Mean Shift, Mode Seeking, and Clustering
IEEE Transactions on Pattern Analysis and Machine Intelligence
IEEE Transactions on Pattern Analysis and Machine Intelligence
Video event detection using motion relativity and visual relatedness
MM '08 Proceedings of the 16th ACM international conference on Multimedia
Space-Time Shapelets for Action Recognition
WMVC '08 Proceedings of the 2008 IEEE Workshop on Motion and video Computing
A Survey of Vision-Based Trajectory Learning and Analysis for Surveillance
IEEE Transactions on Circuits and Systems for Video Technology
A parallel analysis on scale invariant feature transform (SIFT) algorithm
APPT'11 Proceedings of the 9th international conference on Advanced parallel processing technologies
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This paper presents a novel motion localization approach for recognizing actions and events in real videos. Examples include StandUp and Kiss in Hollywood movies. The challenge can be attributed to the large visual and motion variations imposed by realistic action poses. Previous works mainly focus on learning from descriptors of cuboids around space time interest points (STIP) to characterize actions. The size, shape and space-time position of cuboids are fixed without considering the underlying motion dynamics. This often results in large set of fragmentized cuboids which fail to capture long-term dynamic properties of realistic actions. This paper proposes the detection of spatio-temporal motion volumes (namely Volume of Interest, VOI) of scale and position adaptive to localize actions. First, motions are described as bags of point trajectories by tracking keypoints along the time dimension. VOIs are then adaptively extracted by clustering trajectory on the motion mainfold. The resulting VOIs, of varying scales and centering at arbitrary positions depending on motion dynamics, are eventually described by SIFT and 3D gradient features for action recognition. Comparing with fixed-size cuboids, VOI allows comprehensive modeling of long-term motion and shows better capability in capturing contextual information associated with motion dynamics. Experiments on a realistic Hollywood movie dataset show that the proposed approach can achieve 20\% relative improvement compared to the state-of-the-art STIP based algorithm.