OpenLB – Open Source Lattice Boltzmann Code › Forums › on OpenLB › General Topics › Voxel Image of Arbitrary Geometries › Reply To: Voxel Image of Arbitrary Geometries February 9, 2022 at 9:28 pm #6332 AdrianKeymaster You can load STL files using the STLreader indicator and use it to set material numbers. These material numbers may then be exported to VTK files (see the getResults function for timestep 0 in any of our examples for this part).