What happened to my shadow?

Could someone explain why this happens.
On the left is a sphere that looks fine.
On the right is the same sphere with a bump using a cloud texture.
Why is the shadow all messed up with the bumped version?

Light samples… increase them

There is only one light in the scene. A point light.
I tried changing the Sampling settings, but it didn’t help much.
I raised the “Shadow” “Sampling” to 32 and 64, and that didn’t do much.
I played around with the “Threshold” but that didn’t fix it.
I also tried “Constant QMC” and still nothing.

Any idea?

I think it is self-shadowing. Are the faces roughly where the shading is?

You could try subdividing more, or possibly applying the subsurf at a higher level?

Sorry i was confusing it with a similar texturing problem.
@organic, the does help, but it’s really impractical

I didn’t have a subsurf applied.
I took your suggestion and did apply one, and after setting it to 3, the shadows look pretty good.
It’s odd though that you don’t need a subsurf for good shadows without a bump, but by simply adding a bump texture makes the shadows expose the faces in that weird way.

Hmmmm…Is this a bug?


No, not a bug. It is a well known problem in ray tracers. I think it is called the shadow terminator problem. I’ve been trying to find information online, but I can’t remember the appropriate keywords.

This is the best I can find for now:-