Terrain

A Terrain (class 218) component in a scene points at a TerrainData (class 156) in a shared asset file and adds the drawing settings. The data holds the heightmap, the splat layers with their blend maps, and the trees. Of the games here only Sledding Game uses terrain; SkateBIRD’s scenes have none. Observed · Sledding

Heightmap

m_Heightmap holds m_Resolution × m_Resolution samples, row z then column x, as 16-bit integers. A sample is 0 to 32,766 for 0 to 1 of the terrain’s height, so TerrainData.GetHeight is h / 32766 × size.y metres. Samples are m_Scale.x and m_Scale.z metres apart from the terrain’s position, so the terrain is (resolution − 1) × scale wide. Sourced · Unity scripting reference

The heightmap also stores two precomputed arrays for drawing, m_PrecomputedError (1,365 entries) and m_MinMaxPatchHeights (2,730), over m_Levels = 5 levels. Proven · Sledding Holes are one byte per cell, (resolution − 1)² of them, 0 meaning a hole; a terrain without holes stores none. Observed · Sledding

Splat layers

m_SplatDatabase stores the terrain layers (m_TerrainLayers, references to TerrainLayer objects), the blend maps (m_AlphaTextures, textures of RGBA weights, four layers per texel, texel row 0 at z = 0 as Unity stores rows), the blend map resolution (m_AlphamapResolution) and a base map resolution. Observed · Sledding

A TerrainLayer (diffuse, normal and mask textures) stores the tile size and offset, a specular colour, metallic, smoothness, a normal scale, and a min/max remap of the diffuse and the mask channels. Observed · Sledding

Trees

The tree prototypes and instances are in the data’s detail database (m_DetailDatabase): m_TreePrototypes (each a prefab) and m_TreeInstances. An instance has a position as 0 to 1 of the terrain’s size, a width and a height scale, a rotation about y in radians, a colour (32 bits), and its prototype index. Its world matrix is T(terrain position + position × size) · Ry(rotation) · S(width, height, width). Observed · Sledding

Sledding Game’s terrains

In build 26054124 the mountain scene (level1) draws 25 terrains and has 21,147 terrain tree renderers. Observed · Sledding The rest of this section was measured on build 25351629, where the mountain scene (level1) has nine Terrain components, each with a TerrainData in sharedassets1.assets. Proven · Sledding

Property	Value, for all nine	Confidence
heightmap	513 × 513 samples (263,169), scale 1.953125 m × 600 m × 1.953125 m, so 1,000 m wide	Proven · Sledding
holes	none	Proven · Sledding
splat layers	3, one blend map of 512 × 512	Proven · Sledding
tree prototypes	3	Proven · Sledding
detail prototypes (grass)	none	Proven · Sledding

The nine terrains hold 1,191, 1,742, 991, 764, 1,132, 1,787, 2,575, 1,437 and 702 trees: 12,321 in all. Proven · Sledding Together they tile a 3 km × 3 km mountain, by their 1,000 m sides and the grid of the scene. Inferred

Every Terrain component states the same drawing settings: draw heightmap, instancing off, trees and foliage drawn to 1,500 m, a heightmap pixel error of 20 and a splat map distance of 1,000 m. Proven · Sledding

The terrain collides through the heightfield; a TerrainCollider can point at its own TerrainData, whose heights can differ from the drawn ones. Colliders describes the rule. Observed · Sledding

The terrain shader

The terrain material’s shader and how the three layers blend with the base map in Sledding Game’s URP terrain shader are not described here. No frame capture of a Unity game holds a terrain draw: the captures of Hollow Knight (2D), SkateBIRD (no terrain in the player) and ULTRAKILL are of title or main-menu screens, and those of Lethal Company and Risk of Rain 2 of a launch-mode menu and a sign-in dialog, although the players of both hold Terrain components (6 in Lethal Company, 10 in Risk of Rain 2). Observed · the captures read Sledding Game has no capture. What would settle it: a Direct3D 11 frame of Lethal Company or Risk of Rain 2 taken inside a level with a terrain in view (the draw’s shader, its splat-map and layer textures and constants); the captured frames so far reach no level.