2 Overview of Crowd Simulation in Computer Graphics

INTRODUCTION igh-powered technology use computer graphics in education, entertainment, games, simulation, and virtual heritage applications has led it to become an important area of research. In simulation, according to Tecchia et al. (2002), it is important to create an interactive, complex, and realistic virtual world so that the user can have an immersive experience during navigation through the world. As the size and complexity of the environments in the virtual world increased, it becomes more necessary to populate them with peoples, and this is the reason why rendering the crowd in real-time is very crucial. Generally, crowd simulation consists of three important areas. They are realism of behavioural (Thompson and Marchant 1995), high-quality visualization (Dobbyn et al. 2005) and convergence of both areas. Realism of behavioural is mainly used for simple 2D visualizations because most of the attentions are concentrated on simulating the behaviours of the group. High-quality visualization is regularly used for movie productions and computer games. It gives intention on producing more convincing visual rather than realism of behaviours. The convergences of both areas are mainly used for application like training systems. In order to make the training system more effective, the element of valid replication of the behaviours and high-quality visualization is added. Real-time crowd simulation is a process of simulating the movement of a large numbers of animated characters or agents in the real-time virtual environment. Crowd movement in certain cases requires the agents to coordinate among themselves, follow after one another, walking in line or dispersing using different directions. All of these actions will contribute to the final collective behaviours of the crowd that must be achieved in real-time. Unlike non-real-time simulations which are able to know the full run of the simulated scenario, real-time simulations have to react to the situation as it unfolds in the moment. As stated by Thalmann and Musse (2007), real-time rendering of a large number of 3D characters is also a challenge, because it can exhaust the system resources quickly even for a powerful system. Figure 2.1 Previous works in crowd simulation Figure 2.1 shows a timeline of the previous works that have been done in crowd simulation fields. A behavioral animation of human crowd was based on foundations of group simulations of much more simple entities, notably flocks of birds (Reynolds 1987) and schools of fish (Tu and Terzopoulos 1994). Earliest procedural animation of flocks of virtual birds …