Mtlx ambient occlusion karma (materialX) in Houdini

Mtlx ambient occlusion karma (materialX)

add karma material builder node and dive inside in mtlx standard surface node specular: 0 add mtlx ambient occlusion node (to convert float to color) add mtlx convert node signature: float(color) add mtlx invert node plug it into opacity channel of mtlxstandardsurface (the mtlx ambient occlusion node currently only works with Karma CPU) add grid (in /obj context) and apply the AO material name it: AO_floor in stage context add geometry render settings node primitives: /* ^/AO_floor add karma nodes Karma render settings: +CPU and 512 samples image output -> filters -> Denoiser NVidia Optix Denoiser

node graph

┌─────────────────┐ │mtlx ambient occl├──┐ └─────────────────┘ │ ┌─┘ ┌────────────────┘ │ │ ┌───────────────┐ ┌───────────────┐ └───┤mtlx convert ├────┼mtlx invert ├─┐ └───────────────┘ └───────────────┘ │ │ ┌───────────────────────────┘ │ │ ┌───────────────────┐ │ │ standard surface │ │ │ │ │ │ │ ┌───────┐ │ │ ├─────┤ out │ └──────┼ opacity │ └───────┘ │ │ └───────────────────┘

or just use color channel, for gradients

in geo context: add measure curvature node convecity -> multiplier: 1.4 blur amount: 100 add physical ambient occlusion node concavity -> multiplier: 6 blur amount: 90 also see: https://www.rendorama.com/en/houdini-tips/shadow-catcher-matte-in-solaris-for-karma-xpu-and-materialx/