View Full Version : SSS (?) problem, dark shadowy artefacts and specs

06 June 2010, 07:01 PM
Hello cgtalkers;

a picture is worth a thousand words, so here are 3000words:

A few things:

I only have SSS (fask skins) with maps in it, increasing the lightmap rez doesn't do much (512), I have a 3 point lights, FG on (doesn't change whether it's on or off)

I also have an MR Proxy on the character.

removing the filtering on texture maps seems to do the job, but unfortunately this isn't very acceptable.

Ideas, anyone ?

Thanks! Sorry I can't post the scene.


06 June 2010, 10:12 PM
What happens if you change the lights?

06 June 2010, 03:41 PM
Nothing, I hid them one by one, changed spotlights. Does not work.

My mentalray tutor told be it might have to do with non-closed geometry; unfortunately this is post-animation and apparently maya doesn't like 'fill hole' on skinned geom.

The weird spec problem seems to have gone now I use mip-map elliptical filtering.

06 June 2010, 04:52 PM
You could duplicate the geo. Make the changes to it it. Smooth bind the new mesh to the old rig. Click on old mesh, shift click in the new mesh and do a edit smooth skin>mirror skin weights (options) and turn on Mirror Across (YZ). This will transfer your weighting to the new mesh... you can then delete your old mesh.

As far as an SSS solution.. not too sure.. but if that filter type is working and your not noticing any difference in rendering then ... maybe go for it?

06 June 2010, 11:31 AM
Well, the problem goes away on different machines, but comes back at other time, it's got me really confused, nothing seems to remove the probleme completely (filling in holes, changing the lightmap attributes, switching between spot/area lights)...

Anyhow, here's a new picture to show the problem (on a frame that used to be fine):

06 June 2010, 12:48 PM
I can reproduce similar artifacts that you are getting in that freaky looking dude in the last picture by using mip-map/elipticalFiltering while using a frameBuffer gamma that is not set to 1. It seems to occur more when parts of the mesh extend beyond the camera near clipping plane.
Try a render with frameBuffer gamma = 1 and see if the artifacts persist.

If its not that, then I'm not sure.


06 June 2010, 03:47 PM
is this with ray traced or shadow-mapped shadows?

also, sounds crazy, but I've seen texture coordinates somehow get weird and do this. What happens if you apply a regular planar or spherical projection and rerender?

06 June 2010, 09:51 PM
Solved! Apparently SSS does not like the new built-in shake cam attributes!

I'm kind of ashamed of not having checked this before, but I had an expression in the camera shake (which was introduced in 2009/2010 if I'm not mistaken) which simply does not compute. I removed the camera shake and added a real translate/rotate shake.

Thank you for your help!

06 June 2010, 06:09 PM
Wow.. I don't think I would had ever thought of that. Very interesting find!

CGTalk Moderation
06 June 2010, 06:09 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.