Dan Lee
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Karma LPE Problem With Treat As Light Source April 24, 2024, 10 a.m.
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).
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).
Karma Gold . pyro geo light March 8, 2024, 5:42 p.m.
Volume geometry lights aren't supported in XPU (https://www.sidefx.com/docs/houdini/solaris/karma_xpu.html [www.sidefx.com] see 'Lighting' section for more detail)
Karma stuck frames when VDB's have animated transforms Jan. 17, 2024, 1:54 p.m.
Hi. Can you try daily build 20.0.582 (or newer)? It contains fixes to the bug mentioned in that thread.