alsurface unwanted tinting and darkening

[Angus Hume]

I have issues where objects are next to each other. See the attached where the band around the lid has a strange darkening at the edges, if I increase the SSS radius to 10mm it gets way more obvious. The other issue is if I add say a warm colour to the SSS for the white material where the lettering is in the middle looks good but the colour at the edges of the band is darker and inverse colour. The lid is one material and the band is a second. All separate meshes.

[Angus Hume]

I got somewhere with the darkening on the band. Looking at docs for other DCCs I noticed that at least in Vray 5 there is an option for Consider all objects. On a hunch I looked in the channels and found "vray_consider_all_objects" set to false. I changed this to true. Seems to work better now.

[boyan]

Hey,Angus,

Happy New year!

Thank you for the effort and reports. Please check the V-RAy Mtl Option -> Rounded Edges Width -> Mode: Concave only.

Cheers,

[1funk]

If you set a rounded edge width, you will see the "consider same objects only" option appear under it

If you dont have rounded edges enabled, Im not sure why the setting makes any difference though.

[vladimir.nedev]

Angus is talking about a different option - "Consider All Objects", which is specific to the alSurface and Fast SSS 2 materials.
I think it's relatively new, that's why it's missing from the UI.
I will probably add it for V-Ray 5.

Greetings,
Vladimir Nedev

[1funk]

Ah yeah I see it in the channels list on nightlies only.

[Angus Hume]

Yes exactly. Nothing to do with the round edge shader. Modo SSS has had this option for ages. I read it recently in these docs for Arnold and so went looking in the channels in Modo just in case it was there but not in the GUI.

[boyan]

Hey, Angus, are you sure that the "Concave only" option did not fix the dark edges in your bottle? If you can add 0.0001 rounded edges the option will appear without interfering with the geometry.

[Angus Hume]

I'm unclear why the round edge shader has anything to do with alsurface darkening in vicinity to other similar materials? Both shaders already had round edge shader enabled for both concave and convex and I have just now tried it on concave only but that makes no difference I can see. The fix I found outlined above was to enable consider all objects for both the alsurface materials directly in the channels list. The round edge shader option in the channel list is a completely separate thing.

[Robert]

The alsurface will be obsolete in V-Ray 5.0 I guess. I liked it, but it was always a bit buggy. There is on bug that I run into, where the reflection went wrong, as the GI sampling of the reflect geometry always took the lower roughness value of the material. Thats why I switched back to the good old shader tree method of layering shaders manual. Works perfect.

[boyan]

Interesting, Robert could please share with me the workflow of this material, lighting setup and GI settings if possible!

[Robert]

Well I think you or vlado discussed that with me 3 years ago. I guess I used irradiance cache at that time. Do not use it anymore. I think if I remember the problem was only happening with IC,

[boyan]

Ok, thx for the details! In my opinion, We need to hide the IC from the GI menu option or at least to recommend avoiding it in fresh scenes.

[Angus Hume]

The alsurface will be obsolete in V-Ray 5.0 I guess. I liked it, but it was always a bit buggy. There is on bug that I run into, where the reflection went wrong, as the GI sampling of the reflect geometry always took the lower roughness value of the material. Thats why I switched back to the good old shader tree method of layering shaders manual. Works perfect.

Yes, if we ever see 5. I like the shader too, but they never finished the full implementation which was very frustrating. So Modo Vray only ever got half the shader functionality.