Reply To: Can I select a specific meterial number lattice to output the vtk file ?
I am not sure what you mean. How are you visualizing what in paraview?
In general lattice data is exported block-wise to VTK – the inactive cells present in those blocks are the same that are also inactive in the simulation. If you want to reduce them you need to increase the number of blocks (although whether this has any performance (dis)advantage depends on the specific situation and requires benchmarking to evaluate).