FBVA: A Flow-Based Visual Analytics Approach for Citywide Crowd Mobility

Analyzing structures of crowd mobility at city level is a challenging task due to the complex crowd mobility and dynamic changes generated by the social activities over time. These structures, defined as high-dimensional mobility structures (HMSs), contain spatiotemporal information and are simultaneously influenced by the geographical distributions and daily activities of citywide crowd. However, few work has been dedicated to depict and analyze these structures, mainly due to the lack of effective models. In this paper, we propose to model the crowd mobility as a dynamical system and characterize the irregular mobility data with a novel local coherence of sparse field (LCSF) algorithm. The proposed algorithm makes it possible to measure the separation behavior of trajectories in an irregular and sparse topology network. Detected HMS, referred as local separation measure of LCSF, divides the geographical urban areas into distinct functional regions over time. We design and implement a visual analytics system to facilitate situation-aware analysis of a huge amount of crowd mobility and their socialized behaviors. Case studies based on a real-world data set demonstrate the effectiveness of the proposed approach.