and Workaround


gaushell
10-15-2004, 02:41 PM
I found a bug in Skidbladnir's Occlusion plugin that I thought I would share. I've been keeping him informed via email. Here is the actual plugin:
http://www.informatik.hu-berlin.de/~goetsch/AmbOcc/SG_AmbOcc_Exp.p (http://www.informatik.hu-berlin.de/%7Egoetsch/AmbOcc/SG_AmbOcc_Exp.p)

First - it is a great plugin! We are using it in production now for our interior animations and illustrations.

Here is the bug - which only occurs when using lwsn.exe (screamernet) on our renderfarm and never in layout (lightwave.exe). We use Butterflynet Render as the controller, but that is irrelevant as lwsn.exe does the rendering.

If you have a null object in your scene as the first object the occulsion plugin will not render properly - at all in fact.

The same scene works fine in layout, but for some reason doesn't when using the render nodes (lwsn.exe).

Now if you remove the null object and put it after the object(s) receiving the occlusion plugin then everything is fine.

At first I thought it had something to do with the Eki lighting rigs (Overcaster) for ambient light that we use, but it really was just that they were loaded prior to my interior objects.

I deleted the null and lighting rig and then reloaded it (thus placing it after the interior objects) and no problems now.

I successfully rendered 4 scenes overnight of several hundred frames without any problems. There are hundreds of polys and dozens of objects - no problems at all.

I tried a simple scene with one object and a null and had the same results. With or without shadows casting, receiving, etc. and with or without raytracing on. It is clearly the null being before the occluded objects.

So I recommend that everyone make sure they don't have a null as the first "object" in the scene for sure. The question is, can you have a null prior to a second object that is getting the occlusion plugin. I haven't had time to test that. Perhaps someone else can.

It seems to be an easy work around. Just wish it wouldn't have taken all day to figure it out - I was convinced it was the lighting, shadow settings or even something like fprime or multithreads - but it wasn't.

Thanks again Skidbladnir! This is a great plugin that adds some nice subtle "pop".

Regards,

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