"Buesing, Henrik" <hbues...@eonerc.rwth-aachen.de> writes: >> >> > I have structured cell-centered data and would like to visualize >> >> > this with >> >> Paraview. Up to now I use PetscViewerVTKOpen and VecView to write >> >> data in *.vts format. I would like to tell PETSc that the fieldtype >> >> is PETSC_VTK_CELL_FIELD. I have found PetscViewerVTKAddField. >> >> > >> >> > Is this the way to go? I was thinking maybe a DMDASetFieldType >> >> > exists, but >> >> did not find any. If yes, what is the PetscViewerVTKWriteFunction I >> >> need to provide? >> >> >> >> DMDA does not explicitly support distinguishing between cell and >> >> point values. PetscViewerVTKAddField is a developer level routine >> >> and you would need to implement a function similar to >> >> DMDAVTKWriteAll_VTS (not at all trivial and you need to read the code >> >> because it is responsible for almost everything). >> > >> > I am looking at src/sys/classes/viewer/impls/vtk/vtkv.c. There is a >> reference to PETSC_VTK_POINT_FIELD vs. PETSC_VTK_CELL_FIELD. Judging >> from the output I get, I was assuming fieldtype=PETSC_VTK_POINT_FIELD. I >> would be totally fine with replacing POINT by CELL everywhere, since all my >> data is cell-centered. >> >> I think coordinates need to be PointData, not coordinates of cell centroids. >> DMDA doesn't have that concept. (Maybe it should, but adding it is no small >> task and hacking the output is likely to create a lot of edge cases.) >> > I had a look at DMDAVTKWriteAll_VTS. You are totally right that this > is not generic. www.vtk.org/VTK/img/file-formats.pdf describes the > StructuredGrid format. "Points" contain only one DataArray specifying > the coordinates whereas Cells contain three DataArrays with > connectivity, offsets and types.
Are you mixing up CellData from the StructuredGrid XML spec with Cells from the UnstructuredGrid? > What if I use DMDAVTKWriteAll_VTR and write a RectliniearGrid? Then I could > just replace PointData with CellData and "hack" only the extent which should > leave no edge cases... I think it's feasible. You could use DMDAGetInterpolationType() to determine which variant to use.
