Shadow doesn't "respect" surface imperfections
 

I have a light pointed generally toward the camera from behind that aqua glass wall..with RT shadows turned on, that light casts a perfectly smooth shadow onto the purple surface, while that same surface shows a squiggly reflection of the shadow-casting object.

Can anyone give me a hint as to why the shadow isn't also distorted somewhat by the surface distortion, which is a procedural bump?

thanks!

Johnny

http://www.bluemitten.com/shadow.jpg

You're using a procedural to simulate surface bump.. it's not real bump and the shadow is following the true geometry. Try a deformation of the surface geometry.

What he said.

Bump maps only effects the surface normals. Shadows don't really care about which way a polygon is heading, only the actual position.

Ahh...ok...that makes sense...

thank you!

J

Hmmm...if shadows only keep surface normals in account, would it be save to asume that a normal mapped floor would affect shadows?

No no, it's the other way around. Shadows don't care about the normals, only the position.

Then again, how is it that the reflection of the hypo is distorted by that very same procedural? The bump is not in the reflection channel of the surface, but in its bump channel.

That surface's geometry is no more changed for the reflection than it is for the shadow, since it's a procedural surface element.

Thanks,

J

Because Reflections depends on the surface normal.