How to create projection material with geometry but full transparent render?

[dt_developer]

Hello, I am trying to reproduce the following behaviour:
With replicator, I create a cube with visible argument as False and a project material with an image in the albedo input that will generate a mask in semantic segmentation. For some reasons like the render could be different from the mask (example that render contains transparency that mask doesn´t) I would kile to achieve is that project material only generates data for the semantic segmentation but without being rendered (of renderer full transparent keeping the geometry generated by the shader, if this is possible).

I have tried multiples combinations and configuration modifying the project PBR material shader and I am not able to get a geometry based on the mask, full transparent that generates data into semantic window.

Could you help me with this?

[Simplychenable]

@dt_developer i am just another user, and although an old thread explored something you are looking for but it’s not using project materials. that said, wanted to throw that out there in case it has something that might offer something of relevance:

How to render the absence of a prim/mesh or part of a prim/mesh?

Hi everybody, High level what I would like to do is train a model to detect that a chunk of material is missing from an object. In Omniverse terms I believe this fundamentally comes down to whether a prim can be invisible to the RGB renderer while visible to the InstanceSegmentation renderer. I am using Omniverse Replicator in Isaac Sim, and I have been digging around in the code to better understand how the renderer works, but I can’t seem to find a solution to this. I wish I could select whi…

there was, however, another thread on project materials where the use case may be more in line with what you are after; however, it seems like the dev/mod also has mentioned such approach (invisible to RGB but visible to segmentation) is something of a challenge?

Segmentation behind transparent surfaces

Is there some way we could assign “doNotCastShadows” to one part of the mesh and not another or some part of a material and not another? Not to my knowledge. “doNotCastShadows” is a mesh prim attribute. I’ll see if I can pull over the MDL experts’ ear see if they know more. I checked on the ability to render only segmentation, without the heft of the RGB. Currently no. This particular ask came up for a different use case, so we’re looking into it. If we do address this, it wont be soon thoug…

[dt_developer]

Thanks for your response @Simplychenable . I have already checked the second thread you mentioned, and as you said, it seems that currently is not possible to perfomr this without a 2 step replicator iteration (which is what I would like to avoid).
The first thread shows kind of another 2 step solution but maybe withing the same iteration? (at least the global iteration although the solution has two set two times the environment.
Anyway I will have a look on that solution in the meanwhile another solution fo the source question.
I guess that if it could be possible for a PBR projection material that geometry would had been modified within the shader with the opacity but renders also use a full transparent material, would be the solution (in case the semantic segmentation render would not need anything else like shadows)

Hope on that kind solution