Fig. 1. Flowchart of proposed algorithm

Fig. 2. The formation of nested elliptical spatio-temporal tubes

Fig. 3. Spatio-temporal plane maps of nested elliptical spatio-temporal tubes

Fig. 4. Schematic diagram of sub-sampling lines and spatio-temporal flow

Fig. 5. Spatio-temporal flow of video1

Fig. 6. The part of the video frames at spatio-temporal flow curve changed of video1

Fig. 7. Spatio-temporal flow analysis chart of video19