Is there any way to convert an unstructured mesh into an ‘outer surface’ only? I have tried all sorts of combinations of ‘Extract Surface’ and ‘Clean’/’Clean to Grid’ etc.. but I can’t get it to work. Basically I just want to create a mathematical union of all the cells, and where they are adjacent to any other cells they would be considered to be part of the same volume, i.e. a single volume that represents the outer surface of the entire dataset. I suspect it being an unstructured mesh is causing problems here.
ExtractSurface
they would be considered to be part of the same volume
I’m not following, a volume cannot be a surface.
ExtractSurface doesn’t seem to work here. The internal faces all remain (hard to see on a static image, but you can just about make it out here):
“I’m not following, a volume cannot be a surface.” I’m not sure if we use slightly different terminology here, but ‘cell’ to me is a 3D shape, which has a volume defined by the location of it’s outer surface. I just want all the cells combined into a single object, only preserving the outermost surface of the union of all those cells.
I’ve uploaded the .vtu file.
test.vtu (7.7 MB)
Thanks for sharing your data file. We understand “cell” the same way.
The challenge with your data is that it is “cell soup”. Adjacent cells aren’t defined by common points. To extract an outer surface, ParaView uses cell adjacency information where the assumption is that your cells in the volume mostly have adjacent cells that share a face - those faces that don’t have a cell on the other side of are considered boundary faces and that’s what Extract Surfaces extracts.
Because your cells don’t share faces with any other cells - that I can see at least - this approach fails. All faces are considered boundary faces because they have no cell on the other side. That explains what you showed in the image you shared. Below shows how the cells are offset from each other and don’t share faces.
You have a perfectly valid unstructured grid file, but I’m not sure how to identify the non-boundary surfaces in it for display in ParaView.
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