A translucency similar to the one in Corona material

[Midiaeffects]

This is something I miss since a long time in Vray. It's very simple, the effect is quite similar to a refraction with 0 roughness. Most renderers these days have such a feature, and as I understand, it's sort of a "lambertian refraction", or a fully diffuse transmission. It's usually very fast to render, and it's great for creating translucent materials without having to resort to Vray2Sided, like leaves or lampshades. And also works with solid objects which is a big plus alone. And, at least in Corona, it can be freely mixed with refraction and used with SSS (ScatterVolume), providing a wider range of possible effects.

To me it's must have feature...

Regards,
-Eugenio

[vlado]

It's somewhere on the "to do" list, however keep in mind that its effect is exactly equivalent to using a VRay2SidedMtl material.

Best regards,
Vlado

[LudvikKoutny]

It's somewhere on the "to do" list, however keep in mind that its effect is exactly equivalent to using a VRay2SidedMtl material.

Best regards,
Vlado

If it is exactly the same then do I take it that the problem of VRay2SidedMt incorrectly subtracting reflectivity with increasing translucency amount has been fixed? Because last time I checked, I still was not able to create significantly translucent materials that remained reasonably reflective.

Also, part of the request above was ability to propagate SSS through translucency (diffuse surface scattering combined with subsurface scattering). That one 2SidedMtl can't do either, as its translucency model completely ignores any volumetric media inside.

[LudvikKoutny]

Here's also practical example of the limitation: https://youtu.be/oZBZ-G-6rcw

Along with a real world example of typical material that is highly translucent but quite reflective at the same time.

[vlado]

We've been through this a hundred times, I don't intend to rehash the topic I've said pretty much everything I've wanted to say on the subject. [Also, of course you know that Corona's implementation does not represent exactly the behavior of real-world materials either, so it's somewhat useless as a reference. Ideally you'd want to use a more exact physical measurement of the material properties, or a VRScans material to compare.]

Best regards,
Vlado

[LudvikKoutny]

Well, of course if I wanted to get perfect results, I could just model the 0.01mm thick plastic sheet and apply real SSS material on it, or use VRScans, as you said. My point is only that while neither 2SidedMTL nor CoronaMTL are 100% accurate, I do believe Corona's approach is more accurate then V-Rays. It just comes down to me needing to create pretty looking image, of foliage for example, and having hard time to do so, because activating translucency steals from the reflectivity of my leaves and they just don't look as close to the photo references anymore. Last time I checked VRScans, there were not many leaf materials to shade trees with

That being said, knowing that it's on the TODO list is enough for me. At least I will get my, equally as wrong method, which I will be happy with

[Rens]

For now you can always layer the reflection on top as a separate material so it stays intact.

[Midiaeffects]

It's somewhere on the "to do" list, however keep in mind that its effect is exactly equivalent to using a VRay2SidedMtl material.

Best regards,
Vlado

Okay, now you forced me to really think about it so I had a more in depth look into this. But I'm sorry Vlado, you're right! ...I'm feeling stupid now, never thought 2Sided as a kind of "lambertian refraction", but now makes total sense though.

What was really surprising is that using a Vray2Sided as coat on top of a VrayBlendMtl with a VolumeScatter as the base, works like a charm! It also works with refraction, though things get tricky since layer order matters and I don't have Corona or FStorm now to play with and compare. I suppose it's VolumeScatter as the base, 2Sided next, then Refraction, then Reflection.

But in the end I guess my request makes even more sense now. It would make things sooo much simpler/faster to setup. With a translucency amount and a color slot parameters on VrayMtl, you are cutting loads of steps and confusion to do the same thing. I hope to see this feature in VrayMtl soon.

Regards,
-Eugenio

[algato]

Hello Vlado,

I miss a translucency similar to the one in Corona quite vigorously. Whether the solution is 100% physically correct or not is in my opinion not that absolute important. Simplification of the solution reduces the processing time and, above all, unifies the solution. It reduces the source of errors when freelancers or employees are developing their own strange VrayBlend stacks and you're only then checking and wondering why the scene gets the "last buckets taking forever" or cosmic render times.

Kind regards
Alex

[Midiaeffects]

Looks like this topic don't want to die .

Because of this topic here on the forums about a leaf shader, I played a bit more with Vray2Sided. When I played with Vray2Sided and Cycles Translucent BSDF both looked exactly the same as Vlado stated. But my test was kinda loose, should have been me more methodical.

This time I was a bit more careful on the tests. I turned GI off and changed the front/back colors to Green/Red respectively. Now the difference became quite apparent. While Vray2Sided simply swaps shading from one side to the other, as we can clearly see with 0% and 100% translucency; VrayMtl with Translucency + 2Sided properly reveals backface color with the amount of lighting falling on the surface.

What I could never expect is that using VrayMtl *with* translucency inside a Vray2SidedMtl would change both materials behavior. While in the VrayMtl you set the color of the translucency, the amount is controlled by the translucency color in the Vray2SidedMtl. Totally counter intuitive, though very simple to setup.

Regards,
-Eugenio