Dan Wood

I've yet to dabble with Karma, but a while back I got into Octane - it seemed a lot better than Redshift for technical renders like water rendering with internal scattering, volumes in general, etc... and then they brought in the Progressive Photon Mapping kernel, which has been an absolute game-changer for light propagation in water renders.

I'm assuming photon mapping isn't in Karma yet... just wondering if there's anything on the roadmap to add something similar to the Octane PPM kernel into Karma XPU? Octane is great, but I always appreciated the simple customizability of using Mantra, so it'd be good to get back to an integrated setup.

Can't check over it myself at the moment, but I'm wondering if the group-expression version of the intersect command might be the way to go.


If you have each mesh assigned to a primitive group beforehand, you may be able to use a standard group pattern in that (string group) parameter... along the lines of "* ^thismesh" for intersecting everything excluding the current mesh.

Assuming you want to cull on a per-connected-mesh basis, rather than a per-point/primitive basis... you could perhaps start with the intersect vex command, make a check along the normal from each point in a mesh, store whether it hits anything or not... then use the promote note to aggregate the hits per mesh, convert number of hits into a percentage of total point count, and set a threshold to delete the whole mesh, say if 90% of intersect checks hit something, then delete that mesh.