Documentation/4.8/Developers/Tutorials/ExportToMaya

Python code to capture the contents of the 3D View and export to an OBJ file called tracts

   exporter = vtk.vtkOBJExporter()
   exporter.SetFilePrefix('/tmp/tracts')
   layoutManager = slicer.app.layoutManager()
   view = layoutManager.threeDWidget(0).threeDView()
   exporter.SetRenderWindow(view.renderWindow())
   exporter.Write()

This code created two files tracts.obj and tracts.mtl which are available in OBJtracts.tar.