strange reflections (stains) on vray glass material

[HAL-E]

Does anybody know where these strange stains on my glass come from?

the model should be fine, as well as the material settings (refl. / refr. glossiness = 1, fresnel ior 1.6, max depth 10, options: reflect on backside)

scene rendered with hdri (vray dome light)

rendersettings: no reflective gi caustics, 1.bounces irr map. 2.bounces brute force, dmc sampler: adaptive amount: 0.85, noise threshold: 0.002, min samples: 8

 

thanks for any help!

[Thablanch]

I know you said the model is fine, but can you still show a wireframe screenshoot.... Really looks like a model issue

[HAL-E]

Ok, here's some screenshots of the model. It's an editable poly, all the vertices are weld...

[Joseph Petrino]

It might be a coplaner face issue.

 

Try upping your "Secondary rays bias" setting a bit.

[HAL-E]

I just enhanced the secondary rays bias but the rendering still looks the same.

[Craig Ramsay]

In your glass material, what is the max depth set to for refraction? You'll probably want to go higher than the default setting of 5 for that model.

[HAL-E]

Thanks for your suggestions. My glass material has a refraction max depth of 10. But now i found out that it was a smoothing group issue (look at the attachments). In my opinion, smoothing group angle 10 looks best.

 

cheers!