strange patterns in iray render

SF-Design

Hi there, I am having a problem I never had before. I am using some iray silk shader presets. But when rendering I get a visible pattern (checkers) on the surface of the object. The used maps do not have those pattern and I am wondering where they are coming from. Maybe someone had a similar problem and knows how to solve it. Thanks

Richard Haseltine

Sounds like some kind of Moire pattern, the grain in the silk presumably interacting with some other regular pattern. It is also worth checking that you don't have two copies of the mesh loaded.

SF-Design

Hi Richard,

thanks for your reply. 

I have only one instance of the mesh loaded. It looks like this (attached).
There is nothing in the scene but the pillow. 


 

Richard Haseltine

I don't know then - it seems too regular to be Moire, the emsh itself could be double-sided I suppose; where is it from?

SF-Design

This is from a product named Modern Bed 2 here from the Daz store. But I get this effect even when using a simple cube with this shader preset. Its really strange. The image maps used by the preset are completely smooth and do not have this pattern.

Richard Haseltine

Where are the shader preset from?

SF-Design

They are from me, I am in the process of creating a pack. 

These are the shader settings I am using, and the diffuse map

I tried several different settings, removed the bump and normal map to see what happens. But always this checkers pattern. 

Richard Haseltine

300 for Topcoat IoR seems an odd vlaue. I'd also worry a little about the extreme values such as 0 Diffuse Roughness and 1 Glossiness.

SF-Design

Okay. I changed the values for those 3 to several different values but it did not change much unfortunately. The render with the black pillow is with IOR 1.5 and different values for the other 2 settings. The pattern is still there. 
The others are with the same settings like before but with different maps. 
Seems that only the dark colors have this problem, but I do not know why. 
On the green one you can see this pattern too, but not so intense like on the black one. On the yellow one you cannot see it. 

Maybe I just need to save the darker presets without image maps just using a color. 
It does look similar then and no pattern. So I guess it must have somthing to do with the maps. The last 2 images are without image maps in Base and Topcoat, just using a black color. 

Richard Haseltine

Sorry I couldn't be more helpful.

SF-Design

Richard Haseltine said:

Sorry I couldn't be more helpful.

No problem.
Thank you for your help Richard