Jakub Porzycki

Cellular Automata as the basis of effective and realistic agent-based models of crowd behavior

The Cellular Automata (CA) paradigm has been recognized as an effective approach used in the modeling and simulation of complex systems. However, its classical form of a homogeneous and synchronous CA has a limited field of applications. For practical applications, non-homogeneous and asynchronous CAs with hybrid technological construction are especially useful in modeling and simulation. In this article, the authors focus on crowd simulations based on CA and agent-based modeling approaches. Basic technical aspects of large-scale crowd simulations are presented: specifically proposed architecture, our view on synchronization patterns, as well as hierarchy of objects in logic and data layer. A new method of agent conflict resolution is also proposed. Such an approach was successfully applied in the Allianz Arena stadium model, and other large-scale simulations developed by the authors. Thus, finally, practical applications of the models are presented.

Dynamic Data–Driven Simulation of Pedestrian Movement with Automatic Validation

The article presents a dynamic data-driven simulation of pedestrian movement based on the generalized Social Distances Model, where a simulation system is continuously synchronized with current flow data, gained from Microsoft Kinect depth map. Both simulation and data analysis are real-time processes. Agent appears in simulation, as soon as consecutive pedestrians leave sensors tracking zone. Due to system architecture containing feedback loop, automatic validation and parameters calibration is possible. A new method of depth map based pedestrian tracking is proposed as well as a new algorithm of pedestrian parameters extraction for short trajectories. The paper describes in detail the proposed algorithms, system architecture and an illustrative experiment.

Three Different Approaches in Pedestrian Dynamics Modeling – A Case Study

In this work different approaches to crowd dynamics modeling are compared in terms of efficiency and accuracy. The authors analyze and test applicability of some characteristic microscopic models including: Generalized Centrifugal Force Model, Social Distances, as well as macroscopic model represented by hydrodynamic approach. Models were compared on a real life test case, for which precise empirical results were obtained, to find sufficient balance between dependability of results and computational effort.

Application of NIST Technical Note 1822 to CA Crowd Dynamics Models Verification and Validation

This paper addresses the issue of application of methodology included in NIST technical note 1822: The Process of Verification and Validation of Building Fire Evacuation Models [1] in terms of CA crowd dynamics models. The note is a recently released document (November 2013), that proposes a set of verification and validation (V&V) tests as well as methods for an uncertainty analysis. The main aim of this paper is to investigate these tests and methods applied to CA models by showing results of sample tests and discussing CA specific issues.

Pedestrian behavior during evacuation from road tunnel in smoke condition—Empirical results

Five evacuation experiments were performed in a road tunnel in order to test how pedestrians react when exposed to reduced visibility, how the decision making process is carried out, and finally what is the impact of various circumstances like: different level of smokiness, competitive behavior or learning effect on an evacuation process. In four experiments pedestrians were exposed to artificial, non-toxic smoke. During evacuation of a group of people gathered in low and moderate level of smokiness (when Cs < 0.5m−1) we observed multi-line patterns created by pedestrians. Decision making was engaged in only by the first group of passengers, while under heavy smokiness Cs > 0.7m−1 we have observed decision making by small groups and characteristic double-lines patterns. In four experiments the same group of participants was involved, and a learning effect was observed: increasingly shorter pre-movement time and decreasing time required to leave the main tunnel. We show, that movement speed in smoke is influenced by the evacuees’ attitude and familiarity with environment and evacuation procedures and not only by the visibility level.

Advanced CA Crowd Models of Multiple Consecutive Bottlenecks

Simulation results from two advanced CA based crowd dynamics models, namely Social Distances Model and Bonds Floor Field Model, are investigated using experimental data. Two experiments regarding pedestrian egress from simple network of rooms with multiple consecutive bottlenecks were conducted in Prague and Krakow. Simulation results comparison is the basis for discussion about models properties.

Granularity of Pre-movement Time Distribution in Crowd Evacuation Simulations

This paper addresses issues of spatial distribution of pre-movement time. Three different, real life cases of egress are analysed. In all the analysed cases a coarse spatial distribution of pre-movement time is observed. On the basis of the examples the authors investigate whether this phenomenon has a significant influence on the evacuation process. It has been found that in more complex scenarios, the spatial distribution of pre-movement time affects the evacuation process, while in simple scenarios (like large room evacuation) no significant influence is observed. Finally, some factors that increase the magnitude of the observed phenomenon were identified, namely the complicated geometry of the facility, evacuees confusion, existence of groups and appearance of a leader. As a consequence of the findings, it is recommended to include coarse spatial distribution of pre-movement times in simulations of complex scenarios.

An Expanded Concept of the “Borrowed Time” in Pedestrian Dynamics Simulations

Discretization in numerical simulations holds big advantage of decreasing complexity of calculations, allowing for faster and larger-scale simulations. However, such a procedure leads to emergence of unwanted phenomena due to finite space and/or time resolution. For this reason when space is discretized usually regular lattices are used as they preserve highest rotational and translational symmetry. Highest natural isotropy is obtained by using hexagonal grid. However, for pedestrian dynamics applications due to natural tendency of humans to build square-based buildings and typical big size of the cell square grid allows drastically better space representation. This paper describes how a borrowed time concept can be used to reduce anisotropy in pedestrian dynamics simulations using regular square grid without increasing complexity of the calculation. A simple case of pedestrian movement using expanded borrowed time concept is described and compared with basic approach. A method for generating static potential field with higher isotropy is shown as well.