    structured_grid = vtkStructuredGrid()
    # Specify the dimensions of the grid, set the points and blank one point.
    structured_grid.SetDimensions(grid_size, grid_size, 1)
    structured_grid.SetPoints(points)
    structured_grid.BlankPoint(pt_idx)

--
    geometry_filter = vtkStructuredGridGeometryFilter()
    geometry_filter.SetInputData(structured_grid)

    # Create a mapper and actor.
    grid_mapper = vtkDataSetMapper()
    grid_mapper.SetInputConnection(geometry_filter.GetOutputPort())
--
    sgrid = vtkStructuredGrid()
    sgrid.SetDimensions(dims)

    # We also create the points and vectors. The points
    # form a hemi-cylinder of data.
    vectors = vtkDoubleArray()
