Transferring Color Attributes in RenderMan for Houdini (and a few other quirks)

Final render for my first project in RenderMan

For my first project for VSFX 319: Programming Models and Shaders (aka the RenderMan class), we were assigned to make a pop-up book. Although the class was taught entirely in Maya, I chose to do the assignment in Houdini to stretch my skills (and because it’s currently my favorite package to be in). I’m writing this as a reference for myself if I ever need to come back to it in the future, and for whoever else stumbles upon it within the murky depths of the internet.

Versions used were Houdini 17.0.352 and RenderMan 21.0.

Transferring color attributes:

Once you’ve gotten all your color attributes assigned, throw down an attribute promote SOP. Promote Cd from a point attribute to a vertex attribute. Then put down an attribute rename SOP. The right-most tab is labelled RenderMan. On the leftmost column, put down the Houdini attribute to be renamed — in this case, it’s Cd, the color attribute. Cs is the name of the color attribute in RenderMan, so we need to rename it for RenderMan to recognize it. The RiType can be left as a vertex float or changed to a vertex color; both work. Now you can plug this into your material and you will be good to go.

Rendering:

The Render to MPlay button will redirect you to Image Tool, which doesn’t seem to work well with the transferred color attribute. Use Render to Disk instead.

The denoiser and integrator settings are in the Properties > RIS tab. The integrator setting is left blank by default and you can render just fine with it blank, but to manually set the integrator, you need to go to your risnet in the SHOP context and create a visualizer or a path tracer integrator.

Getting Cd/Cs and textures to play nice:

If you have colors that are assigned via Cd and colors that are assigned via texture in a material in the same geometry object, RenderMan will not recognize the texture. Object merge them into a separate geometry object and they will render just fine.

Lights:

RenderMan lights won’t render at all if Intensity is set to 0, unlike some other packages/renderers that are perfectly fine with that. Exposure can be set to 0 for RenderMan lights.

You can take a look at my hip file here.

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Jessica Beckenbach

Jessica Beckenbach

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Houdini / Technical Artist. SCAD Visual Effects ‘20. Lives and breathes Houdini, Nuke, Unreal, and (sometimes) Maya.