many thanks Gustavo!! that was it.
2014-03-20 8:15 GMT-03:00 adrian wyer <[email protected]>: > Gustavo is correct, crank your Mesh Splitting Factor in the MR options > to something high, problem solved > > > > a > > > ------------------------------ > > *From:* [email protected] [mailto: > [email protected]] *On Behalf Of *Ola Madsen > *Sent:* 20 March 2014 08:11 > *To:* [email protected] > > *Subject:* RE: Mental ray volumetric shader errors > > > > I don't think that worked in my scenario as I had numerous overlapping > objects (was doing an x-ray shot) and I got the artifacts in the overlaps > as well. Though this was easily fixed by splitting the scene in a couple > of passes. > > > > o > > > > *From:* [email protected] [mailto: > [email protected]] *On Behalf Of *Gustavo Eggert > Boehs > *Sent:* Thursday, March 20, 2014 12:44 AM > *To:* SI mailing list > *Subject:* RE: Mental ray volumetric shader errors > > > > Hey Fabricio, i'be bumped onto that also, in my case it was the Mesh > Splitting kicking in. It separates dense meshes into separate objects > before passing them on to MR. Therefore, some shaders get artifacts, like > volumetrics and bumpmapping also. > > Real headache but easy fix... > > Under MR > Optimizations, look for Mesh Splitting Factor, increase the > value up to infinity and be happy :D > > Em 19/03/2014 19:20, "Ola Madsen" <[email protected]> escreveu: > > 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]>: > > 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: > > > > [image: Imagem inline 1] > > > > > > 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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