Eliminating "Sawtooth" Effect Between Light & Shadow?

RenderNovice

I see this problem frequently right at the boundary of a shadow -- particularly when the light source is at low grazing angles to the illuminated surface.  (see attached example)  

At the "lights" tab, I've experimented with changing "Light Geometry" from "Point" to other options -- like "DIsk" or "Sphere," and this sometimes seems to reduce -- but not eliminate -- the effect.

Surely someone knows what's happening here and how to correct it?

Thankyou!

 

DustRider

Increasing the render subd (subdivision) level of the model by 1 should fix it (but it will use more memory). If you don't know how to do this, select your figure, go to the parameters tab, select "Mesh Resolution" and the render subd level will show, increase by 1. If this doesn't eliminate it, you can increase again, but it will use more memory, and could cause the render to fall back to CPU if your using a GPU to render.

Hope this helps!

RenderNovice

Awesome -- experimenting with this.  Thank you DustRider!

lexbaird

nicdf16 said:

Surely someone knows what's happening here and how to correct it?

What is happening is you are seeing the shadow hitting the geometry of the mesh. There is actually an slight angular joint between polygons on the mesh that is faked into looking smooth, but it shows under raking light. Increasing the subdivision divides each mesh polygon into smaller sections, which reduces the effect but increases the processing time. For each quad polygon, you now have 4 polygons, for example.

You can try changing the angle of the light a bit, which sometimes fixes this. You can also try adding a smoothing modifier.