Reply To: Extract Lattice data
As for the second question (you may consider opening separate threads for separate questions to keep things easy to follow for other users):
You do not need material indicators for that. I am not completely sure what you want to accomplish. If you only want to get the material data the VTK output included in every example is the most straight forward option.
If you have a lattice position [iC, iX, iY] you can get the material number via e.g. SuperGeometry2D::getBlockGeometry(iC).get(iX, iY).