:displacement maps - from zbrush to mental ray

What a pain but I think I have it working - spent lots of time (days) with the zbrush-maya integration guide and zbrush forum: I think I can get the same amount of high frequency detail in my maya renders as in the original ZBrush sculpts - here's a test mental ray render of the head of tortoise - the model is a test and may change later.

Here's the quick code for zbrush's displacement exporter:
DE-LBEK-EAEAEA-R32

I exported 32bit 2k and 4k displacement maps which were converted to the mental ray native .map format. Plugged them into the mr displacement shader using alpha gain 2.2 and -1.1 offset. In the approximation editor, I used subdivision approximation with min. 4 and max. 7 subdivisions and 0.050 min. length to get the details to resolve properly.

2k maps are going to be about 64MB while 4k maps are reaching ~266MB - probably will use 2k maps for the most part except for closeups where 4k will be necessary.

Render times aren't terrible - the above render with the 4k map - base model: ~4000 polygons tesselated to over 1million polygons took ~2min.