In the new MPEG-4 video coding standard

the semi-automatic video segmentation plays a key role in supporting object-oriented coding and enabling content-based functionalities. A novel hierarchy optical flow based semi-automatic spatial-temporal video segmentation method is presented in this paper. The proposed algorithm comprises of spatial and temporal segmentation modules. In the spatial segmentation stage

the user can input points around the video object(VO) with the proposed point-based graphic user interface(PBGUI)

then active contour model and tracking bug algorithm are used to precisely define the video object of interest to be segmented. With the result of spatial segmentation

the temporal segmentation involves non-rigid object boundary tracking and rigid object whole entity tracking by hierarchy optical flow algorithm based on the algorithm proposed by Lucas and Kanade. And the tracking points selection algorithm is proposed to greatly improve the tracking performance in the rigid object whole entity tracking. The experimental results show that the proposed algorithm can precisely segment video objects from video clips and can be applied to object-oriented coding

content-based functionality and multimedia database indexing.