So I was playing around with ambient occlusion and compositing and found this (Blender Internal renderer):
Both cubes consist of quads only, not triangles. The right one is subdivided a few times.
As you can see, for some reason Blender’s conversion of quads to triangles results in small artefacts in either the render or the AO pass that become visible when combining image and AO in the appropriate way. Weird.
(and yes, the name of the attachment is wrong: It should be triangulation:p)
Tesselation.blend (59.6 KB)