miSSS Back Scattering Broken in Scene

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  11 November 2012
miSSS Back Scattering Broken in Scene

Hi All,

I have a interior artery(referenced) scene with misss x passes shader. It includes three other referenced objects (Red, White, Platelet Cells) with misss x passes(instanced to nParticles). The back scatter works in ref files, but not in scene file. I'm questioning the light maps... Each referenced object has its own uniquely named light map and mentalrayTexture. Is this what is breaking the back scattering, possible? Do they each need their own light map, being a reference in a scene? Is there a way to use only a single light map for all referenced objects?

Artery reference file render:

Artery referenced in Scene file(back scatter not working):

Artery SSS settings screen shot:

  11 November 2012
When I've used SSS, all my materials use the same light map. I've had problems too when importing objects with SSS shaders, and the problem was something with the lightmaps. What I did was delete all the lightmaps that were already on the materials, then create a new default SSS, which automatically creates a lightmap. I then connected that lightmap to all the other materials and everything worked fine.

Last edited by newguy4life : 11 November 2012 at 08:24 PM.
  11 November 2012
Thanks for your response. I assigned all the SSS shaders the same light map. That fixed all the cells back scatter. However I'm still not getting any back scatter on the artery wall like in the original reference file. I'm thinking now it might have something to do with making it a collider nRigid for the cells to bounce off of. Will keep digging. Any suggestions still welcome

I have light linking on:

Artery Back pointLight (should "glow" through the bend in the wall) = lights everything
Artery Front pointLight = lights only Artery
Cells Back pointLight = lights Cells only
Cells Front pointLight = light Cells only

  11 November 2012
Hmm, you could just hide the one you made a rigid body, and duplicate it to take off all the nCloth or whatever is on it, then apply the material to the new one. Maybe that will work.
Demo Reel 2012-13!
  11 November 2012
I've had issues using one light map for the whole scene. Stuff doesn't light up right, similar to those images above.

I just use multiple lightmaps which possibly increases render times, but you can offset that by cutting the lightmap resolution in half or even less sometimes as long as you don't have any really thin objects.

Last edited by sentry66 : 11 November 2012 at 09:37 PM.
  12 December 2012
Found the problem, solution maybe

The problem was with the camera scale. I scaled the camera down to fit inside the artery. I started rendering in perspective to troubleshoot, and the back scatter was working, Camera no dice. I dropped the Scale Conversion in the shader way down to .001 and the back scatter showed up in the camera, however it was very very grainy. I'm going to tweak the shader settings a bit and see if I can get something that way. If not, I might have to rescale all my objects and rerun the dynamics sim. So, to sum up if your having back scatter problems try rendering from the perspective view, check your scale on objects, camera, shader settings. Hope this helps someone else out.
  12 December 2012
Ah, that's good to know. I've had problems with other things when I scaled the camera, such as depth of field. Makes sense that it would affect SSS too, guess the moral of the story is never scale your camera.
Demo Reel 2012-13!
  12 December 2012
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