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sean3dmonkey
09-30-2009, 05:54 AM
I'm using mental ray with production quality and I get several black pixels in my render. Is there a check box i forgot to check?

I have attached an image.

Sean

phix314
09-30-2009, 07:03 AM
Strange. Rendering as .exr? I got black spots with the T2S shader rendering out 32bit floats. Turned out the values in those areas were too high for the shader to handle. Could be something similar.

playmesumch00ns
09-30-2009, 09:19 AM
Yup those are NaNs or +/-inf values. The little squares that you see will be the same size as your filter width, since the bad values generated will propogate to all pixels touched by the filter.

They're basically the result of bad shader code - either a divide by zero or an overflow. Short of diving into the code and trying to debug it, you might have some luck trying different values for your lights and shaders and hope you don't trip whatever bug is causing that.

lazzhar
09-30-2009, 11:26 AM
You could also try using this shader DL3DBlackspotsRemover :
http://www.dl3d.com/index.php/telechargement/telechargement-de-shaders.html

sean3dmonkey
09-30-2009, 05:25 PM
hmm. don't know much about the shader bug stuff. I'll try painting them out in the render.

thanks for the help fellas.


Sean

sean3dmonkey
09-30-2009, 05:35 PM
Come to think of it. The pixels are not on the object with the shader. The black pixels are on the light rays, the lights don't have a shader on it. Could there be a check mark box in a render tab or a light tab that I need to check or uncheck?

Sean

playmesumch00ns
09-30-2009, 05:42 PM
Sorry I don't know enough about mental ray to know precisely what's going on, but there'll likely be a volume shader somewhere that's running to create the light beams effect. Tweaking the volumetric settings might help.

Whatever you do file a bug report with autodesk or mi

phix314
09-30-2009, 06:09 PM
You could also try using this shader DL3DBlackspotsRemover :
http://www.dl3d.com/index.php/telechargement/telechargement-de-shaders.html

Possibly one of the most useless things I've downloaded. For me, at least. Unless they're very small or on an area of no detail, its still gonna be work to remove them in post. May as well figure out why that's happening to begin with.

lazzhar
09-30-2009, 08:03 PM
Possibly one of the most useless things I've downloaded....
You did? I never downloaded this as far as I remember because I never got those black spots.

sean3dmonkey
09-30-2009, 09:01 PM
Cool, where would find this volume shader?

Sean

sean3dmonkey
09-30-2009, 09:12 PM
Cool, so the black pixels went away when I broke the connection of the noise map tot eh Fog spread. I just gotta find a map to plug back in that doesn't give me black pixels.

Sean

kanooshka
09-30-2009, 09:59 PM
If that was the problem it's possible you were using a 2D procedural when a 3D was needed or vice versa =)

phix314
10-01-2009, 01:02 AM
You did? I never downloaded this as far as I remember because I never got those black spots.

Yea like I mentioned the T2S shader had some of that when it was used for glass coating, the blackspot remover simply "spot tones" those little fellers. Not very useful when there's a fair amount of detail around em.

sean3dmonkey
10-01-2009, 01:55 AM
Cool, thanks for all your help, guys.
Sean

lazzhar
10-04-2009, 02:46 PM
Another thing that could create black spots is shown in this example (http://community.livejournal.com/antimentalray/3139.html). It's showing some cracks on a nurbs sphere but I tryed wich polygons and subdvs and it has this problem as well.

sean3dmonkey
10-05-2009, 05:28 PM
Cool ,thanks for the heads ups. The black pixels that I had were coming from the low rez image I had plugged into my light. When I put in a 1024 map, the black pixels went away.

Sean

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