Expectations for PortalLights

Community USD
1

After looking closer at UsdLuxPortalLight, we noticed that because portal lights inherit from LightAPI (by way of BoundableLightBase), they are now carrying a lot of “light-ness” with them (intensity, exposure, etc…).

Was this intentional, or is this perhaps an unintended side effect? If intentional, what sorts of workflows/applications are there, for these features on portal lights? Our expectation was that a portal light is just a rectangular shape with a transform on it, associated with a dome light.

Thanks!

2

Just to add a bit more info from some research/customers (and apologies if I’ve mistakenly represented anything):

  • Arnold, Karma, and Prman are do not consider portals as lights; they are just for guiding samples.
  • Redshift also guides samples with portals, but explicitly says portals are area lights.

USD tends to carry Renderman assumptions, which makes me lean towards the portal light having LightAPI applied being unintentional; but it would be great to have some clarity.