Virtual objects are timeless—they are rarely left derelict for prolonged periods, whereas object degradation is a universal phenomenon in reality, giving a strong impression of the lapse of time. Hence, the aging of virtual objects is a vital topic in the pursuit of physical realism in the area of Computer Graphics.
In fact, many developments in the process of weathering have been offered to depict outdoor objects as having suffered rain and wind damage. Especially, metallic surface rusting is a widespread degradation phenomenon featuring varied manifestations, and hence there exist many known weathering methods targeted at metallic surfaces.
However, most of the existing methods do not consider the effect of rust-preventive paint, which is usually applied to the real metallic surfaces. Besides, few metal weathering methods have not supported 3D deformation, which is also required to express realistic coating film deterioration.