Strange shadows on flat surface -help

I can’t seem to figure out why these shadows show up on this mesh. I hope the screenshot helps. The render has the same thing. I noticed it only shows up on “set smooth”. How do I get rid of them?
(Click to enlarge)

Ok, think I got it… maybe (starting to think in “blender”). I selected the top faces and extruded, but left at the 0 position.

I sort of understand what’s going on. I think set smooth is looking for an edge to bend, so I had to “fake” a new edge to “trick” the set smooth function, thus leaving the new faces alone. Is that right?

Here’s the result, including what it looks like if I remove doubles.
(Click to enlarge)

Ok, so now I can see that this question/thread probably belongs in the modeling forum. At first I thought it was a rendering issue. Feel free to relocate this to the right forum :slight_smile:

Kind of… these are smoothing “irregularities”. But please don’t be fooled by them, it looks much different in final render, so don’t change geometry just to please the preview.

To avoid these you can use auto-smooth, which means that edges with a large angle will not be smoothed. Doesn’t show in preview either.
Or you can use the edge split modifier, which does basically the same as you did by hand (adding geometry), but non-obstrusive. And this one shows its result in preview.

Edge split modifier… does that set some kind of threshold for the set smooth?

Umm. Edge split gives me this:
(Click to enlarge)

Edge Split modifier does make certain edges sharp (and does plain planes in preview). You can decide which ones should be sharp either manually or by angle.

I guess you still have your 0-extruded faces in the geometry. Remove them (remove doubles should do).

Woops! Had too many layers on during the render… :slight_smile:

Thanks Inmare!

an easy way around this is modaling everything with subdivision serfises, and adding more loop cuts(control+r). but this results in very dance meshes, witch take longer to render. an advantage to this metherd is bevaling edges is verry easy to controal, NOTHING has truly sharp edges. you decide witch metherd you want to use.