Karma renderer

physically-based path tracer renderer

· Source ·Karma XPU · Application software · Computer graphics · SideFX Houdini · Karma Sink ·


Karma is Houdini’s physically-based path tracer, which is deeply integrated with USD (it uses USD as its scene description format and acts as a Hydra render delegate). While it shares some concepts with Mantra, Karma is a completely new renderer intended to replace Mantra for new projects.

Karma can render traditional Houdini Object-level scenes that use the Principled shader (either by rendering them directly with the Karma render node or importing them into USD with the Scene Import LOP).

Karma does not support most VEX shading functions (with the exception of certain uses of trace). It does not support VEX geometry/point cloud lookup functions. It does not support material style sheets which are now deprecated.

Karma has two render engines: Karma CPU, which runs entirely in software on the CPU, and Karma XPU, which uses CPU resources and also takes advantage of the GPU and hardware acceleration. As of Houdini 19, the CPU engine is production ready, while the XPU engine is an alpha-quality preview release.

Because it must run in the more limited environment on the GPU, XPU drops support for even more legacy features than Karma CPU. Karma XPU will never support VEX-based shaders at all. Currently it supports the built-in USD materials (such as the USD Preview Surface), and MaterialX, which is probably the future of shading in Karma.