Hi everyone,
I’m working on a lava cake simulation (MPM solver) and I’m struggling with persistent render noise in Karma XPU. The noise appears mostly on areas where I’m using a mask to blend different breakup/detail layers, so I’m not sure whether the mask itself is causing the problem or if my material network might be too complex (or if I simply need more samples).


Here’s what I’m using:

Renderer: Karma XPU

Denoiser: OIDN enabled

Samples: 250

Ray limits: (screenshot attached)

The noise seems to show up exactly where two different textures/material responses meet. I’m mixing multiple BSDFs based on a mask, and I suspect that might be contributing, but I’m not sure.



I’ve attached the render, and the sampling/ray-limit settings.

I’m not a rendering expert yet, so any pointers or recommended best practices would be super appreciated!

Thanks in advance!

That looks really great apart from obviously the slight flickering

Have you tried rendering without the denoiser just out of curiosity to see if that is the cause?


If so in many render engines there is an option for "static noise" which really helps when denoising is being used.

As far as I am aware Karma doesn't have this as an option on the interface BUT it can be achieved by setting
"husk -- lock-random 0" on the render command parameter of the USD render rop.


https://www.youtube.com/watch?v=0xEdN3q_f4I [www.youtube.com]