CROWD SIMULATION

Crowd simulation is the process of simulating the movement of a large number of objects or characters, now often appearing in 3D computer graphics for film.
The need for crowd simulation arises when a scene calls for more characters than can be practically animated using conventional systems, such as skeletons/bones.
Animators typically create a library of motions, either for the entire character or for individual body parts. To simplify processing, these animations are sometimes baked as morphs. Alternatively, the motions can be generated procedurally - i.e. choreographed automatically by software.
The actual movement and interactions of the crowd is typically done in one of two ways:
Particle Motion: The characters are attached to point particles, which are then animated by simulating wind, gravity, attractions, and collisions. The particle method is usually inexpensive to implement, and can be done in most 3D software packages. However, the method is not very realistic because it is difficult to direct individual entities when necessary, and because motion is generally limited to a flat surface. Crowd AI: The entities - also called agents - are given artificial intelligence, which guides the entities based on one or more functions, such as sight, hearing, basic emotion, energy level, aggressiveness level, etc.. The entities are given goals and then interact with each other as members of a real crowd would.