By looking around, someone pointed me to this old test file that seems to generate what you intend to do: VisualizeLagrangeTriangleMesh.cc (9.4 KB)
It might be vtkDataSetSurfaceFilter which does the trick, but I didn’t test enough to figure out exactly where the magic happens.
Here is a screen of the result rendered in ParaView:
I hope you figure out how to apply this example to your setup soon!