These are the notes from a tutorial I did in order to to test out whether we could use this method for adding detail to our monster characters in Maya. The idea is to make a low poly mesh in Maya and then generate a normal/displacement map from the sculpted detail in Mudbox which can be brought back to Maya for rendering.
02. Importing and Exporting Geometry
Exporting as an .obj file exports the geometry and UV map etc. .fbx contains more detail. The grid size in Maya and Mudbox don’t match. In Maya, freeze the transformations before exporting. When exporting from Mudbox, check window>preferences and check the settings e.g. fbx blendshape. Then select the object and >export.
03 Importing and exporting texture file
You can export your paint layer by right clicking and exporting maps. If you want to export your paint layers separately, make sure that ‘flatten layers on export’ is turned off in the preferences. Paint the desired layers. Then select the object and export as an fbx. This will automatically set up a layered shader of the different paint layers.
04 Transferring normal and displacement maps.
Go to >maps>texture maps> new operation. A normal map is like a bump map that allows you to work with a low resolution model but makes it appear highly detailed. The target model is the level 0 low resolution in mudbox and the source model is the highest level sculpt. Change the method to subdivision instead of raycasting (as we are working with the same mesh that detail has been added to). Choose ‘tangent based’ for geometry that is going to be deformed. A normal map is only the illusion of detail where as a displacement creates geometry. For exporting displacements – export as a 32bit exr. Plug the file into the displacement of the material. In order for the displacement to work the geometry needs to subdivide at render time. Go into rendering editors>mental ray> approximation editors. Under subdivision hit ‘create’ a new approximation. In the attribute editor > set subdivisions to 03 (for example)
05 Using the’ send to’ features in maya and mudbox.
06 Creating base meshes in maya.
Meshes with topology problems such as non-manifold topology will not be able to subdivide in Mudbox. Try and create an even quad layout.
07 Working with UVs.
You can create UVs in Mudbox from the menu which will break each face up into shapeless coordinates. You can export UVs as an .obj file and select the object in Mudbox and import UVs. You can tile the UVs in Maya/Mudbox also so as to dedicate more resolution to each area. Paint layers are based on the UV layout but sculpt layers are not. You can however transfer paint layers from bad UVs onto good UVs for example.
08 Modifying and updating topology.
Sometimes as we sculpt, the flow of topology on the original mesh may not match up with our sculpted result. Reroute the topology to match the detail.
09 Adding New Pieces of Geometry
Send your geometry from mudbox over to maya as a guide for adding new geometry around it.
10 Importing Joints and Weighting
A rig set up in Maya can be imported along with the model. The rig is accessed in Mudbox through the ‘pose tools’ tray along the bottom. A model can be exported as an .fbx – make sure the ‘import rig’ option is ticked in the preferences for .fbx.