I’m first create under max a low poly of the old pillar with 1440 faces, unfold the low, and then I export all under mudbox to modelling all the asperities. At the end my pillar take more of 360 000 ploys. Then I extract the displace and the normal. Under max, I use a VRay displace and import the diffuse and specular map create under Photoshop.
I make the scene to A at Z in only 3 hours, and wait the same time for the render.