vtkPolyDataConnectivityFilter treats seeded regions as one
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
I think I found a bug in vtkPolyDataConnectivityFilter, or at least misleading documentation.
The Documentation for mode 4 says "4) extract all regions sharing specified cell ids;" To me this means that the list of seed IDs will be used to seed different regions. GetNumberOfExtractedRegions should give me the number of seeds, and the regions should be colored differently if SetColorRegions is on. This is not what happens. Instead GetNumberOfExtractedRegions returns 1, and all the regions are given the same region number.
After looking at Graphics/vtkPolyDataConnectivityFilter.cxx I see the comment on line 202, "regions have been seeded, everything considered in same region" So I think it's the documentation that is wrong, for the simple reason that it's easier to fix. A second connectivity filter with SetExtractionModeToAllRegions will get what I want.
I think a solution would be a line in the documentation that seeded regions will all be considered to have the same ID but a seccond connectivity filter can then add the abilities of extract all regions.