Publication Type

Conference Proceeding Article

Version

acceptedVersion

Publication Date

10-2009

Abstract

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-ofthe-art STIP based algorithm.

Keywords

Human action recognition, Keypoint trajectory, Mean-shift clustering, Motion subspace learning, Realistic videos

Discipline

Artificial Intelligence and Robotics | Graphics and Human Computer Interfaces

Research Areas

Intelligent Systems and Optimization

Publication

Proceedings of the 17th ACM International Conference on Multimedia, MM'09, Beijing China, 2009 October 19-24

First Page

505

Last Page

508

ISBN

9781605586083

Identifier

10.1145/1631272.1631342

Publisher

ACM

City or Country

Beijing, China

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