thinking um
remove objects, select objects
basically vtk provides for this stuff 0321
a vtkPolyData can convert a point to cells using GetPointCells(vtkIdType ptId, vtkIdList* cellIds)
    call BuildLinks() first
        GetPointCells(ptId, vtkIdType& ncells, vtkIdType*& cells)
change poly data:
        - SetPolys(vtkCellArray*) / SetStrips
        - vtkCellArray* GetPolys() / GetStrips
            GetNumberOf...Verts Lines Polys Strips
        vtkIdType InsertNextCell(type, npts, pts[]) type:VTK_POLY_VERTEX, VTK_TRIANGLE, VTK_QUAD, VTK_POLYGON, VTK_TRIANGLE_STRIP
            likely depends on PolyData::Allocate() properties
    BuildCells() NeedToBuildCells returns whether BuildCells has been called DeleteCells() resets, call if you want a new BuildLinks() with new data
    BuildLinks() for topologically complex queries DeleteLinks()
    DeleteCell(cellId) DeletePoint(ptId) RemoveDeletedCells() to compact after
    RemoveGhostCells() removes cells with vtkDataSetAttributes::DUPLICATECELL or ::HIDDENCELL but not their points
traversal (needs BuildLinks):
    GetCellEdgeNeighbors(vtkIdType cellId, vtkIdType p1, vtkIdType p2, vtkIdList* cellIds);
        other useful topological queries

ok um
can we hide something when it is clicked.
- find the clicked triangle
- remove it by hiding it, likely similar to mesh refinement

vtk is big ...

    it's time to sleep. we did find 3dslicer.
    

maybe take the existing viewer
and let the user click on a surface
and then isolate that surface.
so step one would be adding the cell picker.
then step two could be stepping neighbor cells and adding them to a list
then step three could be deleting all other cells and updating the mesh.

the interface could prompt the user what to do:
1. click on your head
2. click on your inion
etc

    but it's time to sleep now.
 we also found https://github.com/Slicer/Slicer
it's called '3D Slicer' and it's used in a reconstruction resource we found
it's a mainstream imagery viewer supporting plugins