I have found that when the mid level is set to 50 in Z brush so that 128,128,128 grey is Zero displacement, Z brush is actually outputing 149,149,149 as Zero displacement, which is causeing bloating in the displacement renders.
THis became apparant to me while using Mental Ray and setting the alpha offset to half of the alpha gain, so the AG 1 = AO -.5 which is correct for getting the proper displacement from the textures from Zbrush . I corrected this by taking the dis map into photoshop and lowering the brightness value until the nuetral grey area read as 128,128,128 then the Mental ray render was correct.
I tested it several times and Z brush always sets the nuetral displacement value to 149,149,149 which is incorrect is there something that I have set wrong, I thought that if you set the Mid level in the displacement options to 50 that you would get 128 for grey which is the middle of 0 - 255
has anyone else noticed this??
on a side note what I do to determine if my displacement settigs are correct is imoport the high res mesh from Z brush into Maya (yeah kinda slow but worth it) for reference then I put my low cage object directly behind it with an ambient red shader on it, so when I render from the side ortho view I can see if the red displaced mesh is sticking out further than the high res mesh in front of it.