Far-field ground colour

Every 512 m cell ships a pre-baked albedo of the whole cell (fields, roads, snow, sand), used beyond the near-field clipmap (Near-field ground). It is split over two swatches in textures\tbheightfield\swatches\, whose names are the engine’s even though they look swapped: the “colour” texture holds the normal and a luminance, the “normal” texture holds chroma. :observed The formula is read from the terr_mega G-buffer pixel shader. Observed

uv  = (X, Z) · BlendMapScale.xy + BlendMapOffset.xy        absolute world X/Z
      BlendMapScale = (1/512.5, −1/512.5)                   (material params, type 0: guid16 + float4)
      → u = (X − X0 + 0.25) / 512.5,   v = (Z0 + 512.25 − Z) / 512.5     X0, Z0 = cell minimum; row 0 = north
A   = TerrainColourTexture(uv)  = mainmap_x<lx>_z<lz>_x<season>x_diff   (BC7, linear)   rg = normal xy, a = luminance
B   = TerrainNormalTexture(uv)  = submap_x<lx>_z<lz>_x<season>x_diff    (BC7 sRGB)      rgb = chroma
far_albedo = B.rgb · A.a²      (linear)
albedo     = lerp(near_clipmap, far_albedo, saturate(ring − 6))

The material slot hash is 0x9C1C3F4E (TerrainColourTexture; 0x98F344DA on roads). The half-texel border makes neighbouring cells share their edge texels. Observed Quality tiers are the same image at different sizes: q1 to q3 (128 to 512 px) in GeoChunk0, q4 (1,024) and mainmap q5 (2,048 px = 0.25 m per pixel) in GeoChunk2. Observed Which pair a season uses is read from the cell’s terr_mega instances (Seasons), not from _x<season>x_ in the names. Observed uber_megaroad uses the same far-field base plus a near-field tint from its roadblend _tint_ map at TEXCOORD2; city uber_road meshes have their own textures. Observed

In the Shibuya cell the submap stores four tiers (1,024, 512, 256 and 128 px) and the mainmap five (2,048 down to 128), each tier one block-compressed level. Observed · the one pair every terrain material of the box reads The baked colour B.rgb · A.a² at the 1,024 px submap tier (0.5 m per pixel) carries the road markings: zebra crossings, lane lines, kerb lines and painted text are separate marks of one to a few pixels; at the 256 px tier (2 m per pixel) the same marks are smeared into grey bands. Observed[the cell’s pair, both tiers viewed] The stored data has smooth horizontal bands over the whole cell: the row means of the mainmap alpha range 60 to 108 with a dominant period of 27 m (108 rows at 2,048 px, 54 rows at 1,024), and the submap’s green row means range 235 to 248 with the same 27 m period; the period in metres is the same at every tier. Observed · the cell’s pair, three independent BC7 decoders The three decoders give identical RGBA on all four tiers read (0 differing texels in 4,194,304, 1,048,576, 1,048,576 and 262,144), so the bands are in the stored swatches, not a decode artefact. Observed · three decoders over four tiers of one pair

The far-field roughness is sat(TerrainGlossTexture(uvB).r / 0.93) and the normal is x = 2A.r − 1, z = 2A.g − 1, y = sqrt(sat(1 − x² − z²)) in world space, from the mainmap A (Other world families). Observed

Water seen through it

The water’s colour is the far-field terrain colour below it seen through the water (Water). Observed

Where the near field takes over

The pixel shader tests rings k = 0..6; outside every ring the ring index is 255, and albedo = lerp(near, far_albedo, saturate(ring − 6)) blends the outermost ring into the far field. Observed Ring 6 is 0.25 m per texel, exactly the far-field texel, if the first layer record of 1,024 texels covers 4 m. Inferred