3 research outputs found
Exemplar-AMMs: Recognizing Crowd Movements From Pedestrian Trajectories
In this paper, we present a novel method to recognize the types of crowd movement from crowd trajectories using agent-based motion models (AMMs). Our idea is to apply a number of AMMs, referred to as exemplar-AMMs, to describe the crowd movement. Specifically, we propose an optimization framework that filters out the unknown noise in the crowd trajectories and measures their similarity to the exemplar-AMMs to produce a crowd motion feature. We then address our real-world crowd movement recognition problem as a multi-label classification problem. Our experiments show that the proposed feature outperforms the state-of-the-art methods in recognizing both simulated and real-world crowd movements from their trajectories. Finally, we have created a synthetic dataset, SynCrowd, which contains 2D crowd trajectories in various scenarios, generated by various crowd simulators. This dataset can serve as a training set or benchmark for crowd analysis work
Topological Data Analysis of Biological Aggregation Models
We apply tools from topological data analysis to two mathematical models
inspired by biological aggregations such as bird flocks, fish schools, and
insect swarms. Our data consists of numerical simulation output from the models
of Vicsek and D'Orsogna. These models are dynamical systems describing the
movement of agents who interact via alignment, attraction, and/or repulsion.
Each simulation time frame is a point cloud in position-velocity space. We
analyze the topological structure of these point clouds, interpreting the
persistent homology by calculating the first few Betti numbers. These Betti
numbers count connected components, topological circles, and trapped volumes
present in the data. To interpret our results, we introduce a visualization
that displays Betti numbers over simulation time and topological persistence
scale. We compare our topological results to order parameters typically used to
quantify the global behavior of aggregations, such as polarization and angular
momentum. The topological calculations reveal events and structure not captured
by the order parameters.Comment: 25 pages, 12 figures; second version contains typo corrections, minor
textual additions, and a brief discussion of computational complexity; third
version fixes one typo and adds small paragraph about topological stabilit