Thank you very much for your reply! I have resolved the issue by inheriting from vtkCellPicker and overriding its IntersectActorWithLine. However, I found that when using a large number of blocks (around 8000, each block containing approximately 2500 cells) and trying to update their coordinates, the performance of vtkCompositePolyDataMapper is quite poor. Therefore, I plan to abandon this approach and try a different path. I would greatly appreciate it if anyone could offer a better solution.