With virtual cutting operation for volume data of medical images or reconstructed geometry models from medical images

inside tissues can be observed easily

which can aid doctors to diagnose. The methods can also been used in surgery planning of radiotherapy. In this paper

new methods of plane cutting

stereo clipping and arbitrary cutting operations of 3D surface model reconstructed from medical images are presented. In plane cutting and stereo clipping methods

the 3D model is cut by plane or polyhedron. Lists of edge and vertex in every cut plane are established. From these lists the boundary contours are created and their embracing relationship is built. The region enclosed by the contours is triangulated using Delaunay triangulation algorithm. The procedure of arbitrary cutting operation is to create cutting path interactively at first

then build cutting boundary

and finally cut the model with the boundary. The cut model still maintains its correct topology structure. Experiments show the efficiency and stability of the methods. Good results are achieved by using the methods to cut models reconstructed from medical images.