3D Bas-Relief Medals
3D (3 Dimensional, 3D Relief or bas-relief) medals are medals with bas-relief carvings. Bas-relief is a kind of sculpture in which shapes are carved so that they are only slightly higher than the flat background and no part of the modeled form is undercut. The projecting image in bas-relief sculptures has a shallow overall depth (1 to 5 scale), as on coins, on which all images are in low relief. In the lowest reliefs the relative depth of the elements shown is completely distorted, and if seen from the side the image makes no sense, but from the front the small variations in depth register as a three-dimensional image. More about bas-relief here.