Terrain

Terrain is uneven ground made of detail brushes you sculpt with the mouse. What it is and its limits are in Terrain.

Make terrain

1. Draw a box where the ground should be, inside a room. Its top is where the ground starts.
2. Select it.
3. Press H for the terrain tool and set Cell size in its panel: how far apart the ground's points are.
4. Click Convert Selection to Terrain.

Or right-click the brush and choose Convert to Terrain; it uses the cell size last set in the panel.

The box is replaced by a grid of prisms. It converts only if it is solid or detail and has a flat top and upright sides; a room's own air brush is not ground and is refused. When nothing converts, the status bar says why. A side gets at most 64 cells, however small the cell size.

The prisms are detail, whichever volume you drew the box in: ground is dressing standing in a room, so a solid box stops carving when it becomes terrain.

Sculpt

Sculpting works in the 3D view only.

1. Press H.
2. Point at the terrain. A ring shows the brush.
3. Hold the left mouse button to raise the ground under the ring. Hold Shift as you press to lower it instead; the ring turns red.
4. Let go. Each stroke is one undo step.

A stroke stays on the terrain it started on. The ground cannot be dug below the bottom of the original box.