AAaronLi

I've found that Karma can render DCM(Deep Camera Map) output. This is a good feature.

But I didn't found how can I use DCM as matte for Effect, Instead of importing the scene and then setting the Holdout Mode to matte in the geometry render settings.

It's like rendering with Mantra and setting the camera parameters in the SOP.



Does Karma have this feature?

Any help would be greatly appreciated.

- Aaron

This one is a simple file with my settings inside.

dlee
Hi, if you enable "Treat as Light Source" the emissive material is treated as light and not emission, so it will only contribute to LPE AOVs that accumulate direct/indirect lighting (i.e. expressions that end with 'L' not 'O').

As for the render being darker without light source: It's because diffuse indirect ray hitting transmissive surface (which then hits emissive surface or anything for that matter) is a caustic path and true caustics is disabled by default. Fake caustic is automatically enabled on MaterialX-based transmissive materials, so the colour of shadow rays for the light source is adjusted and thus appears brighter. Otherwise you'd have to enable true caustics (via rendergeometrysettings LOP on the glass object, or globally).

I understand. I've always understood it wrong before. Thank you so much. I tried to add an LPE Tag to this object, then write a custom LPE, only retain this object as the influence of the light, and then get the final result. The LPE tag of this object is `pemiss` and the LPE Expression is `C.*<L.'pemiss'>`