How does VrayMTL translucency work...?

[davision]

Tashko, the refraction glossiness problem is still there with 3.10.02.

I have added a scene file here. The only difference between the two figures is the one on the right has a lighter refraction color and translucency turned off. Otherwise this file is the same as the one posted by Svetlozar earlier on this thread.

translucency01 - file from Vray forum - rod added - refract gloss problem.zip

[svetlozar.draganov]

There are overlapping triangles in the scene (there is a plane that is exactly aligned to a VRayLight). Not sure why Svetlozar set the scene up this way; it's best to avoid overlapping faces.

Best regards,
Vlado

That plane was used as a reference geometry in Maya since Lights are not transferable and I wanted to have identical scene on both platforms Max and Maya.
It seems I have forgotten to remove it - I'll fix that and I'll update the attached scene.

[tashko.zashev]

Tashko, the refraction glossiness problem is still there with 3.10.02.

I have added a scene file here. The only difference between the two figures is the one on the right has a lighter refraction color and translucency turned off. Otherwise this file is the same as the one posted by Svetlozar earlier on this thread.

[ATTACH]22168[/ATTACH]

Hi,
Thank you for the file. It looks like a bug to me, but I have to discuss it first with our developers before sending a bug report.
The refraction IOR is somehow changed when the Glossy value is below 1 and Translucency is set to Hard model. For the other two models (soft and Hybrid) it works different.

[peterguthrie]

it would be great to have Svetlozar's explanation of translucency added to the chaosgroup help site, would that be possible?

(partly so i dont have to search for this thread every time i get stuck with translucency!)

[tashko.zashev]

it would be great to have Svetlozar's explanation of translucency added to the chaosgroup help site, would that be possible?

(partly so i dont have to search for this thread every time i get stuck with translucency!)

I think this is possible. Let me check first and I will get back to you later.

Update: Yes, we'll do it.

[Deflaminis]

it would be great to have Svetlozar's explanation of translucency added to the chaosgroup help site, would that be possible?

(partly so i dont have to search for this thread every time i get stuck with translucency!)

It's sort of reassuring that even the legends of this industry get stuck once in a while.... keep up the amazing work.

[peterguthrie]

me?? I'm on this forum every 5 minutes trying to remember how to do stuff!

[jpl1040]

Quick question... how does the Light Multiplier work? I've had it everywhere from 0 to 100000 and nothing seems to change. Just curious.

Thanks,

-Neal

[svetlozar.draganov]

Works as expected on the sample scenes attached into my previous posts:


Would it be possible to send us the scene for investigation?

[jstrob]

Also please hold in mind to use only gray scaled colors for Reflection and Fog colors - otherwise the result won't be expected.

I guess you meant: "Refraction and Fog Colors"...

[tashko.zashev]

I guess you meant: "Refraction and Fog Colors"...

Yes, exactly.

[ARTECONI-CGI]

Hi Svetlozar,

Thanks for the explanation , my reply arrives late.
Will you be able to easily reproduce the same conditions under the LWF? I see you're not using gamma correction and the sRGB button.
Personally I find easier to see translucency effects / light falloffs in a gamma 1 environment as you seems to be working.
The challenge comes from the fact that you're in a very high contrast situation that makes translucency easy to see. Black environment, 1 single light, gamma 1 and a refraction value of just 10 out of 256.
Will the effect be so obvious in a normal environment with linear workflow and GI bouncing around the subject as if it was in a lit room?

Regards,

Giacomo.

[svetlozar.draganov]

If you could provide a sample scene with the described setup I may try to make it work.

[sharktacos]

This would be a good thread to have pinned. Great info Svetlozar!

[svetlozar.draganov]

This would be a good thread to have pinned. Great info Svetlozar!

Thanks for the nice words