Houdini 16.5 Crowd simulations

Specifying terrain for crowds

How to specify terrain geometry for agents to walk across.

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The Crowd solver has can have your agents stick to terrain geometry, and do some foot placement on the terrain. Only one geometry object can be used as terrain with a crowd solver. If agents move off the terrain, they will snap to the ZX plane.

Houdini crowds currently do not support multi-level terrain. For example, you cannot have a terrain object with underpasses or structures with roofs. Agents will always snap to walk on the topmost surface.

Set the terrain for a crowd simulation

  1. Select the geometry you want to use.

  2. On the Crowds shelf tab, select the Terrain tool.

    This selects the Crowd Solver node, turns on the terrain following controls on the Terrain sub-tab, and sets it to the selected geometry.

    You can limit the terrain following behavior to certain groups by putting a space-separated list of group names in the Agent Group field.

    You also adjust or turn off automatic foot placement.

Foot adaptation

The crowd solver can manipulate agent skeletons to automatically place agent feet in proper position as they walk along non-flat surfaces.

See also

Crowd simulations

Getting started

The moving parts

  • Agents

    About agents, the moving "actors" that make up a crowd simulation.

  • States

    About agent states, the virtual "mood" of each agent which controls the agent’s animation and which behaviors it runs.

  • Clips

    How to associate animation with agents in certain states.

  • Triggers

    How to specify conditions that cause agents to change from one state to another.

Next steps

  • Foot planting

    How to set up agents to adapt their animation to terrain and prevent skating.

  • Transition graphs

  • Attributes

    Useful attributes for reading in triggers, or that you can set to affect behavior.

  • Sensors

    How to make agents behave differently based on their virtual senses.

  • Diversity

    How to create a more realistic crowd by making agents look and act differently.

  • Weights

    How the Houdini crowd solver decides which behaviors to apply to an agent at each time step.

  • Terrain

    How to specify terrain geometry for agents to walk across.

  • Obstacles

    How to set up obstacles for agents to avoid.

  • Dynamics interaction

    Tips on setting up interaction between agents and other types of dynamics.

  • Ragdoll simulation

  • Adding direction

    How to assert manual control over different aspects of the crowd simulation.

  • Fuzzy Logic

  • Caches

    Tips for efficiently caching and loading crowd sims.