View Full Version : black spots in MR render (miSSSphysical)

09 September 2004, 08:27 AM
I encountered this strange problem yesterday. I was working with the new miSSSphysical material from mental ray on Maya 6. Rendering with one point light internal to the glass vase, using approx 1000000 gi photons plus final gather and it gives me this image with whole sections unrendered (I assume). Black spots everywhere!

I had great sucess earlier with the misssphysical node and dont suspect that is the problem. Things became an issue when I threw final gather into the mix. I am relatively inexperienced in using mental ray, so anyones thoughts would be greatly appreciated. Thanks.

09 September 2004, 01:42 PM
just throwin it in the air here but it could be the number of reflections in your shader needs increasing as well as the ones in the render globals. I've had similar problems too in the past with other shaders and thats what I had to do to get it working.

09 September 2004, 08:57 AM
Oh god, I'm glad someone else has this problem. This has been plaguing me for days, and it is definitely Final Gather related... I thought it was reflection-related, too, and still do, but I can't fix it by increasing the reflection number...

Sometimes, I can go back, and spot-render the bad portion, and it'll render correctly, but not always. I'm looking for a clue here, as well!


09 September 2004, 02:32 PM
I have had this problem a lot when using FG. Check out this thread:

It seems like different people find different ways of getting rid of these black spots. For me, I think I narrowed it down to a Maya area light in my scene that mental ray did not like. When I removed the area light, the spots went away. You may also have to rebuild your lights to clear out any corruption.

Good luck.

02 February 2005, 03:19 PM
ladies and gentlemen, i do have the solution to these ugly black dots.
its simple...
its maya 6.5 with mental ray 3.4!!!:bounce:

i also had black dots appearing randomly in the shadow rays of imported objects, but also when a transparent (your problem) objects was set into the scene.

i did a test rendering with one of my interior scenes and new maya perfectly works.

so hang on a few days and wait for maya 6.5.

what you can try elseway is rendering little buckets. often helped me out.
good luck!


02 February 2005, 03:50 PM
Those are invalid pixels. In Maya 6.01, there are some combinations of shaders that will break MR.

05 May 2005, 01:57 AM
6.5 + 3.4 ? not quite yet mentalimages :(

06 June 2005, 02:12 PM
So please welcome a new member of "blackspots" Mental Ray club....

Is there any real solution for that problem....Sometimes those spots appear sometimes they don't...
I'm posting an image whish was set up for rendered with MAYA SRenderer then i started to plug
MR shaders into existing Shading groups for rendering with MR...
The scene is not balanced in terms of lighting because as i know MR shaders are obviously more friendly with MR than default ones which unrealistically get illuminated by environment color...

Once again is there are any blackspot eliminator out there? :)

06 June 2005, 02:56 PM
I had the same thing some time ago. Never before I had the problem.
I did not find a solution, but I manged to find out what caused it.

I had two area lights in my scene. One of the 2 was causing the problem. The only thing that worked was removing that area light or switch of the raytrace shadow of one of the 2 lights.
The strange thing was that when i turned on ray trace shadows for both light, i got these nasty spots. When only one of the two area lights was casting shadow the spots were gone.

I used 2 area lights before and it was no problem. Replacing them by new ones did not work as well.

06 June 2005, 03:51 PM
The problem solved but who knows for how long...

I had a number of lights in the scene.....I set them all off except of one shadowcasting spotlight....and that solved the problem...
I dont think though that it was a raytracing issue because i m not using that "much" raytracing ... I have DM shadow maps and FG....

Anyway thanxs for instance reply ....

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