Disable Primary Rays in Houdini

How to Disable Primary Rays in Houdini

A common thing to do in 3D workflows is to make an object invisible to the render engine. Either completely invisible or invisible but still cast shadows and reflections. In geek parlance, no primary rays but secondary rays. If you are a Cinema 4D user, you can achieve this through the Seen by Camera option in a Compositing Tag. Houdini users are accustomed to the Phantom option. At least this is how I came to learn it by. So how to we disable primary rays in Houdini?

Phantoms Objects

In early versions of Houdini, you could disable primary rays by checking on the Phantom switch. Simple enough. Just good old fashioned one-click wonder.

Seen By Camera in Cinema 4D
Seen By Camera in Cinema 4D & The Houdini Equivalent

 

This option is accessed differently now. I didn’t notice in what version this changed but as of Houdini 15.5, the Phantom switch is no longer there. If you go to the object’s Render tab, you will find something different. This is now know as Render Visibility. Which makes sense. It also includes a dropdown menu with several other options. In here, you will find the Invisible to primary rays or Phantom option. We are back in business!

Disable Primary Rays in Houdini
Disable Primary Rays in Houdini
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990adjustments

990adjustments

I am a motion designer & developer based out of South Florida. When not designing or animating pixels, I wrangle some code. If all else fails, I watch Twilight Zone, I Love Lucy, or Three's Company reruns.