Marking surface types

PathEngine surface types are marked within maya by assigning special shaders to faces in a mesh.
The shaders must be set up with a 'notes' attribute containing markup to define the surface type value associated with each shader.

Adding a new surface type

Select some faces to which you wish to assign the new surface type.
Right click on these faces and hold, and then select Materials -> Assign New Material -> Lambert.

Rename the new material appropriately (for your own purposes - the exporter doesn't care what name you use), and then add text of the format '{surfaceType=n}' to the notes attribute of this newly created shader, where n is the PathEngine surface type value to associate with this shader.

You can also set the other properties of the shader (e.g. colour) as desired, to help with visualisation of surface types within Maya.

Working with surface type shaders

Once you have creater a surface type shader you can use 'Assign Existing Material' instead of 'Assign New Material'.
Use the hypershade window to browse the set of shaders associated with a scene.