I experimented with a cylinder (primitive) and procedural tile texture. At subd=0 it produces only over the top shadow shadow effects but messy to no distortion of the mesh. Units meter, displacement 1 (a cm?). No scales on the cylinder. Just as poser makes it. I grouped the sides and top, to create to materials, sides and top, so I could apply the texture to just the sides.

The tiles were gray 50%, the mortar, black. smooth of 1 on that.

Same thing, with subd jacked to 7 (the same as when it's 4, really).

It seems the subd needs to get the mesh down to the level of detail required by the displacement map. Manually. Am I missing something, here? This seems a bit stupid since, you know, computer... really fast ginormous calculating machine should be doing stuff like this FOR me. It's 18 Xeon cores and 128GB of RAM, and a really fast GPU (which I can't use because... well Mac. Apple doesn't play nice with devs. Nvidia doesn't either, but "winvidia" is a market worth the effort :)

Also, the smooth texture doesn't seem to produce a smooth curve for the displacement. Is there a better map I need to use? I can only go 256 shades of grey. But the result doesn't seem to be 256 levels of displacement between the extremes.

I could deal with that but for the shadows. They don't make any sense at all.