RESEARCH

View-invariant Recognition of Human Actions

Action Recognition

Recognition of human motion and action is an important area of research in computer vision that plays a crucial role in various applications such as surveillance, human-computer interaction, ergonomics, etc. Depending on the nature and the scale of the problem, understanding of human motion is usually studied at four levels of granularity: pose, movement, action, and activity. The challenges being addressed include perspective distortions, differences in viewpoints, unknown camera parameters, anthropometric variations, and the large degrees of freedom of articulated bodies. Action can be regarded as a collection of 4D space-time data observed by a perspective video camera. After image projection, the 3D Euclidean information is lost and projectively distorted, which makes action recognition rather challenging, especially for varying viewpoints. Another source of challenge is the irregularities of human actions due to a variety of factors such as age, gender, circumstances, etc. The timeline of action is another important issue in action recognition. The execution rates of the same action in different videos may vary due to different actors or variable camera frame rates. Therefore, the mapping between same actions in different videos is usually highly non-linear.

Related papers:

  • Nazim Ashraf, Yuping Shen and Hassan Foroosh, View-Invariant Action Recognition Using Rank Constraint, International Conference on Pattern Recognition (ICPR), to appear, 2010.

  • Yuping Shen, Nazim Ashraf, and Hassan Foroosh, Action Recognition based on Homography Constraints, International Conference on Pattern Recognition (ICPR), 2008. - Best Scientific Paper Award - (PDF)