hello: i give the threshold (vtkImageThreshold) a imageData whoes extent is (0,63,0,63,0,92) ,but the extent of threshold->GetOuput() is (0,63,0,63,45,49)， vtkImageThreshold changed the extent ! what is the problem? thanks for helping me. jiang-gx jxjx at sjtu.edu.cn 2004-12-08