Isovolume and Clip Filters Appears to Convert VTK_POLY_LINES to VTK_LINES
given a single streamline
tetrahedralize will break line into line segments and return a vtkUnstructuredGrid --The number of cells has increased to the number of line segments
Clip appears to break line into segments then clip -- returns many more cells
d3 and append datasets will return that line as an ustructured grid --The number of cells will remain the same
I believe the behavior of Isovolume and Clip should be to preserve the poly line and simply clip that. I believe the current behavior is incorrect.
This is a problem when working with polylines produced from streamline filter.
Workarounds include not using these filters until the very end of the pipeline, but perhaps the filters should be behave as one would expect?