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.

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.

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

• In the Crowd Source node in the geometry network, make sure you've entered the names of the bones for each body part, so the solver can move the character feet.

• On the Crowd Solver node in the simulation network, on the Particle Behavior ▸ Terrain tab, turn on Agent projection and Agent feet adaptation.

• See foot planting workflow for how to enable better terrain adaptation and prevent skating.