Proxy with SSS and Glas Material renders incorrect

[Jon3D]

Hi,

Simple Scene: A Glass Object with Milk ( SSS ) Material inside renders not correct if I render it as proxy object. The Fog color seams not to working properly. It always appears much more green than it should.

Scene Files are attached.

kind regards

Jonathan

[matanov]

Keep the glass and the milk as separate proxies and it should be fine. You've merged them in one when exporting and that is messing up the refractive shader.

[Jon3D]

Thank you!

"You've merged them in one when exporting"
Yea actually I do this very often because that is what I like with proxy objects

Would you recommend to separate objects always as separate proxys or only when working with refractive materials? Or is this some special case because of the SSS Material ?

kind regards

[matanov]

Would you recommend to separate objects always as separate proxys or only when working with refractive materials?

No, not always. Overlapping volumes with refractive materials may cause problems.

[hristo.dimitrov]

The issue you have is caused by the difference between the polygon ID's on proxy object and the mesh object.
On the proxy object they are in this order:
Outer and Inner polygons have ID 1 and the middle have ID 2
On the mesh object they are in this order:
Outer and Inner polygons have ID 2 and the middle have ID 1

And with material like this used in your scene you get different results.

[Jon3D]

What exactly do you mean with outer and inner polygons. Are you talking about surface/material IDs? I have only two material ID?s in the scene and i dont change them after I export the proxy object. So the surface ids shouldn?t change after exporting the proxy objects?!

Also if you compare the proxy with original mesh you can see the IDs are the same!

[hristo.dimitrov]

I mean that the object has 3 layers of polygons.
I imported the torus from the proxy object and compare it to the other in the scene and IDs was not the same.
I'm not sure why they IDs are changed after exporting. I will make some tests to investigate the issue.

[Jon3D]

I also checked that. If I extract the mesh again from the proxy all the IDs are fine.

But I discovered now that it even renders wrong if I attach the original Mesh to one Object without to create a proxy at all. Than the error occurs.

So maybe this is the error that I cant have a single object with different refractive shaders? At least the fog value seems to mess up somehow.

kind regards

[hristo.dimitrov]

It seems that VRayFastSSS2 causing the issue we are considering this as a bug for now as a workaround you can keep the object separately or use different material instead of VRayFastSSS2 like VRayScatterVolume or VRayALSurfaceMtl.

[Art48]

I remember some issues with SSS and/or refraction in relation to materialIDs and not seperate objects. Don't know what exactly it was back then, maybe it is fixed now, but it may be the same issue and may not have to do with proxies.