I think a bit of artistic licence is used sometimes for visual effect, using a black one pixel rivet set and placing another overtop in white, offset one pixel in whatever direction your 'light source' is intended gives a nice '3D' set of domed rivets. But this is blatantly wrong if used on an aircraft which used flush rivets where the most you'd get is a slight dimple (or crease along a line of them) effect. A good example is the Tempest, which had predominately flush rivets except certain areas of the fuselage, and the H. Stab, which had domed headed ones. It's a toss up between anal retentive accuracy and artistic good looks.