Once you have loaded an actor, and possibly added one or more emitters, you can emit particles and create the crowd simulation. When the particles are emitted, an instance of each actor in the Crowd model is "attached" to each particle.
If you don't want to use specific emitter objects, a default emitter object is created automatically when you create a crowd simulation.
There are two types of basic crowd simulations you can choose to create: Pedestrian or Stadium. See below for an explanation of each. You can also have multiple crowd simulations in a scene.
Creating a Pedestrian (Locomotion) Simulation
A pedestrian crowd simulation is a locomotion-type simulation that allows actors to move along the XZ plane. This lets you create typical crowd simulations of people walking around in the city, running through fields, teams playing sports, and so on. Of course, you can create other interesting effects as the scene requires, such as if you're using animals, zombies, cells, or other non-humans as the actors.
To emit the particles and create a pedestrian simulation:
Load one or more actors as described in Loading Actors for the Crowd Simulation.
Make sure that the action sources you load for the actor are appropriate for locomotion - see Loading Action Sources for an Actor.
If you want to use specific emitters, create them and add them to the Crowd model as described in Crowd Particle Emitters.
Choose the CrowdFX 
Simulation Create Pedestrian command from the ICE toolbar.
If you didn't already select emitters for the simulation, a directional emitter is automatically created at the scene's global origin.
The simulation point cloud is created and added to the Crowd model. This point cloud contains several ICE trees that set up the crowd simulation - see the section below for more information.
The particles are emitted evenly from the surface of the emitters, and you can set the particle emission properties in the Emit Evenly from Geometry property editor that appears. See also Setting Up the Crowd Particle Emission.
Creating a Stadium (Stationary) Simulation
In a stadium crowd simulation, the actors stay in one location (they're stationary). This lets you create typical crowd simulations of people cheering on their favorite sports teams, sitting in an audience, standing around idly and chatting, and so on.
To emit the particles and create a stadium simulation:
Load one or more actors as described in Loading Actors for the Crowd Simulation.
Load an action source as described in Loading Action Sources for an Actor.
Stadium simulations use one action source by default. You should select an action source in which the animation does not move in global space, and is considered "stationary."
If you want to use specific emitters, create them and add them to the Crowd model as described in Crowd Particle Emitters.
Choose the CrowdFX Simulation Create Stadium command from the ICE toolbar.
If you didn't already select emitters for the simulation, horizontal polygon mesh bleachers are automatically created as the emitters. You can adjust the size, placement, and number of bleachers in the Bleachers compound that's created in the emitter's ICE tree.
The simulation point cloud is created and added to the Crowd model. This point cloud contains several ICE trees that set up the crowd simulation - see below for more information.
The particles are emitted evenly from the surface of the emitters (one particle per polygon), with an instance of an actor in the Crowd model "attached" to each particle. Set the particle emission properties in the Emit From Horizontal Polygons property editor that appears. See also Setting Up the Crowd Particle Emission.
The Crowd Simulation Point Cloud
The Point_Cloud object in the Crowd model is the point cloud that drives the crowd simulation. It has several ICE trees in it, as described here:
The Shape Instance Skinning ICE tree stores data that is used by the realtime skinning shader when you view the Mesh Proxy in an OpenGL display mode, as described in Viewing the Actor's Envelope. Normally, the Actor Copies mesh is displayed as the deformed envelopes of each actor instance in any view.
Adding More Crowd Simulations to the Scene
You can create multiple crowd simulations (multiple Crowd models) in a scene. For example, you could have both pedestrian and stadium simulations in the same scene to create stands full of enthusiastic football fans cheering on their favorite players who are running around on the field.
The actors in each crowd simulation don't interact with each other because they are not in the same Crowd model and have no way of detecting each other (see Collision Avoidance Behavior for Actors). As well, the actors in each crowd simulation respond only to the goals, obstacles (walls), and terrains that are in their own Crowd model.
However, you can use the same original source model to create actors in any crowd simulation. Likewise, you can use the same goal, wall, and terrain objects in multiple crowd simulations as long as you identify them properly for each Crowd model.
To add another crowd simulation:
Choose the CrowdFX Crowd Create New Crowd command from the ICE toolbar.
This creates a new Crowd model with the next available number appended to its name (such as Crowd1, Crowd2, etc.), and containing all the typical nodes and groups - see Anatomy of a Crowd Simulation.
Load one or more actors as described in Loading Actors for the Crowd Simulation.
Setting and Selecting the Current Crowd
When you have more than one crowd simulation (Crowd model) in a scene, you need to set which one is the current crowd. When you create a new crowd, it is automatically set as the current crowd.
Being the current crowd means that when you choose CrowdFX commands from the ICE toolbar, the current crowd is the only one to which these are applied. All crowds will simulate normally whether or not they are current.
Select any Crowd model in the explorer and do either of the following:
Crowd Edit Set As Current Crowd command from the ICE toolbar.
