Confused about exterior lighting (in interior scene) best practices

[chris.ellersick]

I'm trying to clear up some confusion as I work through tutorials on my first Arnold project - an architectural interior that views the exterior. If I'm understanding things correctly, the Physical Sky creates an HDR image used for IBL of the scene (no light objects needed). The Physical Sky creates a skydome_light "behind the scenes", which is controlled through the Environment rollout in the 'Arnold Renderer' tab of the Render Settings. I'm inferring that the skydome_light is the mechanism for IBL, whether it's the Physical Sky or another HDR image. Correct so far?

In the lighting tutorial, there is a warning about not using a skydome_light to illuminate an interior scene (which I assume includes Physical Sky as well).... and then the tutorial shows you how to use a skydome_light to illuminate an interior scene. How seriously should I take that warning? Avoid even if you are using light portals? Is the problem with IBL? What is the alternative to distribute sunlight and daylight to the interior of a building? Distant directional light (for sun) and manually creating a multi-light skydome?

[Stephen.Blair · Accepted solution]

Physical Sky is a texture shader that you plug into the color of a skydome.

If you use a skydome with an interior scene, use light portals.