I created a simple bowl (see setup picture), set smooth and added subdivision levels. I made test renders, unfortunately I see two set of artifacts even if I keep raising the subdivision level. The render is the internal Blender renderer, with default settings.
The artifacts are marked. The red one is the one I can’t get rid of (stripes in that direction, on the right of it), and am interested in removing it, although the blue one is interesting too (I would expect a circular reflection, yet it has a kind of irregular shape, possibly because of the geometry…)
Do you guys have any idea of what is the error? (It is not the JPEG itself, I tested it with TIFF, same result.)