V-ray Clipper, Material ID Color and other Render Elements issues on GPU

[Areczan]

I already contacted Support via email about this, but as I'm seeking answers whenever I can I'll try to find another user who encountered or knows a solution to my issues with V-ray.

Straight to the point:
1. I get huge noise on Material ID Color render element while rendering with CPU. On CPU+GPU mode edges are sharp. This is the biggest issue I'm struggling with.
2. While rendering with CPU+GPU, V-ray has trouble differentiating Material ID colours when an object has one material applied to faces and another (by mistake, for example) on a group. As a result, it appears black.
3. Material ID Colour with CPU+GPU mode renders TwoSided materials as black.

Colours on Material ID Color Render Element on CPU look fine, but the noise makes it useless. It would be a workaround to points 2.-3. to render a scene with CPU+GPU (as I understand GPU rendering has its limitations) and then only render Material ID Color on CPU by turning off all light sources if it didn't have that much noise. This way I could render everything faster and keep useful tool which Material ID Color is for later us in Postproduction.

4. While Batch Rendering on CPU+GPU, V-ray ingores Section Planes randomly (it's not a thing of a single Section Plane). Is there any way to set up Scenes settings in Sketchup so that the Section Planes were active in each Scene?
5. Render in CPU+GPU mode makes RawShadows, RawGI, RawLight, etc. appear as completely black.

I would really appreciate any help or ideas how to make these issues go away

I'm using V-ray 4.10.02 and Sketchup Pro 2019

[konstantin_chaos]

Hi,

1. I get huge noise on Material ID Color render element while rendering with CPU. On CPU+GPU mode edges are sharp. This is the biggest issue I'm struggling with.

The noise issue is strange. If you can share a simple example scene that produces it, you'll help us a lot.
The 'hard edges' in GPU mode also sounds interesting.
Please attach some images that illustrate the issue.

2. While rendering with CPU+GPU, V-ray has trouble differentiating Material ID colours when an object has one material applied to faces and another (by mistake, for example) on a group. As a result, it appears black.

This is going to be addressed in the next update.

3. Material ID Colour with CPU+GPU mode renders TwoSided materials as black.

This is a known limitation.
As a whole material ID masks don't function well with Two Sided materials.

4. While Batch Rendering on CPU+GPU, V-ray ingores Section Planes randomly (it's not a thing of a single Section Plane). Is there any way to set up Scenes settings in Sketchup so that the Section Planes were active in each Scene?

This is a bug that we're currently looking at.
There will hopefully be a solution for this soon.

5. Render in CPU+GPU mode makes RawShadows, RawGI, RawLight, etc. appear as completely black.

This is a known limitation.
You can on the other hand re-create the listed elements using ones which are supported.
The RawLight for example can be produced by rendering Diffuse and Lighting and then divide them.
Lighting / Diffuse = RawLight
GI / Diffuse = RawGI
Shadow / Diffuse = RawShadow

Thank you for reporting these issues.
Another thing you should consider is using Cryptomatte instead of the Material ID Color element.
Keep in mind it requires production bucket render mode to be used (Progressive disabled, Interactive disabled).
It'll on the other hand give you perfect masks and with need to set ID Colors in materials.

Regards,
Konstantin

[Areczan]

The 'hard edges' in GPU mode also sounds interesting.

Well, I mean that GPU result looks nice and the edges of objects are not jagged like they are in CPU mode.

This is going to be addressed in the next update.

Any idea when it will be released?

Thanks for clarifying the limitations. It makes me stop digging for something I can't change

Take a look at the images below that might help you to better understand my issues:

[konstantin_chaos]

Hi,

The jagged edges issue is caused by the overall image quality.
It seems that the GPU produces higher quality image and thus the masks also look better.

As far as the two-sided noise is concerned - I can't reproduce the issue using the latest update.
Can you give it a try and let me know if your scene renders better?
https://download.chaosgroup.com/?platform=56&product=47

The other issue where some object were rendered black should also be resolved now.

On top of that in the latest version there is no longer a need to assign Material ID colors to all scene materials to mask them.
We have implemented a new matte element called Material Random Color which will give you similar result, automatically assigning random colors at render time.

Regards,
Konstantin