Translucency (thin walled SSS) element

[brunonz]

Hi.

Can we have translucency element added to the list of render elements? To control the amount of translucency in post production?
SInce vray aproach to translucency changed to thin walled SSS, it would be nice to have it separate and maybe add a vray 2 sided material element as well, for old scenes.

Tks!

[3DZver]

Hi.

Can we have translucency element added to the list of render elements? To control the amount of translucency in post production?
SInce vray aproach to translucency changed to thin walled SSS, it would be nice to have it separate and maybe add a vray 2 sided material element as well, for old scenes.

Tks!

I join brunonz. It would be very nice if there is a render element "VRayTranslucency" as in Corona "CESSENTIAL_Translucency".

[Joelaff]

Would be nice.

You may be able to achieve something similar by putting your translucency map into a VrayExtraTex and combining that with light select passed in post.

[^Lele^]

I join brunonz. It would be very nice if there is a render element "VRayTranslucency" as in Corona "CESSENTIAL_Translucency".

Could you show me an example comp where that RE is used, and how?

[3DZver]

Could you show me an example comp where that RE is used, and how?

Hello, Lele. Unfortunately, I can't show it now because I'm far away from my work computer (I'm on vacation ). But half a year ago, in one of the projects that I did in Corona, when post-processing the final image, I needed to adjust the strength and color of translucency in window blinds and on the leaves of houseplants, for which I used the CESSENTIAL_Translucency render element. It would be nice to have a similar render element for such purposes also in V-Ray for the VRay2SidedMtl material and for the VRayMtl material with "Thin-walled" and "Translucency>SSS".

[Joelaff]

Extremely useful for when the client says, “Looks great, but I want the levers to glow more from back lighting.” With the element you wouldn’t have to re-render, but could make a simple comp tweak instead.

[^Lele^]

Hello, Lele. Unfortunately, I can't show it now because I'm far away from my work computer (I'm on vacation ). But half a year ago, in one of the projects that I did in Corona, when post-processing the final image, I needed to adjust the strength and color of translucency in window blinds and on the leaves of houseplants, for which I used the CESSENTIAL_Translucency render element. It would be nice to have a similar render element for such purposes also in V-Ray for the VRay2SidedMtl material and for the VRayMtl material with "Thin-walled" and "Translucency>SSS".

That needs no specific translucency RE, it's a simple materialselect RE with us, or through an LPE if one wanted the finest of controls.
My question was precisely to figure out how on earth could one post-change translucency (f.e., the color of either side, or the fraction) and that's not on the cards, as i assumed.
We'll see what -if anything- could be done about it, but the shading pipelines between the two products couldn't be more different, so don't assume it's a possibility for us in the same way it is for Corona.

[brunonz]

That needs no specific translucency RE, it's a simple materialselect RE with us, or through an LPE if one wanted the finest of controls.
My question was precisely to figure out how on earth could one post-change translucency (f.e., the color of either side, or the fraction) and that's not on the cards, as i assumed.
We'll see what -if anything- could be done about it, but the shading pipelines between the two products couldn't be more different, so don't assume it's a possibility for us in the same way it is for Corona.

Not only for post production a translucency/thin walled could be useful. It can be used to check which materials have or check which is working. Sometimes i have to dig deep onto materials to see if translucency is working.

On vray, to have a similar element, i set some vray lights with include only vegetation objects. But the result is not 100%, but is a workaround.

Maybe Corona and Vray has different ways of calculations, but i believe there´s must some way to make it work.

Appreciate all the info.

[algato]

Hello Lele,
thanks very much for your contributions regarding the translucency/thiin walled render element.

I am not successful in build up a proper LPE formula.
Could you please post here, how such a LPE formula should look like ?

Thank you very much
Kind regards

[^Lele^]

Hello Lele,
thanks very much for your contributions regarding the translucency/thiin walled render element.

I am not successful in build up a proper LPE formula.
Could you please post here, how such a LPE formula should look like ?

Thank you very much
Kind regards

Sure, here:

to select all the SSS events in the scene

C<TD>.+L

to select the SSS contribution just from the material named "Material #1"

C<TD>.'mMaterial #1'+L

documentation
LPE builder

Notice the LPE is parsed at least for some errors, and the log may contain clues as to what isn't working.

[algato]

Hello Lele,

Thank you for the support and the great input.

Kind regards
algato

[algato]

Hello Lele,
unfortunately this formula does not capture the content of thin walled translucency sss (tree leaves illuminated from behind).
It is not about the classic sss like wax or marble block.

Is there a special formula for thin walled translucency sss?

Kind regards
algato

[^Lele^]

You are very right, it only supports normal SSS, the second "thin-walled" is turned on, the LPE comes out as black.
I'll raise it with the devs, see if it's fixable at all.

[algato]

Thanks for your effort
Kind regards
algato

[^Lele^]

It seems that when thin-walled is activated, the SSS ray is stored in the diffuse result (it does make some amount of sense. regardless, it's this way.).

Assuming the shader is called "TWSSS", this expression ought to capture its direct contribution:

C<RD'mTWSSS'>L

With another LPE you can also extract all the indirect contribution of the shader, using this expression:

C<RD'mTWSSS'>.L

Should you wish to have all the contribution of the shader, then this would work:

C<RD'mTWSSS'>.*

Thanks, as usual with LPEs, go to the most excellent Dian.