In Houdini, I usually assign color to primitives (though Houdini defaults to assigning it to “points”). However, if you want Redshift to recognize color attributes (using RSUserDataColor), you need to promote the Cd attribute to points or vertices, as Redshift doesn’t interpret it directly on polygons.

Promoting Cd to points will result in color blending when you subdivide the model, which can create blurred colors. To maintain sharp color boundaries, promote Cd to vertices instead, as Redshift can understand vertex-level color attributes clearly.