When I view large parts with very large curvature (1100 inches ID) I can see hidden lines if they lie close to the surface. I have an 1100 inch ID cylinder that is very thin (3/16). There are ribs on the outside. When I view the inside I can see the base of the ribs unless I zoom in very close. Image quality settings are set to the highest resolution possible and optimize edge length can be checked or unchecked. Also, picking edges on this large diameter is somewhat of a problem because edges and faces don't match up very well and seem to "dive" in and out of each other even when zoomed in. AMD64 FX53 NVidia FX3000 SW2004 SW2005