Matching vray displacement in zbrush->apply displacement


hi there

i know how to get displacement from zbrush->v-ray for maya, but i need to apply the displacement map and create geometry for a liquid sim (surface is hi res tree bark).

im not sure where the displacement map came from (a freelancer), but in the maya scene, the vrayDisplacement attrs have an offset of -10 and a magnitude of +20 , which suggests its 16-bit rather than 32-bit float.

bringing the .tiff into zbrush (tried 32 bit exr as well) and applying displacement to geo results in a crazy overinflated model.

the tiff looks like its 0-1 in nuke.

i think what i need to do is to get the min and max values of the displacement map after whatever vray is doing to it with the offset/ scale and somehow renormalize that into a format that zbrush will play nicely with. i assume whatever vray is doing is linear, but im not good enough with math to figure that out (i tried offsetting -10 and multing *20 and writing that out as an EXR then using that in zbrush, but no dice.

this is ironic because its the reverse of the usual process. maya also does not support converting displacement to polygons in vray, only maya nodes or arnold.

any advice is greatly appreciated.