weird shadow rendering artifacts in Iray

tttiiimmm

In Octane, I learned that these kinds of things can be solved by changing the Ray Epsilon. But in Iray/DS no such setting exists.

Increasing the subdivisino will make this less visible, but it doesn't actually change the issue.

 

Anyone have a clue why this happens? I fuddled around the render settings, but nothing really happens.

tttiiimmm

nobody..? is this too uncommon an issue?

mjc1016

tttiiimmm said:

nobody..? is this too uncommon an issue?

Does it happen with a change in camera angle...like if you swing it around a little more so it's face on?

Other skin textures?

Lights?

 

Tobor

Do a Google search for iray shadow terminator artifact. It's a known issue, but not just with Iray. 

http://blog.irayrender.com/post/29042276644/shadow-acne-and-the-shadow-terminator

Hiro Protagonist

These artifacts will not uncommonly occur when the light hits curved smooth surfaces (like skin) at a tangental or "grazing" angle, for example side lights. Particularly, bright sharp lights such as sun and point lights or small mesh lights. There a few ways to fix the issue: change the angle of the light; increase mesh resolution on the model; use a more diffuse light. I think it's a problem with all ray-tracing, physically-based renderers.

mjc1016

Hiro Protagonist said:

I think it's a problem with all ray-tracing, physically-based renderers.

It's a combination of the way the meshes are made and the ray tracing...so yeah, they all are affected to some degree or another...with Iray being on the particularly finicky end of the scale.

jeff_someone

Do you happen to have a normal map applied incorrectly?  i.e., wrong map or dialed up too high?