Splitted contour surface #19079
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I am visualizing a contour surface of a function, which is stored at cell center of 3D unstructured mesh. Because of parallel computation based on domain decomposition, the computational domain consists of multiple data files (pvtu). If a contour surface crosses a boundary between decomposed domains, the surface is splitted as shown in the attached figure. Is there any approach to avoid this issue? (In Paraview, one can use Filter:clean to Grid) |
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I'd bet Paraview is using the mesh coordinate data to do the clean operation. In general, using mesh coordinates can be unreliable because different processors do not necessarily guarantee that the logically identical node on different processors has the numerically identical coordinate values. There is often some minor numerical differences which then makes judging whether a given node that is duplicated across processor boundaries is intended to be the same logical node or not more guesswork than algorithmic. In VisIt, we require explicit information from the data producer for this. It can take the form of either ghost nodes or zones (or, see vtk ghost nodes or zones) or global node and/or zone ids (an integer field on the nodes or zones that assigns a globally unique id to nodes (or zones) in such a way that the same node (or zone) on different processors gets the same id). So, your choices are to have the data producer write the extra (ghost) data from each processor or define the global ids and include that in the files. |
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Dear Mark, |
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I'd bet Paraview is using the mesh coordinate data to do the clean operation. In general, using mesh coordinates can be unreliable because different processors do not necessarily guarantee that the logically identical node on different processors has the numerically identical coordinate values. There is often some minor numerical differences which then makes judging whether a given node that is duplicated across processor boundaries is intended to be the same logical node or not more guesswork than algorithmic.
In VisIt, we require explicit information from the data producer for this. It can take the form of either ghost nodes or zones (or, see vtk ghost nodes or zones) or global node and…