Displacement/Normal Maps – After changing the export settings I managed to export Displacement and Normal Maps for each object in Zbrush, using the ZPlugin MULTI MAP EXPORTER.
I selected a subtool and set the Map- and preferences preferred for export. There is a plugin for merging all subtools as well, which can give you one map for the entire mesh at once. However I didn’t get that plugin to work, so I simply merged all the maps later in photoshop.
For some reason zbrush by default flips the maps, so I used the “Flip V” option to prevent this.
When connecting the finished Displacement Map to the low-res mesh in Maya, I got an interesting result – the mesh became drastically bloated. This I learned is due to Maya’s interpretation of Displacements from Zbrush. Zbrush interprets black as no change and white to extreme change, while maya interprets black as extreme downward, white extreme upward and gray is no change.
To fix this, I changed the Alpha Gain and Offset settings under the Color Balance tab in the Displacement shader file.
The Specular is done in photoshop using the diffuse as reference.
To export the Texture map from Zbrush, I chose a subtool, and ticked the Clone Texture in the texture map tab. This clones your texture into your texture library, from where you can easily export it into photoshop. I had to merge all the texture maps into one in photoshop as well, like the displacements.
When I had connected all the maps to the mesh in Maya I needed to light the mesh so that the edges fit into the original footage, so that it will be easier to blend in post. It was a great advantage of course to have set up the original lighting for the greenscreen here, because I could just mimic the studio lighting in maya, to get decent results. The lighting becomes somewhat worse when the actor moves further away from the camera, this light was hard to mimic, which was something I had not thought about. I used 3 point lights and 2 area lights to mimic the studio setup.