Currently, the Exodus reader creates polydata for side and node sets. This makes it hard for ParaView to allow editing of node+side sets; and hard for writers to know what is geometry is really just coincident vs what is intended to be a reference to other geometry.
I would like (eventually, not in the short term) for the MED and ExodusII readers to create vtkSelection data objects for side and node sets. There are 2 obstacles I see to doing this:
It would require extending vtkSelectionNode::SelectionField to include a new enumerant (CELL_SIDE or CELL_BOUNDARY) to deal with side sets since they typically refer to a lower-dimensional boundary of the original cell.
It might change how we want to render vtkSelection objects. (I don’t know if they are handled by mappers at all directly but suspect not… there would probably need to be changes to either mappers or representations to deal with them.)
Do any of you have objections? Better ideas?