comped render elements don't match RGB

[R_Cyph]

Hey,

We just upgrade to vray for maya 2.2 recently and I did a quick comp test. Unfortunately they don't match. There seems to be a problem with the diffuse and raw light passes. If I do a difference merge between comp and RGB I can see both the diffuse and light passes are causing problems. see attached JPEG.

[vlado]

Are you sure the elements were rendered in linear space (no color mapping/clamping)? Can you post your Maya scene?

Best regards,
Vlado

[bigbossfr]

It is normal (i never use directly raw pass).
You must to use lighting and gi pass to create your raw pass.
Gi raw = diffuse/gi (or gi/diffuse, i have not nuke now)
lighting raw = diffuse/lighting (or lighting/diffuse)

Do not forget to enable "Don't affect colors" in color mapping.

[R_Cyph]

Yes, I am rendering linearly. I have "dont affect colors" checked on in color mapping.

I know the raw passes cause a fringe but they should still be 1:1 with the RGB pass.\

here is my test scene
http://dl.dropbox.com/u/2506168/comp_test.ma

[R_Cyph]

Vlado,

can you take a look at this.

[R_Cyph]

Are you sure the elements were rendered in linear space (no color mapping/clamping)? Can you post your Maya scene?

Best regards,
Vlado

Default

Yes, I am rendering linearly. I have "dont affect colors" checked on in color mapping.

I know the raw passes cause a fringe but they should still be 1:1 with the RGB pass.\

here is my test scene
http://dl.dropbox.com/u/2506168/comp_test.ma

can you take a look at this.

[vlado]

Yes, looking into it now.

Best regards,
Vlado

[vlado]

The problem seems to be that the "roughness" of the material is set to 1.0. Setting it to 0.0 will fix the problem as the "raw" elements are derived by assuming a perfectly diffuse white material with roughness 0.0. Another option is to derive the raw elements from the other two ones (e.g. raw light = lighting/diffuse, raw gi = gi/diffuse) instead of using the raw elements from V-Ray - this also solves the problem, and I would actually recommend doing things in this way.

Best regards,
Vlado

[R_Cyph]

Unfortunately, I can't use the light select pases/diffuse to get my raw passes. There is a hand underneath metal ball with a mtl wrapper set to matte. When I render non-raw lightselect passes the hand shows up as a white object in my lighting passes. when I divide these lighting passes by the diffuse I can get a horrible white crust. The light select passes are using an incorrect diffuse color for the hand for some reason.

[vlado]

Eh, I wasn't talking about the light select passes - they were ok in the file that you sent and there was no need to do anything else with them. Since the light select passes use the actual surface material, they handle the roughness properly. I was only talking about the "raw lighting" and "raw GI" elements, which are derived from the "lighting" and "GI" elements by dividing by the "diffuse" element - since these were the elements that your original screenshot used.

Best regards,
Vlado

[R_Cyph]

I figured lightselect passes or lighting pass would be handled the same. Either way I have problems with light select passes AND regular lighting pass not matching properly.


Could you explain the matte / diffuse light select pass issue? Why would a matte shader appear as white in the diffuse light select passes?

[vlado]

For the regular lighting pass, I already explained what to do.

For the matte shader, the explanation is that the matter shader computes the lighting with a perfectly white diffuse BRDF, ignoring the original surface material, leading to a much brighter result than the regular surface material.

Best regards,
Vlado

[R_Cyph]

I will try and comp the raw light select passes and see if they work 1:1 with RGB. I remember them having an issue too.'

"For the matte shader, the explanation is that the matter shader computes the lighting with a perfectly white diffuse BRDF, ignoring the original surface material, leading to a much brighter result than the regular surface material."

- so if I use a matte shader in my scene I can't use light select passes in diffuse mode?

[vlado]

so if I use a matte shader in my scene I can't use light select passes in diffuse mode?

Nope. I don't really understand what you expect to achieve... if you wanted proper lighting on the hand, why make it a matte object in the first place?

Best regards,
Vlado

[R_Cyph]

I use non-raw light select passes thenI try and extract my raw light select passes by dividing them by diffuse pass. This creates a white crust around the ball because the hand is white in the light select pass. this is why I was using the raw light select passes in the first place because non-raw light select passes were creating a white crust when I tried to extract my raw passes from them.