An Efficient Method of Crowd Aggregation Computation in Public Areas

The crowd stampede and terrorist attacks in public areas have now become more serious and dangerous threats due to the rapid increase in the population and scale of cities. Therefore, the analysis of crowd aggregation behavior has been a new research focus in the field of intelligent video surveillance. However, such public area scenes not only contain moving crowd but also contain other types of objects. The sizes of these objects are usually small, which make their appearances quite similar. Moreover, the individuals in a crowd move randomly and often occlude each other. All the above factors make the analysis of crowd aggregation very difficult. In this paper, the authors attempt to solve this problem in three aspects. First, a novel global feature is used to represent the moving crowd. This feature can well describe the spatial and the temporal motion information of points-of-interest. Second, a strategy is adopted to cluster the feature points first and then calculate the collectiveness. This makes the collectiveness computation of individual groups more consistent and effective. Finally, more comprehensive collective crowd descriptors are proposed to provide a detailed description of the crowd status. Based on the proposed descriptor, the authors realize the evolution analysis of the group movement and the crowd abnormal detection. The experiment results show that the proposed method is able to efficiently compute the crowd collectiveness in various public areas and provide a reliable reference for the public safety management.