08 Fakultät Mathematik und Physik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/9
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Item Open Access List of parameters influencing the pedestrian movement and pedestrian database(2015) Dridi, Mohamed H.In this paper we present a list of factors influencing the pedestrian behaviour in different situations and conditions. In crowd simulation input we must consider at least two simulation conditions. The first is the normal condition and the second is the emergency condition or panic situation. In panic situations most parameters will be changed and the time factor becomes very important. Both emotion and personality clearly have a strong and considerable impact on individual behaviours in such situations. However, most existing approaches in their attempt to model the behaviour of individuals and for guiding an agent to interact with its environment and other agents, consider the individual as an autonomous agent or autonomous particle that obeys some human-like behaviour modules such as locomotion, perception, and decision making. Other models treat the crowd as a collection of homogeneous particles interacting through physical forces. Today with the enormous knowledge development in computer science, many models try to improve themselves. There seems to be an evolution in crowd simulation to model each individual as some kind of intelligent agent with attempts to incorporate more and more social and psychological factors into the agent behaviour model. However, to reproduce more realistic simulation behaviours many factors and attributes influencing pedestrians must be considered. The actual shortcoming of the existing models is the absence of modelling the social group process and its impact on human behaviour. One way to gain a better understanding of human behaviour in this area is to enrich the tools available for planning, such as pedestrian micro simulation in case of panic situations and emergency conditions. In this work a pedestrian database called PedGUI containing a lot of information about pedestrians is developed, this have a significant impact on the simulation input at least two mean pedestrian characteristics like age and gender can be considered.Item Open Access Pedestrian flow simulation validation and verification techniques(2015) Dridi, Mohamed H.For the verification and validation of microscopic simulation models of pedestrian flow, we have performed experiments for different kind of facilities and sites where most conflicts and congestion happens e.g. corridors, narrow passages, and crosswalks. The validity of the model should compare the experimental conditions and simulation results with video recording carried out in the same condition like in real life e.g. pedestrian flux and density distributions. The strategy in this technique is to achieve a certain amount of accuracy required in the simulation model. This method is good at detecting the critical points in the pedestrians walking areas. For the calibration of suitable models we use the results obtained from analysing the video recordings in Hajj 2009 and these results can be used to check the design sections of pedestrian facilities and exits. As practical examples, we present the simulation of pilgrim streams on the Jamarat bridge (see Figure 5). The objectives of this study are twofold: first, to show through verification and validation that simulation tools can be used to reproduce realistic scenarios, and second, gather data for accurate predictions for designers and decision makers.Item Open Access Simulation of large scale pedestrian flow(2015) Dridi, Mohamed H.; Wunner, Günter (Prof. Dr.)Pedestrian simulation is a challenging and fruitful application area for particle simulation, especially in places where many people are gathered (e.g. the Hajj, sports and concert events). Traffic and transportation domains take advantage of this simulation as well. Here the design and implementation involves interesting issues and particle-based modelling allows for the reproduction of pedestrian behaviour to a level of detail beyond pure collision-free locomotion. In this dissertation we will present a prototypical study: a simulation of pedestrian movement throughout the entire Haram area in the city of Mecca, Saudi Arabia, during the busiest Hajj hours. The objectives of this study are twofold: firstly to gather data for accurate predictions for designers and decision makers, and secondly to show, verify and validate that through the use of simulation tools it is possible to reproduce realistic scenarios. Typical questions in pedestrian motion planning and design are: How many minutes would be needed to evacuate a football stadium or a pop concert arena? Where is the best place for pedestrian information or a poster wall to be placed? How many exit signs should be distributed over the area and where should they be placed? How many minutes does a pedestrian need to go from point A to point B in the overcrowded places? Are transfer times still realistic when the pedestrians are not familiar with the layout? For better planning in this area a better understanding of human behaviour is required and one way to achieve this is to improve the tools available for pedestrian planning (such as pedestrian micro simulation). In particular, particle-based simulation has become an attractive paradigm for modelling and simulating pedestrian decision-making and behaviour because it supports a one-to-one correspondence between the subject of observation and the simulated particle. Since pedestrian movement is very complex, a computing method has to be developed to simulate the crowded movement of pedestrians on a virtual area. The method is based on the data and relations published by Predtechenski and Milinski [1], resulting from several thousand observations. In this investigation we have developed two-dimensional space crowd dynamic models to allow for a simulation of high density crowds. This was done by modifying and enhancing various features on existing microscopic models, respecting the properties of the individuals like social force and Cellular Automata models. We have also studied all existing models and their positive and negative properties to describe a real crowd behaviour. Our target was to describe a comprehensive approach to model a large scale of pedestrian scenarios (like pilgrim mobility in Hajj) through integrating a number of models from different research domains. In this dissertation a model based on discrete theory is developed and classical mechanics such as Newton’s laws of motion are used. The sum of all the forces exerted by the particle or acting on this particle is called f. This force requires intensive modelling efforts that will be considered and implemented as force-vectors. In this work we will discuss the main forces that can be identified as acting on a pedestrian. This model was developed from image data (so called empirical data) taken from a video camera or data obtained using human observers. We consider the individuals as self-driven particles interacting through social and physical forces, which is one approach that has been used to describe crowd dynamics. The behaviour of the pedestrians can be observed from video tapes and from the given task cycle. Since not all behaviour of pedestrians has a major global effect on the overall capacity, the main affecting behaviour has to be extracted and used as input for the computer model.Item Open Access Simulation of high density pedestrian flow : a microscopic model(2015) Dridi, Mohamed H.In recent years, modelling crowd and evacuation dynamics has become very important, with increasing huge numbers of people gathering around the world for many reasons and events. The fact that our global population grows dramatically every year and the current public transport systems are able to transport large amounts of people heightens the risk of crowd panic or crush. Pedestrian models are based on macroscopic or microscopic behaviour. In this paper, we are interested in developing models that can be used for evacuation control strategies. This model will be based on microscopic pedestrian simulation models, and its evolution and design requires a lot of information and data. The people stream will be simulated, based on mathematical models derived from empirical data about pedestrian flows. This model is developed from image data bases, so called empirical data, taken from a video camera or data obtained using human detectors. We consider the individuals as autonomous particles interacting through social and physical forces, which is an approach that has been used to simulate crowd behaviour. The target of this work is to describe a comprehensive approach to model a huge number of pedestrians and to simulate high density crowd behaviour in overcrowding places, e.g. sport, concert and pilgrimage places, and to assist engineering in the resolution of complicated problems through integrating a number of models from different research domains.Item Open Access Tracking individual targets in high density crowd scenes analysis of a video recording in Hajj 2009(2015) Dridi, Mohamed H.In this paper we present a number of methods (manual, semi-automatic and automatic) for tracking individual targets in high density crowd scenes where thousand of people are gathered. The necessary data about the motion of individuals and a lot of other physical information can be extracted from consecutive image sequences in different ways, including optical flow and block motion estimation. One of the famous methods for tracking moving objects is the block matching method. This way to estimate subject motion requires the specification of a comparison window which determines the scale of the estimate. In this work we present a real-time method for pedestrian recognition and tracking in sequences of high resolution images obtained by a stationary (high definition) camera located in different places on the Haram mosque in Mecca. The objective is to estimate pedestrian velocities as a function of the local density.The resulting data of tracking moving pedestrians based on video sequences are presented in the following section. Through the evaluated system the spatio-temporal coordinates of each pedestrian during the Tawaf ritual are established. The pilgrim velocities as function of the local densities in the Mataf area (Haram Mosque Mecca) are illustrated and very precisely documented. Tracking in such places where pedestrian density reaches 7 to 8 Persons/m2 is extremely challenging due to the small number of pixels on the target, appearance ambiguity resulting from the dense packing, and severe inter-object occlusions. The tracking method which is outlined in this paper overcomes these challenges by using a virtual camera which is matched in position, rotation and focal length to the original camera in such a way that the features of the 3D-model match the feature position of the filmed mosque. In this model an individual feature has to be identified by eye, where contrast is a criterion. We do know that the pilgrims walk on a plane, and after matching the camera we also have the height of the plane in 3D-space from our 3D-model. A point object is placed at the position of a selected pedestrian. During the animation we set multiple animation-keys (approximately every 25 to 50 frames which equals 1 to 2 seconds) for the position, such that the position of the point and the pedestrian overlay nearly at every time. By combining all these variables with the available appearance information, we are able to track individual targets in high density crowds.