In Houdini 19.5, if you’re seeing a “Error: /obj/box1/dopnet1/vellumsolver1/ocl_neighborsearch_grains/neighborsearchcl1: OpenCL neighbor search supports only uniform radius particles.” in the vellum solver at around 8:20 into the video, the solution is pretty easy: dop net > vellum solver node > Advanced Tab > expand Grain Collisions > uncheck “Assume Uniform Radius.” This is covered later in the video when Moritz is dialing in simulation values.
In Houdini 19.5, if you’re seeing a “Error: /obj/box1/dopnet1/vellumsolver1/ocl_neighborsearch_grains/neighborsearchcl1: OpenCL neighbor search supports only uniform radius particles.” in the vellum solver at around 8:20 into the video, the solution is pretty easy: dop net > vellum solver node > Advanced Tab > expand Grain Collisions > uncheck “Assume Uniform Radius.” This is covered later in the video when Moritz is dialing in simulation values.