Compositing beauty pass with vrscans

[MANUEL_MOUSIOL]

This is more or less urgent.
I have the feeling that I have to redo all materials in my scene...

I want to composite everything together froms cratch in AE and I am using quite a lot of vrscans.
Now they dont turn up in the diffuse pass, which seems logical when thinking about it, but there has to be something can be done about this, so one can be flexible in production...

[Ivaylo Katev]

Wchich version, 3.6 or next?
Well, they have one important difference, but still both of them have no diffuce component, because the materials are not decomposed to diffuse+reflective idealised components.
In 3.6 all the secondary rays are considered "reflection" and are stored in the reflection element, in 4 the reflection element receives only the clear coat contribution, because that is really reflection and you can see the environment in it, all the rest indirect rays are stored in the GI element, even if no GI is enabled in the VRay control panel. In general, you have three major elements - direct light, indirect light (GI), reflection.
Can you describe the problem more precisely? The elements do not produce the original result or something else?

[MANUEL_MOUSIOL]

Using vnext.
Renderelements were black for diffuse and GlobalIllumination too for the vrscans, until I added all the lights in the vraulightselect element...
strange. I will try to composite it back to beauty and come back to you if something seems off.

[MANUEL_MOUSIOL]

Rendering out a single GI image from the framebuffer gives me the vrscans, but when rendering out multiple elements at the same time, GI is black. This also happens when automatically rendering out an animation.
I am rendering to 32bit EXRs.

[MANUEL_MOUSIOL]

sorry, my bad. I had two GI render elements in the list and strangely one was black and probably overrid the other one...

[Ivaylo Katev]

perhaps this must be not allowed then, but now with one GI element is everything ok?

[MANUEL_MOUSIOL]

I actually switched to full mode of the light select so that gives me a very close result to beauty.
Not sure about the right process of comping back to beauty though, if I wanted even more control. The docs are a little sketchy and don't refer to after effects .

[Ivaylo Katev]

there are two "official" graphs for compositing that should return 100% the original final result
https://docs.chaosgroup.com/display/...+%7C+RGB_Color

[MANUEL_MOUSIOL]

Does + mean add mode and x multiply?

[Ivaylo Katev]

yep, x is multiply, + is add

[MANUEL_MOUSIOL]

coming back to this topic, as I need to be able to be flexible for this new project.
I want to be able to tweak the carpaint color in post. So I need the diffuse element and then comp reflections etc on top.
so what I did was to output via lightselect a render pass for diffuse, specular, indirect diffuse, indirect specular. comping that brings me CLOSE to the beauty pass, BUT beauty is at places a little bit brighter, as if something is missing in the comp. can this be achieved? what am I missing?
using the latest official vnext version btw

[Ivaylo Katev]

Perhaps the reflection of the clear coat? Btw, few months ago we introduced a new render element that is dedicated exactly to make possible the color replacement in post. Your way is hard to use, i mean ok, let say you are able to restore the beuty exactly as it is, but the "diffuse" color is not uniform, there are flakes, there are small changes in the saturation depending on the angle, and if you replace this layer with the new desired color in uniform way, the paint behavior will be changed. As you know the vrscans have an option to replaces only the target color preserving the color variations and thus the material behavior (see the appearance panel). Now there is a render element that makes possible to implement the same color replacement algo in post, the elemnt is called something like "vrscans paint mask", see the attached graph that shows how to use it. https://www.dropbox.com/s/ted8zltfw2..._paint.nk?dl=0
Note that the graph requires the "original color" of the material. You can obtain it rendering a plane in pure white environment and averaging the result.

[MANUEL_MOUSIOL]

Note that the graph requires the "original color" of the material. You can obtain it rendering a plane in pure white environment and averaging the result.

I dont get that part.
I am working in 3ds max btw. Is there any difference?
I am a little afraid to change to the nightlies now just before big production too..
I think I know what you are getting at about the difficulty changing diffuse in post the way I tried. I think it would be alright, with some hue changes and some curves. It wont be the biggest color change of all times.
But maybe you can tell me about the new method a little bit, please?
I have to render with CPU and I generally found CPU engine more stable. I still have a few days before production starts, so maybe I will swithc...but, AH! I have to render on rebus or so...they wont have the nightly... Trouble, trouble.

[Ivaylo Katev]

well, the above described method requires nightly build, so if you are in the middle of production it's better to use official one, can you post the images where the difference appears?