This method will give similar results as “multi displacement 2”, when rendered in maya with mental ray. I developed this method while in the middle of a production and it worked on several charcter elements (models) perfectly.
Warning! If you try this method on the models which come with Z3 (Demo head etc…) without first preparing it in maya it won’t work. So follow the steps below.
So far I have found this method will work with any basemesh that comes from maya or created in Z3, provided that it has been properly prepared in maya prior to generating displacement.
*Note: You will need convertfile.bat, which automatically converts tif/targa/image files to .map files for mental ray, which can be found here:
[http://www.datafilehost.com/download.php?file=3ec7a97e](http://www.datafilehost.com/download.php?file=3ec7a97e)
**Model must have UVs assigned to it and normals must be set to face so that they are perpendicular to the surface pointing outward,
this process must be done in maya prior to creating displacement map in Z3.
*** If the model poly count isn't too high export the hi-rez from Z3 to prepare in maya, then re-import and reconstruct the subdiv levels.
Otherwise export the lo-rez obj, prepare in maya, re-import into Z3 and transfer the hi-rez details from the original model to the new model, using whichever technique suits the model (these techniques are covered in great detail on the pixologic site).
1. Prepare lowpoly model in maya, position model Yaxis up and Zaxis forward, assign UVs, freeze transformations,set normals to face, delete history and export.
2. Create displacement in zbrush3 and take note of the "Alpha Depth Factor"
3. Export the displacement Alpha and convert to .map file using "convertfile"
(drag and drop the displacement map file onto the convertfile and it will automatically place the .map file in the same folder)
4. In Maya set up displacement shader and mentalray approximation for Lowpoly model
5. Take the "Alpha Depth factor" number and divde by 10, then divide it by 3, then multiply by 2 this will give you the Alpha Gain
Take this number and divide it by -2 to give you the Alpha Offset (half and in negative)
e.g Alhpa Depth Factor = 4.455
4.455 / 10 = 0.4455
0.4455 / 3 = 0.1485
0.1485 * 2 = 0.297
0.297 / 2 = 0.1485
Alpha Gain = 0.297
Alpha Offset = -0.1485
Note: Make sure to turn on Alpha Is Luminance.
6. Alpha Gain acts as a multiplier for the displacement height. If the model needs to be scaled you can enter the scale factor to adjust the maps accordingly.
Multiply the Alpha Gain and Alpha Offset by the scale factor of the model.
for example, lets say the model is scaled by 13.745%
take the Alpha Gain and Alpha Offset and multiply it by the scale percentage
0.297 * 13.745 = 4.082
-0.1485 * 13.745 4 = -2.041
The new values are as follows
Alpha Gain = 4.082
Alpha Offset = -2.041
Zbrush3 settings for exporting lowest subdiv model
Preferences palette>Importexport
Turn off iFlipY and eFlipY
(do this step if the model is flipped in the Y axis when imported into maya)
Tool palette>Export
Make sure only Obj, Qud, Txr, and Mrg are on
(by default Grp is on instead of Mrg, switch them)
Zbrush3 settings for Displacement
Tool palette>Displacement
DPRes = (what you like,keep in mind a multiple of two will work best)
Turn on Adaptive, leave smoothUV off
Turn on Mode and then hit Create DispMap
Alpha palette
Select the alpha which is the displacement just created
Flip it in V, and export as filename.tiff
Maya settings for mental ray
In the Attribute Editor under File Attributes for the file texture node set Filter Type to Mipmap
Turn off Feature Displacement in the lowpoly models' shape node
Under the mentalraySubdivApprox node in the attribute editor select Spatial for the Approx Method,
set the Min Subdivions to 3 and the Max Subdivisions to 5
Set Length to 0.010 (a length of 0.10 will work as well)
Render!
I hope this is clear enough for all Z3 users to follow. I will eventually post a step by step tut with images, until then I will try to answer any questions that may arise.