...excuses.... the system has shrunk the image :( ... double click on it to see a larger version

Hi Folks,

I wonder if anyone can help out with explaining some Poser wierdness, and hopefully how to avoid it.

I have noticed that when I use Ambient Occlusion (AO) to get better shadows at skin-to-skin contacts, I sometimes get white lines appearing where the shadow should be darkest (like a dynamic range overload causing an inversion... or something like that).

In panel A of the picture is the kind of AO shadow I expect, but even here if you look closely (see panel B for magnification) you can see the beginings of the effect.
Panel C (a picture of gymnastic contortions :) ) shows that in some shadows the effect is there (red) and in others (green) it is not.
In some images this artifact is very strong, with a really white line running down the middle of a shadow.

I am using AO on the shaders (AO on lights switched off), using Occlusion Master (by face_off) and Unimesh Realism Kit (also by face_off).

Obviously this artifact is due to the lighting but I'm not sure what aspect of the lighting is causing it or how I can avoid it.
I use an IBL light and spotlights (usually a light set by R3DF).

If anyone can ... er... shed more light on this problem I would be grateful.

Thanks,

Isaac

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Come on you Poser Gurus... someone must have found a solution to this one...

I think jonthecelt wants to know too :)

I was able to replicate the problem in a scene that originally was ok by raising the Ray Bias in the material's AO node. Try running Occlusion Master again and lowering the ray bias value

Thanks nghaywood.... that appears to do the trick. Reducing Ray Bias from 0.4 to 0.1 seems to work, but I guess it will depend on many factors like how close I'm zoomed in, light intensity etc...
Still, now I know what to do when this particular Ugly raises it's head :)

Thanks,

Isaac