RGB lights and adjusting lighting in composite

[jensl]

I often use RGB light passes (example attached) as a sort of normal-pass for the beauty lighting. This allows fine-tuning and intensity shift to be handled in compositing. I wanted to see if other people have faster methods, or if this is something that could potentially be a render element.

Since all of the lights are being calculated, I wonder if it would be possible to kick out lights (or light sets) separately from the framebuffer, like multiple 'lighting' render elements. This would be amazing as it would be 'free,' compared to rendering a custom layer or multiple beauty versions.The method I usually use is to copy the beauty shading, override lights into R, G, and B, and assign a fully diffuse white V-RayMtl (if reflection is minimal and the diffuse lighting is what needs adjusting). Anyone have different / better methods, or could this be done in the framebuffer? Thanks.

[shadevfx]

you could probably achieve similar results with normals and point passes and a relight tool in comp..

just a thought

[ultrasonic]

I would rather have an option to output the renderelements per light. In houdini u have a very simple option that does this trick.
I could imagine that all lights get rendered in the standard buffers and that the lights you choose to be in seperate buffers will render to "diffuse_lightname" , "refl_lightname" and so on...then u only need a checkbox in the ligths where u can specify if this light should get its own buffers.
@vlado & vladimir: what do you think about it?
cheers
Oli

[ultrasonic]

you could probably achieve similar results with normals and point passes and a relight tool in comp..

But then you lack shadows or do you have a way to work around this?

[jensl]

Shadevfx - I would love to get a point/normal/relight setup, as I know this has been done for Nuke but it doesn't seem like it's available out of the box for Nuke and V-Ray. We often use AE for compositing, and I think that's even farther from a relight setup. I was very impressed by The Foundry videos on District 9, though.

Oli - That sounds like just what I am looking for. This seems to be called lighting contribution buffers or pass contribution maps in MR. This would be very powerful if I'm correct in my understanding that this could be done with minimal increase in render time.

[Morbid Angel]

i asked for rgb lighting intergration via light id for years. Hopefully some day we will see it.

[Hoegaard]

Indispensable tool in Houdini. I'll be sad to not have separate lighting output channels per light in Vray.

[vlado]

We can only separate the direct lighting contribution from a given light source (this is a planned feature anyways), but not its indirect contribution for GI.

Best regards,
Vlado

[ultrasonic]

but not its indirect contribution for GI

Not even with "brute force" for both indirect options?

[vlado]

It depends; it can be done in principle, but there might be some performance hit. I won't really know until I try

Best regards,
Vlado

[jensl]

Dmitry I'm glad you're way ahead of me and put in a request long ago.

It'd be useful to have this feature even without indirect compatibility. But it would be great if that worked eventually.

[olivervfx]

mm would be handy if it could be done with "gi contribution"

cause then you'd have a lot of control, and you could link the 2 in comp.

(direct and indirect)

Can't wait till this option exists.

[jasonhuang1115]

Hi,

Just found this thread when searching for the same solution in Vray. We really need a feature where we can extract the full contribution (Beauty pass) or partial contribution (direct, spec, reflection) of each light for tweaking in post. The current Light_Select_RE is a good starting point, but I found that the reflection of lights cannot be extracted on a per-light basis (correct me if I got it wrong).

The default light contribution map feature in Maya is great, but its implementation to MR is not complete, either (not support the majority of MR shaders).

Thanks,
Jason