Gencai Chen

EmoPlayer: A media player for video clips with affective annotations

The development of multimedia annotation technique provides the possibility to redesign the interfaces of widely used media players, and EmoPlayer is such a media player that can be used to play video clips with affective annotations. A user can select a character in a video clip and view the distribution of his/her emotions along the video timeline through a colour bar based interface. Two experiments were conducted to evaluate the efficiency of affective annotation. The results of these experiments indicate that affective annotation is effective in both improving the speed of locating a specific scene within a video clip and helping comprehend a video clip in a limited viewing time period. Based on the analysis of recorded operations of participants, the strategies employed by participants and the factors that might influence the utilization of affective annotation are also highlighted.

Large head movement tracking using sift-based registration

Although there exists dozens of vision based 3D head tracking methods, none of them considers the problem of large motion, especially the movement along the Z axis. In this paper we propose a novel tracking method to handle this problem by using Scale Invariant Feature Transform (SIFT) based registration algorithm. Salient SIFT features are first detected and tracked between two images, and then the 3D points corresponding to these features are obtained from a stereo camera. With these 3D points, a registration algorithm in a RANSAC framework is employed to detect the outliers and estimate the head pose. Performance evaluation shows an accurate pose recovery (3° RMS) when the head has large motion, even with movement along the Z axis was about 150 cm.

Continuous visible nearest neighbor query processing in spatial databases

In this paper, we identify and solve a new type of spatial queries, called continuous visible nearest neighbor (CVNN) search. Given a data set P, an obstacle set O, and a query line segment q in a two-dimensional space, a CVNN query returns a set of

Visible Reverse k-Nearest Neighbor Query Processing in Spatial Databases

{langle p, Rrangle}

Visible Reverse k-Nearest Neighbor Queries

tuples such that

KPB-SIFT: a compact local feature descriptor

{p in P}