Upside-Down Vray Light?

[braddewald]

I've seen a lot of people use a vray light above their scene, but facing up. As far as I can tell, "Emit light on both sides" is not checked either... What does this accomplish?

[BrianKitts]

assuming there's nothing above it to bounce light off of it would accomplish nothing.

 

where have you seen this?

[braddewald]

Evermotion scenes. They have a weird tendency of putting lights in just the most bizarre places you can think of. I've been trying to find a scene so I can upload a screenshot, but I haven't been able to find one. BUT, I know I'm not just making this up, haha. What if I'm wrong though, and they do have "emit light on back side" on? Could there be a different and unique quality to the light coming out of the back?

 

The reason I ask is because I have done a couple of experiments that totally weirded me out:

 

Place a vray light in the left viewport.

place an identical light in the right viewport

rotate the second light 180 degrees so it is facing the same direction as the first light

check out the differences between them in how they affect the test scene.

[BrianKitts]

what wierded you out the viewport performance or the rendering output? I did a quick pass to check and I'm not finding anything different in the rendering output

Edited June 8, 2010 by BrianKitts

[Crazy Homeless Guy]

I have never double checked it, but I always turn off ignore light normal on the Vray planes. By default it is ticked. I always assumed this meant that it would broadcast light from all directions, however when ticked, it will only broadcast light in the direction of the normal.

 

Brian,

 

If you ignore the ceiling plane, it appears that your room is the same. What happens if you turn off the ignore light normal.

[BrianKitts]

right cube has the ignore normals turned off, left one has em on..... no difference that I see.

[braddewald]

I actually cannot re-create the light changing when rotated now either, but I think I figured out why I had the problem: I opened up the scene that it had occurred in. There are two lights that were behind two windows that had been created in AutoCad that were on opposite sides of a room. Upon inspecting the windows I saw that the normals were facing the wrong direction on one of them. Fixing that cleared it all up.

 

I'm still working on finding a scene with a light facing away it, I'll post again if I can find something.