Measurability of Crowd Collectiveness in Dynamic Scenes

Collective motions are common in crowd systems and have attracted a great deal of attention in a variety of multidisciplinary fields [2]. Collectiveness, which indicates the degree of individuals acting as a union in collective motion, is a fundamental and universal measurement for various crowd systems. Quantitatively measuring this universal property and comparing it across different crowd systems are important in order to understand the general principles of various crowd behaviors. It plays important roles in many applications, such as monitoring the transition of a crowd system from disordered to ordered states, studying correlation between collectiveness and other crowd properties such as population density, characterizing the dynamic evolution of collective motion, and comparing the collectiveness of different crowd systems. One remarkable observation of collective motions in various crowd systems is that some spatially coherent structures emerge from the movements of individuals in the crowds, which are referred to as collective manifold of collective motion illustrated in Fig.1. Based on the structure of collective manifold, our work aims at analyzing the measurability of crowd collectiveness and formulating a new collectiveness descriptor for collective motions1.