The physical model is a plaster cast that was found on the street more than twenty years ago. The plaster is pink, and has faded un-evenly over the years through sun exposure.
The detail is baked from the full res 3.3 Million poly model onto a 45k poly model. This test uses a 4k un-lit albedo, and a 2k normal map, plus a quick 2k roughness map.
The model was created from 219 photographs taken in a diffuse lightbox, and masked before calculations.