They are indeed 3D cells. The mesh is hexa-dominant, simulation results are cell data, interpolated in VTK to point data. The values of the field where I am doing the scalar clip, follow a bimodal distribution where the majority of the values are either 0 or 1. There are a few intermediate values at the interface between between 0 and 1 cells, in this specific case more than I am used to get, which is why the clips are of poor quality. Usually I get very well triangulated surfaces after the clip.
Thanks, good to know. I’ll take it into account next time I’m debugging VTK issues