OTOY Forums

Hello everyone,

I have a big problem with the cryptomattes.

The following scenario:

I have a group/collection that consists of several hundred objects with many different material. Now I want to create a cryptomatte (CM) for the whole group/Collection and I can't figure out how to do it. The Object and Instance ID CM is completely colorful, there is no Asset CM like in Cycles as far as I know. Accordding to the manual there should be a render layer CM but there is none under the Cryptomatte tab.

Trying with the Pass ID does not work neither.


I found a workaround by using the Mat ID and add all different materials to one single matte in my compositing software. It works but I wonder if there is an easier solution.

Does anyone know how to solve this?

Thank you very much


Win10 - RTX 4080 - Octane 28.8

I guess there are several ways to get to a solution. Fortunately Octane has a lot of passes to dig into. But the quickest way would be to borrow the Baking ID pass (if you don't use it) and assign different Baking ID's to the group of objects you want to separate. Object Layer Color would also be an option but it's not that easy to assign a color to multiple objects at the same time. I would have to solve that via a script.

I've added a button to my Octane Tools that copies the Object Layer Color from the active object to all selected ones. Using that you can now also use the Object Layer Color pass to separate your collection.
You can download it here (works with Blender 3.x) ... http://www.argfx.at/upload/octane_tools_0.2.1.zip

Here is the version for Blender 4.x ... http://www.argfx.at/upload/octane_tools_0.3.1.zip

Hi Andreas,

thank you very much for your help. I really appriciate it!.

I installed the newesst version of your Octane tools but I didn´t get the "Copy Object Color from Active" runs properly. So what i Did is just select my objects and hit the buttton. My cryptomattes Layers looks still the same. The white image is the Render Layer ID Pass, the colored is the Object ID Pass.

Did I missed something?


thx alot!

You need to use the "ObjLayerColor" pass in the Info section of the render passes. Or for the other option you can also use the "BakingGroupID" pass.

Hi Andreas,

sry I missed the correct spelling. The white image is the Object Layer Color Pass not the Render Layer.

I will try with your baking ID method hence I´m not sure if it´s supported by Cryptomatte.

I found that is there is shading node named object layer color. But i only found some C4D infos about this mystic node. Not sure how to use it or for what is it intended.


cheerz Chris

But isn't the black/white version above what you want?

I would like each cloud to have its own ID color. There are many small clouds in front of the large clouds that are not visible now. I can solve this problem by giving each cloud its own material ID, but ideally it would work via the object ID. It would also work via the RenderLayer ID, but the Render ID Layer Pass cannot be interpreted by the compositing software /Fusion/. This drives me nuts .....Such a simple task turns out to be super complicated ...

Then just assign a different Group Layer Color to each of those cloud groups and render the Group Layer Color pass out. Doesn't that work?