10 research outputs found
A graphical simulator for modeling complex crowd behaviors
Abnormal crowd behaviors of varied real-world settings could represent or pose serious threat to public safety. The video data required for relevant analysis are often difficult to acquire due to security, privacy and data protection issues. Without large amounts of realistic crowd data, it is difficult to develop and verify crowd behavioral models, event detection techniques, and corresponding test and evaluations. This paper presented a synthetic method for generating crowd movements and tendency based on existing social and behavioral studies. Graph and tree searching algorithms as well as game engine-enabled techniques have been adopted in the study. The main outcomes of this research include a categorization model for entity-based behaviors following a linear aggregation approach; and the construction of an innovative agent-based pipeline for the synthesis of A-Star path-finding algorithm and an enhanced Social Force Model. A Spatial-Temporal Texture (STT) technique has been adopted for the evaluation of the model's effectiveness. Tests have highlighted the visual similarities between STTs extracted from the simulations and their counterparts - video recordings - from the real-world
Crowd Saliency Detection via Global Similarity Structure
It is common for CCTV operators to overlook inter- esting events taking place
within the crowd due to large number of people in the crowded scene (i.e.
marathon, rally). Thus, there is a dire need to automate the detection of
salient crowd regions acquiring immediate attention for a more effective and
proactive surveillance. This paper proposes a novel framework to identify and
localize salient regions in a crowd scene, by transforming low-level features
extracted from crowd motion field into a global similarity structure. The
global similarity structure representation allows the discovery of the
intrinsic manifold of the motion dynamics, which could not be captured by the
low-level representation. Ranking is then performed on the global similarity
structure to identify a set of extrema. The proposed approach is unsupervised
so learning stage is eliminated. Experimental results on public datasets
demonstrates the effectiveness of exploiting such extrema in identifying
salient regions in various crowd scenarios that exhibit crowding, local
irregular motion, and unique motion areas such as sources and sinks.Comment: Accepted in ICPR 2014 (Oral). Mei Kuan Lim and Ven Jyn Kok share
equal contribution
Socially Constrained Structural Learning for Groups Detection in Crowd
Modern crowd theories agree that collective behavior is the result of the
underlying interactions among small groups of individuals. In this work, we
propose a novel algorithm for detecting social groups in crowds by means of a
Correlation Clustering procedure on people trajectories. The affinity between
crowd members is learned through an online formulation of the Structural SVM
framework and a set of specifically designed features characterizing both their
physical and social identity, inspired by Proxemic theory, Granger causality,
DTW and Heat-maps. To adhere to sociological observations, we introduce a loss
function (G-MITRE) able to deal with the complexity of evaluating group
detection performances. We show our algorithm achieves state-of-the-art results
when relying on both ground truth trajectories and tracklets previously
extracted by available detector/tracker systems
Visual Crowd Surveillance Through A Hydrodynamics Lens
Video cameras monitoring the activity of people in public settings are commonplace in cities worldwide. At large events, where crowds of hundreds or thousands gather, such monitoring is important for safety and security purposes but is also extremely (technically) challenging. Human operators are generally employed for the task, but even the most vigilant humans miss important information that could ultimately contribute to unfavorable consequences. Major research efforts are under way to develop systems that cue security personnel to individuals or events of interest in crowded scenes. Essential are methods by which information can be extracted from video data in order to recognize crowd behaviors, track. © 2011 ACM