Map altitude

In the Simple or Expert Inspector, open Map altitude, enable Enable Map Altitude, set Altitude Min Height and Altitude Max Height, then generate again. The feature is off by default and works in Procedural and Image modes. Turning it off and regenerating restores the previous relief.

The minimum and maximum are additive offsets in map units, before the generator transform's scale. Existing mountains, plateaus, seabed depth and the 0.02 path recess remain on top of this field, so they may exceed these bounds. Equal bounds produce a uniform vertical offset; negative heights are supported.

Automatic height map

Leave Altitude Height Map empty. Broad, seeded noise hills are generated and normalized between the minimum and maximum. Altitude Noise Scale controls their frequency in cell units; lower values produce broader hills. Start with 0–8 units and 0.035. Keep Use Random Seed disabled and Seed unchanged for repeatable geometry. Changing altitude does not consume Unity's random stream or change strategic feature placement. Automatic altitude does not impose symmetry on the hills.

Custom height map

Assign a grayscale Texture2D to Altitude Height Map. This is a separate texture from Source Map Image and does not change terrain classification. In the texture importer, enable Read/Write, disable sRGB (Color Texture), choose Compression: None, and Apply. Keep sufficient Max Size to retain the source detail. An unreadable texture stops generation with an actionable validation error.

Black is the minimum, white is the maximum, and intermediate grayscale values interpolate between them. Custom values are not auto-normalized: a uniform gray image gives a uniform intermediate offset. The entire image fits the square terrain footprint regardless of its aspect ratio. Sampling is bilinear, independent of the texture filter/wrap mode. By default the bottom-left pixel maps to minimum local X/Z; Altitude Height Map Origin Top Left flips the vertical axis. Samples outside the map clamp to its edge, including shoreline overlaps and cliff skirts.

Geometry and runtime data

When altitude is enabled, MeshGround/MapSides closes the outer terrain down to a common base. Its rock faces follow the final perimeter, including path recesses, coastal floor extensions and the lower edges of existing mountain walls. Mountain Material is used first, then Env Material or Grass Material. The side mesh has a matching collider and embedded geometry for saved scenes. Disabling altitude and regenerating removes these additional faces.

Controlled terrain example with an automatic height map, a river and a mountain touching the map border:

Before	Closed sides

Each freshly generated terrain and water vertex receives the adjusted vertical offset at its final X/Z position, after contour and path smoothing. Mesh indices, shared vertices, UV seams and shader facet markers are retained. Normals and bounds are rebuilt and colliders are recooked from the displaced mesh. Embedded mesh data captures the final geometry, without applying the offset again when the scene reloads.

Grass is placed by MapPropsGenerator on the final displaced terrain colliders, using the same large-then-small passes and shared prefab meshes. Its placement probes follow the terrain bounds and slightly embed accepted footprints to avoid floating roots. See Grass prefabs.

Other props, resources and cliff prefab instances follow the field at their pivot and keep their original shape and orientation. Very steep custom relief can therefore leave large rigid props partially embedded or overhanging. River bridges connect the raised endpoint heights with their rigid deck. The aerial navigation mesh, when Enable Aerial Generation is enabled, follows the final ground and water with Aerial Clearance world units of clearance (3 by default). This output is disabled by default. Mountain peaks and rock feet do not lift the flight surface: it continues through the massif at the underlying regional altitude. The rock's own collider remains a physical obstacle where it protrudes above the plane. The mesh and its collider retain this intersection when embedded geometry reloads. A separate game navigation bake must include protruding rock as obstacles. The altitude phase does not deform source prefab or texture assets.

result.Grid.AltitudeHeightMap is a generation snapshot. Its Sample(terrainX, terrainZ) method accepts X/Z in the local space of result.MapRoot.Find("MeshGround/Terrain"), including Cell Size. The field can be sampled without retaining a readable texture after generation. This snapshot includes the water constraints below. MapAltitudeHeightMap.Create returns the raw recipe field; use the result grid's snapshot to match the generated geometry around water. GridCell.Height and MountainHeight include the cell-center altitude; GridCell.AltitudeOffset records that offset. ClampCellHeight preserves the global altitude while clamping the underlying local feature height. Player spawn positions and saved generation recipes include the new relief.

Water levels and banks

Water constraints apply automatically when both altitude and water are enabled, with automatic or custom height maps. Lakes, seas and closed pools use one horizontal level per connected water surface. Disconnected basins can have different levels. Their level uses the mean height-map offset over that basin.

In the River layout, channels reaching separate map-boundary mouths use the lowest mean mouth as their outlet. The surface follows a common distance-to-outlet profile, so branches join continuously and water can descend toward that outlet. The grade is capped at 8 percent. Closed pools without through-flow stay level. This removes the height map's repeated uphill/downhill waves from the water.

The seabed receives the same correction, retaining its local depth/noise. Banks follow the water over the visible shoreline and three further cells, then blend back into the height map over four cells. This keeps the water attached to its banks. Bridge decks use the adjusted landing heights; water collision and optional minimap meshes retain their final levels when embedded geometry reloads. The source height-map texture is unchanged. Relief far from water keeps its original field.

Controlled custom height-map examples, identical recipes and cameras:

Water	Before	Corrected altitude
Lake
River

Strong custom height-map differences can still produce steep banks within the transition band.

This stage retains the strategic flags and layout score. It does not yet recompute walkability/buildability from slope, level base footprints, simulate time-dependent fluid flow or create waterfalls, terrain holes or elevated land bridges. Bake or update your game's navigation from the generated colliders as appropriate.