volume vs volumetric geomtry and cryptomattes

[LeoYfver]

Hello!

I want to use cryptomattes on mistboxes we use so that compositors could control them individually. I tried switching to "volumetric geometry" but it has a lot of issues with intersections as in the example attached, it also has stepping issues. Is this a general issue with volumetric geometry and is there a possibility to get cryptomattes to work with "volumetric"

Regars Alexis

https://drive.google.com/file/d/1UrU...ew?usp=sharing

[Gosho.Genchev]

Hey Alexis,

I've pinged the dev team for the Cryptomatte support in Volumetric mode.

Regarding the artifacts for the intersecting volumes - could you please check if using the Multi-Matte element is an option ? It seems to produce a much cleaner result on my end. I understand that it's less flexible and I'll see if something can be done about the Cryptomatte element but it appears the issue is present across all integrations so I can't promise you a quick fix here.

Best regards!

[LeoYfver]

Indeed the multi-matte looks a lot better! Because of the intersection artifacts we still need to stay with volumetric where neither multimatte or cryptomattes work.

Thanks for answering and checking up on the issue!

[LeoYfver]

Hello again! We really want to start using both cryptomattes and deep for our volumes but unfortunately the "volumetric geometry" is unusable for us. They are supposed to yield the same beauty but so far it never has for me and the "volumetric geometry" results are not close to the desired look or how the vdbs looks in other renderers.

Is there a possibility to make the volumetric being able to create deep and cryptomattes?

In the image the left is "volumetric geometry" and to the right is "volumetric", no other changes are made to the shader or rendersettings.


Regards Alexis

[georgi.zhekov]

Hey,

Does increasing the Max Transparency Levels in the V-Ray settings help?
The scattering will look different as Approximate and Approximate+Shadows options for the Scattering parameter in the Smoke color window are not supported in Volumetric Geometry mode, but the overall look should be the same.

Cheers,

[LeoYfver]

it did help alot actaully but its still incorrect and we also have problems with intersecting volumes as the first example i added here.

in the examples below you can see that even with 1000 in transparency levels and 0.000001 in transparency cutoff, its still cuts off the thinnest part. with the volumetric and the mantra you can see they render the same(except ofcourse the brightness). and it goes without saying that it took forever to render the volumetric geometry one

[georgi.zhekov]

Ah, sometimes 1000 might not be enough when having thin parts, so you might need to bump the transparency levels to 2000-3000 or may be even more. Unfortunately this will increase the render times indeed.
We have not forgotten about the support for Volumetric mode, it's definitely in the to do list, though I can't give an exact estimate when it will be ready.

[LeoYfver]

thats good to hear Im really waiting for that one

just to add i tried with 10 000 in transparency levels and i get the same cutoff on the density, the alpha seems to be the same though