When rendering amodel using phong shading (activating “smooth”), I allways get these triangular render errors in the area between shadow and light. Looks like the smoothing simply stops working in these areas.
I have tried to both cleanup and to triangulate the mesh, but it doesn’t help. Only workaround is to add a subdiv modifier and thus make the triangular errors so small that they don’t show up to much.
The problem appears in both the internal renderer and in Cycles.
Do I do something wrong, or is this a known issue?