Research On The Construction Of Crowd Evacuation Simulation Environment Based On Scene Semantics

In recent years, with all kinds of fire accidents and emergency events happened frequently,the simulation of safety evacuation has been taken more and more attention when an emergency or disaster occurs in the public. For larger labor-intensive and liquidity places such as schools,chemical plants, tourist attraction or squares, once an accident occurs, if not timely evacuating, it will cause a great losses of lives and property. Therefore, establishing an effective simulation scenario model simulated by computer, it is of great significance to help solve the crowd movement in public environment, and also reduce the risk of accidents. With the development of computer technology, computer simulation used to implement the construction of virtual scene is gradually becoming a hotspot in the field of computer graphics and virtual reality research. The crowd evacuation simulation is a hot problem in virtual experiment. It is an important branch in the field of simulation. The simulation of crowd evacuation has a great significance. It contributes to the formulation of corresponding contingency plans, guides the design of the scene,as well as can prevent or reduce the casualties in emergency situation.In order to simulate the crowd movement, we need to build the scene modeling applied to crowd simulation especially for large complex scenes. The research of virtual environment in crowd simulation mainly divided into two aspects of building and rendering. The building process is mainly based on the real environment for crowd simulation, it is to create a geometric model, and to display 3D virtual environment by using the certain scene management technology.Traditionally construction of simulation environment depends on 3D scene modeling. However this method is inefficient and takes a long period due to the complexity of modeling. Under the condition of lack of 3D models, if we directly use 2D map image to build the scene, it can also provide the identification model of the semantic environment successfully when public security crisis occurs, and it has a high efficiency to extract information process relatively.This article propose the method of building the scene based on the 3D model and extracting semantic information based on OSG; the method of building the scene based on the 2D map and extracting semantic information based on GIS. And we put forward a kind of method about route planning based on semantic information. Finally construct the crowd simulation system tosupport the crowd evacuation.(1) We put forward the method of extracting semantic information based on OSG. In the Maya we build a 3D model, import into the OSG platform, and extract the semantic information in the scene. Then analysis the semantic information, and save the results in the format of the XML text, the text can provide the necessary information for the path planning and crowd simulation.(2) In order to reduce the complexity of scene modeling, this paper puts forward an efficient method for enhancing a road map from GIS data to construct a road scene to be used in crowd simulation. In this paper, we extract geometrical information(e.g., vector data) of the roads from the 2D map by using geographic information system(GIS). Then we define the topological relationship and generate the topological graph of the roads. Based on the above geometrical and topological information, we transform GIS data into road scenes for crowd simulation given a2 D map. The simulation results show that the method can significantly improve the efficiency of environment construction and crowd simulation in the complex scene.(3) In the simulation of crowd evacuation, how to guide the virtual crowd through the complex environment and to avoid collision with the obstacles to reach the desired goal that is a problem, we put forward a kind of route planning method based on semantic information. This method using semantic information can realize global path planning firstly, and then using the potential field method to avoid collision with obstacles, finally the rapid evacuation of the crowd is finishing. The simulation results show that the method can produce high quality path and guide the virtual crowd movement quickly and flexibly in complex scenes to improve the efficiency of the evacuation.(4) Based on the above methods and the research projects of the laboratory, we design the crowd evacuation simulation system architecture. And based on the VS 2012 + OSG platform,we develop the modeling and simulation of crowd evacuation system. Simulation results show that the system has realized the environment modeling and crowd evacuation simulation movement. It has authenticity and is very practical.