Coordinates, cells and the map

Frame and units

The world is Y-up and left-handed, one unit = one metre. A mesh header’s quantisation, for example scale = (256, 32, 256), translate = (−1792, 96.021, −9984), reproduces its observed world box exactly. Observed Direct3D conventions apply: row vectors, p' = p · M, v pointing down the image. Observed

The Brio track spans x −12,548..9,487 and z −11,281..10,754 on the pause map (22,035 m square, see below); the Tokyo city lies in its southern half (the Shibuya area is around x −2,050..−850, z −5,390..−4,190 and the Tokyo core around x −816..−560, z −5,156..−4,900). Observed

Grids

Grid	Size	Rule	Confidence
Terrain cells	512 m	a cell covers [512 i, 512 (i+1)) in X and Z; a tile named ..._x<label>_z<label>_... uses label = cell index × 1023 (autoterrain_x-1023_z-10230 is cell (−1, −10))	Observed
proc placement cells	50, 75, 100, 125, 150, 200, 250, 300, 500, 10,000 m	origin (cx × cs, 0, cz × cs)	Observed
Far-field ground texel	0.25 m	mainmap 2,048 texels per 512 m cell	Observed

A placement file’s cell does not bound its instances: 337,778 of the 29,164,671 .pgeo instance records lie outside the cell the file is kept under, while none lies outside the file’s header box (widened by one fixed-point step and an f32 rounding). Proven The 297 files whose header box meets the box x −1550..−1100, z −5000..−4566.67 hold 68,556 instances and 30 crowd splines in it, and the same are found by reading every file. Observed

Objects that stand over a cell edge

An object may reach into an area while its origin is outside it. Its reach is bounded by the model’s oriented box from the hand-placed instance bounds, not by the template library’s box. The largest reach of any placement of each category over all four seasons is: Observed

Category	Max reach (m)	By
props	92.9	prp_fst_balloon_hotair_c
rocks	68.3	roc_alp_module_embedded_a_small_coll
buildings	60.4	gpy_el_mod_ramp_02_c
infrastructure	51.8	inf_fst_tunnel_led_b
bridges	50.7	inf_cst_brdge_03_side_end_a
trees	47.7	tre_gbl_cherry_spg_a (spring)
barriers	27.8	bar_pln_retain_dmnd_01_a
bushes	21.2	bsh_gbl_elm_d
signs	12.4	sgn_cty_pfb_dir_gantry_01_a
grasstemplate	3.7	gcr_lmt_grass_tufty_b
smashables	< 0.1	flattenable-bush proxies

The template library’s AABB is not usable for this: it dropped 5 placements in the Tokyo core and inflated the infrastructure reach to 846 m (Template libraries). Observed The ocean_vista mesh spans x −63,677..99,817, z −100,965..94,764 around the whole map, and its saturated bounds record would put it in every area: its 71 overlapping terrain clusters are all at the map’s edge. Observed

Track locators

media\Tracks\Brio\trackroutes\*.nt are plain XML <TrackLocators> with a <SceneTransform> per locator whose translation is value._41/_42/_43 in world metres. map_region_city.nt gives the Tokyo anchors, for example Arena_000 at (1046.7, 0.23, −6902.6). The numbers agree with placements and terrain. Observed Region outlines (City, Canyon, …) are map_region_*.nt, whose translations (value._41, value._43) are the polygon vertices. Observed

The pause-menu map

The in-game map is a ready-made tile pyramid unrelated to the terrain data: media\UI\Textures\Data_Bound\Map_<Track>_<Season>.zip (for example Map_Brio_Spring.zip). Entries are <level>-<row>-<col>.swatchbin; level 0 is one tile for the whole map, level L is 2^L × 2^L tiles, row 0 is north; Brio ships levels 0 to 3 (85 tiles) of 1,024 px each. Observed

The world extent is set by the game’s own map profile, UI.zip → MapProfiles\MapIncludes\MapIncludeSharedResources.xml: background_size is 22035 m (square) and background_offset is (−12548, 0, −11281), the minimum X/Z corner. So pixel (u, v) of a stitched level maps to x = −12548 + u / W × 22035, z = 10754 − v / H × 22035. Observed

The mainmap_* and submap_* swatches in the GeoChunks are not the pause map: they are the terrain shader’s far-field colour inputs (Far-field colour). Observed