Interior Lighting - Using Hemi-Lights Under The Floor?

I recently purchased Digital Lighting and Rendering, and part of one of the methods mentioned for lighting a room was to use hemi-lights under the floor pointing up towards the ceiling. Does anyone here use a method like this? I’m assuming the only way to do this is using render layers (with the walls, ceiling, and hemi-lights being on one render layer) but figured I’d ask around to see if anyone knew exactly what the author meant.

Hemi lights are not affected by geometry at all so their placement is like the Sun, you can put them anywhere. Try it, place a hemi inside a cube and it will still light the scene. The default energy of 1.0 is too bright, IMHO, so when I add a Hemi to my scene I drop it down to 0.1. You can use Hemi’s for a more ‘graphic’ look in your final render to bring up the dark shaded areas of geometry without adding the overhead of Ambient Occlusion to your render time.

Right, they both simulate light sources from very far away. But the example I gave has the lights outside of the room, underneath the floor pointed at the ceiling. I guess I’ll have to test it more later, it just doesn’t seem that this would help fill a room with light. Wouldn’t be the first time I’ve been wrong though. LOL.

As he said, hemi lights don’t care about geometry, they will light every surface as if there were nothing in the way.

Also, I hope you weren’t planning on trying this with Cycles. No support as of now.

Ya, I noticed that when playing around a bit last night. Anyway, thanks to the two of you for answering my question.