I can only confirm this nasty little bug as I experienced it a couple of years ago. If I remember correctly I managed to get rid of the artifacts on some objects by actually tessellating the geometry instead of using to + key. Some object still had the artifacts and I had to work around it by splitting the scene and rendering the objects in in different passes.
Cheers Ola From: [email protected] [mailto:[email protected]] On Behalf Of Fabricio Chamon Sent: Wednesday, March 19, 2014 11:05 PM To: [email protected] Subject: Re: Mental ray volumetric shader errors ...forgot to say that I'm using "Particle_Volume_Cloud", which used to work fine on meshes since always. 2014-03-19 18:56 GMT-03:00 Fabricio Chamon <[email protected] <mailto:[email protected]> >: Hi, I'm trying to do some volumetrics in mray, but the shader is giving me all kinds of wierdness on heavy meshes. Have anyone experienced this before ? For the sake of simplicity, I have this test scene with only one default sphere. If I crank up the sphere U/V subd to 200, it starts to show some strange black areas. At subd 300, it renders all flat. I'm guessing it's not a lookup table cell size problem...tried very small values, and the volume renders almost completely solid (when it works). here's some images to illustrate: I really need dense meshes because I want the fine control over the volume silhouette to be on the mesh itself, not through shader trees. anyone ?
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