Crowd simulation using DC model and density information

Realistic crowd simulation is an important issue for the production of virtual worlds for games, crowd management, public space design, education, entertainment or architectural and urban planning. In this paper, crowd simulation is considered from two aspects: intra-group simulation and inter-group simulation. We propose a unified framework for crowd simulation in real-time virtual environment. Based on this framework, for intra-group simulation, we propose a novel density-based information crowd simulation to collision-free. For inter-group simulation, we propose a novel discrete choice (DC) model to realistic simulation of crowds and path planning. Meanwhile, we also propose a variable bounding box method for intra-group/inter-groups intersection problem. The simulation results show that the developed framework allows different group structures to be easily modeled. And the proposed framework could be used for real-time navigation of many moving crowd in complicated virtual environments.     

群体动力学的群组行为仿真

目的 许多群体动画算法侧重从宏观或微观角度模拟人群运动,而结合两种方法模拟群组动态的算法较少,为解决这个问题,提出一种基于群体动力学的群组行为仿真算法。方法 首先,采用连续模型构建动态势能场,为个体计算运动初始速度;然后,基于群体动力学模拟组内跟随和组间避让行为;在组内跟随行为中采用“Car-following”模型为个体计算跟随加速度;在组间避让行为中提出群组的凸包表示方法,并引入局部势能场;最后,结合动态势能场和局部势能场实现群组行为仿真。结果 在每个仿真循环中动态更新全局势能场信息,对比不同群体规模及网格精度的人群仿真效率。实验结果表明本文算法能用于模拟规模较大的多样性群组运动。在网格分辨率为80×80像素的场景中对5 000个个体的运动进行仿真,平均帧速率为35.7 ms（约28帧/s）,与传统的连续模型相比产生了更多的群组行为。采用快速行进法构建全局动态势能场,即使在粗糙网格中也能得到较为平滑的路径。结论 提出算法适用于多样性群组行为仿真,同时结合全局规划和局部控制,无需额外碰撞检测便能真实地模拟组内跟随和组间避让行为,仿真效果具有高效性和多样性。     

Spice: a cognitive agent framework for computational crowd simulations in complex environments

Pedestrian behavior is an omnipresent topic, but the underlying cognitive processes and the various influences on movement behavior are still not fully understood. Nonetheless, computational simulations that predict crowd behavior are essential for safety, economics, and transport. Contemporary approaches of pedestrian behavior modeling focus strongly on the movement aspects and seldom address the rich body of research from cognitive science. Similarly, general purpose cognitive architectures are not suitable for agents that can move in spatial domains because they do not consider the profound findings of pedestrian dynamics research. Thus, multi-agent simulations of crowd behavior that strongly incorporate both research domains have not yet been fully realized. Here, we propose the cognitive agent framework Spice. The framework provides an approach to structure pedestrian agent models by integrating concepts of pedestrian dynamics and cognition. Further, we provide a model that implements the framework. The model solves spatial sequential choice problems in sufficient detail, including movement and cognition aspects. We apply the model in a computer simulation and validate the Spice approach by means of data from an uncontrolled field study. The Spice framework is an important starting point for further research, as we believe that fostering interdisciplinary modeling approaches will be highly beneficial to the field of pedestrian dynamics.     

Crowds by Example

We present an example-based crowd simulation technique. Most crowd simulation techniques assume that the behavior exhibited by each person in the crowd can be defined by a restricted set of rules. This assumption limits the behavioral complexity of the simulated agents. By learning from real-world examples, our autonomous agents display complex natural behaviors that are often missing in crowd simulations. Examples are created from tracked video segments of real pedestrian crowds. During a simulation, autonomous agents search for examples that closely match the situation that they are facing. Trajectories taken by real people in similar situations, are copied to the simulated agents, resulting in seemingly natural behaviors.     

Right of way

Pedestrian models typically represent interactions between agents in a symmetric fashion. In general, these symmetric relationships are valid for a large number of crowd simulation scenarios. However, there are many cases in which symmetric responses between agents are inappropriate, leading to unrealistic behavior or undesirable simulation artifacts. We present a novel formulation, called right of way, which provides a well-disciplined mechanism for modeling asymmetric relationships between pedestrians. Right of way is a general principle, which can be applied to different types of pedestrian models. We illustrate this by applying right of way to three different pedestrian models (two based on social forces and one based on velocity obstacles) and show its impact in multiple scenarios. Particularly, we show how it enables simulation of the complex relationships exhibited by pilgrims performing the Islamic religious ritual, the Tawaf.     

SITUATED CELLULAR AGENTS APPROACH TO CROWD MODELING AND SIMULATION

The article describes a multi-agent approach to crowd modeling and simulation. After a brief introduction of the Situated Cellular Agents model, the guidelines to the crowd modeling approach is introduced as a way to support the communication among the different actors that are part of the simulation project team. The approach is then applied to describe a complex scenario providing a blend of competitive and cooperative behavior for pedestrian agents: an underground station. A module supporting the effective 3D visualization of simulated crowd dynamics is finally introduced, as an instrument for the communication of simulation results to decision makers and nonexperts in crowd phenomena.     

Crowd Simulation and Its Applications: Recent Advances

This article surveys the state-of-the-art crowd simulation techniques and their selected applications, with its focus on our recent research advances in this rapidly growing research field. We first give a categorized overview on the mainstream methodologies of crowd simulation. Then, we describe our recent research advances on crowd evacuation,pedestrian crowds, crowd formation, traffic simulation, and swarm simulation. Finally, we offer our viewpoints on open crowd simulation research challenges and point out potential future directions in this field.     

Context‐Dependent Crowd Evaluation

Many times, even if a crowd simulation looks good in general, there could be some specific individual behaviors which do not seem correct. Spotting such problems manually can become tedious, but ignoring them may harm the simulation's credibility. In this paper we present a data‐driven approach for evaluating the behaviors of individuals within a simulated crowd. Based on video‐footage of a real crowd, a database of behavior examples is generated. Given a simulation of a crowd, an analog analysis is performed on it, defining a set of queries, which are matched by a similarity function to the database examples. The results offer a possible objective answer to the question of how similar are the simulated individual behaviors to real observed behaviors. Moreover, by changing the video input one can change the context of evaluation. We show several examples of evaluating simulated crowds produced using different techniques and comprising of dense crowds, sparse crowds and flocks.     

Generation and use of sparse navigation graphs for microscopic pedestrian simulation models

For the spatial design of buildings as well as for the layout of large event areas, the crowd behaviour of the future users plays a significant role. The designing engineer has to make sure that potentially critical situations, such as high densities in pedestrian crowds, are avoided in order to guarantee the integrity, safety and comfort of the users. To this end, computational pedestrian dynamics simulations have been developed and are increasingly used in practice. However, most of the available simulation systems rely on rather simple pedestrian navigation models, which reflect human behaviour only in a limited manner. This paper contributes to enhancing pedestrian simulation models by extending a microscopic model by a navigation graph layer serving as a basis for different routing algorithms. The paper presents an advanced method for the automated generation of a spatially embedded graph which is on the one hand as sparse as possible and on the other hand detailed enough to be able to serve as a navigation basis. Three different pedestrian types were modelled: pedestrians with good local knowledge, pedestrians with partly local knowledge and those without any local knowledge. The corresponding algorithms are discussed in detail. To illustrate how this approach improves on simulation results, an example scenario is presented to demonstrate the difference between results with and without using a graph as constructed here. Another example shows the application of the extended simulation in a real-world engineering context. The article concludes with an outlook of further potential application areas for such navigation graphs.     

考虑分类人群行为的建筑疏散模型研究

人员行为决定了应急疏散时人群的时空分布,是研究疏散动力学的关键。考虑疏散时人员的心理特性与身份状态,将人群分为恐慌人群、易感人群、冷静人群和管理人群四类,基于社会力模型表达各类人群的疏散行为特征,并开展不同情境的疏散动力学过程分析。研究发现行人的恐慌心理具有传播作用,对其他行人的疏散行为有明显的影响,而管理人员的引导作用对疏散有积极影响,当其比例在10%~15%的时候效果显著,且合适的位置更易提高疏散效率;人员的服从水平越大,疏散效率越高。提出的分类人群疏散行为模型能为建筑安全疏散评估与优化提供理论支持。     

基于ACP的动态网民群体运动组织建模与计算实验研究

由互联网促成的社会运动组织一经出现, 就受到了广大社会学者以及计算机领域专家的广泛关注. 一方面, 互联网特别是移动互联网在整合信息、引发共振、实时分享及高度互动等方面的特性, 为网民行为的大规模快速聚集提供了直通渠道, 使得多角度超视距观察并研究在线人群复杂行为及其组织特性成为可能; 另一方面, 这一研究在社会化媒体营销、共享经济、非军事组织行动中的应用意义愈加显著. 本文引入群体行为动力学和社会运动组织理论的研究, 提出基于ACP的动态网民群体运动组织(Cyber movement organizations, CMOs)研究方法. 本文工作首先使用多智能体建模方法构造双层结构的人工社区模型, 以此为基础对动态网民的个体以及群体动态组织行为展开计算实验探讨, 重点阐释了社区用户的交互行为机制及群体组织活动的建模机制, 为揭示微观个体简单行为对于宏观群体复杂涌现现象的影响奠定基础.     

Crowd simulation for emergency response using BDI agents based on immersive virtual reality

This paper presents a novel methodology involving a Virtual Reality (VR)-based Belief, Desire, and Intention (BDI) software agent to construct crowd simulation and demonstrates the use of the same for crowd evacuation management under terrorist bomb attacks in public areas. The proposed BDI agent framework allows modeling of human behavior with a high degree of fidelity. The realistic attributes that govern the BDI characteristics of the agent are reverse-engineered by conducting human-in-the-loop experiments in the VR-based Cave Automatic Virtual Environment (CAVE). To enhance generality and interoperability of the proposed crowd simulation modeling scheme, input data models have been developed to define environment attributes (e.g., maps, demographics, evacuation management parameters). The validity of the proposed data models are tested with two different evacuation scenarios. Finally, experiments are conducted to demonstrate the effect of various crowd evacuation management parameters on the key performance indicators in the evacuation scenario such as crowd evacuation rate and densities. The results reveal that constructed simulation can be used as an effective emergency management tool.     

视觉信息在行人群体仿真中的应用

传统群体仿真技术常把群体看成若干个体的组合,但事实上群体是由若干具有相似行为的个体组成的群组所构成的.针对大多数现有群体仿真技术由于没有考虑到上述因素,导致仿真结果和真实生活中的群体行为存在一定差异的问题,并结合群体是由不同小群组构成的特点,提出一种基于视觉信息指导并考虑行人动态寻路和局部碰撞避免的方法.仿真结果显示,该方法在仿真群体时能够获得较为自然的自组织现象,与现有的几种方法相比,这种现象在复杂环境或者高密度情况下会更加明显.     

Learning behavior patterns from video for agent-based crowd modeling and simulation

This paper proposes a novel data-driven modeling framework to construct agent-based crowd model based on real-world video data. The constructed crowd model can generate crowd behaviors that match those observed in the video and can be used to predict trajectories of pedestrians in the same scenario. In the proposed framework, a dual-layer architecture is proposed to model crowd behaviors. The bottom layer models the microscopic collision avoidance behaviors, while the top layer models the macroscopic crowd behaviors such as the goal selection patterns and the path navigation patterns. An automatic learning algorithm is proposed to learn behavior patterns from video data. The learned behavior patterns are then integrated into the dual-layer architecture to generate realistic crowd behaviors. To validate its effectiveness, the proposed framework is applied to two different real world scenarios. The simulation results demonstrate that the proposed framework can generate crowd behaviors similar to those observed in the videos in terms of crowd density distribution. In addition, the proposed framework can also offer promising performance on predicting the trajectories of pedestrians.     

Workload balancing in distributed crowd simulations: the partitioning method

The simulation of large crowds of autonomous agents with a realistic behavior is still a challenge for several computer research communities. Distributed architectures can provide scalability to crowd simulations, but they require the use of efficient partitioning methods. Although convex hulls have been shown as very efficient structures for crowd partitioning, providing efficient workload balancing to large scale simulations is still an open issue. In this paper, we propose the integration of a workload balancing technique for crowd simulations within a partitioning method based on convex hulls. The region-based balancing technique reassigns agents to servers using a criterion of distance. The performance evaluation results show that this technique ensures the saturation avoidance of the servers in an homogeneous distributed system. This feature can increase the scalability of crowd simulations.     

战术通信中异构Ad-hoc网络路由策略

针对战术通信中的网络异构性和节点群组移动性,在建立群组移动模型的基础上,采用簇头稳定分簇算法动态划分管理异构网络分层结构,提出基于链路状态的分层路由策略整合异构无线资源。该策略分为区内路由策略和区间路由策略,面向不同网络层次采用不同路由机制。OPNET仿真结果表明,该策略的分组成功接收率和平均端到端延时性能均优于分层AODV协议。     

遗传算法与行人疏散模型结合的建筑出口优化

构建基于遗传算法与行人运动仿真模型的双层优化框架，选取单室双出口场景，考虑两个出口在同一侧、相邻侧、相对侧3种典型布局，设定3种人员身形，3种疏散初始人群密度，9种疏散出口大小条件，形成243个数值实验场景，分别计算获得最有利于人员疏散的出口布局。研究发现疏散出口宽度与疏散效率呈正向关系，疏散人员半径、初始人员密度与疏散效率呈负向关系，同时在不同布局中，影响疏散效率的关键参数有一定区别。     

融入情绪模型的人群实时路径规划

目的 人群仿真中高效性和逼真性是群体路径规划的关键问题。已有人群路径规划算法忽略了人群情绪造成的路径选择差异,在大规模实时仿真中仍存在一定的局限性。方法 提出一种融入情绪模型的人群实时路径规划算法(EPP)。使用人格特征理论对人群的情绪进行建模并设定不同情绪所具有的路径选择偏好。在路径建模阶段,通过单次搜索建立全局有向导航图,确定全局层面的可行路径;在路径搜索阶段,提出以期望时间最短为原则的路径规划目标函数,采用局部搜索策略为个体实时规划一条最优或次优的路径。结果 EPP算法可有效地仿真不同场景下大规模人群的路径选择现象;与已有工作的仿真效果和量化指标对比说明了该算法的有效性和高效性;通过不同情绪状态下人群路径选择差异的讨论以及在不同人群运动模型的兼容性实验进一步说明了该算法的健壮性。结论 本文算法具有良好的高效性和健壮性,适用于不同场景下大规模人群路径规划的相关应用。     

Vision-based analysis of small groups in pedestrian crowds

Building upon state-of-the-art algorithms for pedestrian detection and multi-object tracking, and inspired by sociological models of human collective behavior, we automatically detect small groups of individuals who are traveling together. These groups are discovered by bottom-up hierarchical clustering using a generalized, symmetric Hausdorff distance defined with respect to pairwise proximity and velocity. We validate our results quantitatively and qualitatively on videos of real-world pedestrian scenes. Where human-coded ground truth is available, we find substantial statistical agreement between our results and the human-perceived small group structure of the crowd. Results from our automated crowd analysis also reveal interesting patterns governing the shape of pedestrian groups. These discoveries complement current research in crowd dynamics, and may provide insights to improve evacuation planning and real-time situation awareness during public disturbances.