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tokyo-wangan-racing/docs/daikoku-reference-spec.md
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Hermes 4a702a4fdb docs(daikoku): measured reference spec for PA entrance geometry 
Real-world numbers gathered from OSM (Overpass), Esri aerial imagery, and
frame-sampled onboard video. Replaces estimation with measurement.

Key findings:
  * Loop radii MEASURED via Kasa circle fit on OSM ways: 27.5-204 m,
    mean 131 m (469 studs). Two cleanest fits (rms<1.5) are the true
    helixes at 147 m (525 studs) and 124 m (441 studs).
  * 6 of 8 curved ramps turn CLOCKWISE - matches the video captions
    'right, right and you will reach the PA'.
  * FIVE deck layers in the interchange (OSM layer 1-5). Current
    PA_LIFT=56 models only one; faithful build wants 3+ overhead.
  * Real PA footprint 181x174 m (parking) / 203x227 m (rest_area).
    Current APRON 210x200 m already matches well - the divergence is
    SHAPE (square vs rounded wedge), not extent.
  * Scale clarified: PA work uses M=3.571 studs/m, NOT the 4.3 in
    c1_georeference.json (different mapping, 366 m median error).

Video reference archived to NAS 004-video-reference/ (364 MB, 4 routes).
2026-08-03 02:44:46 -04:00

6.2 KiB
Raw Blame History

Daikoku Futo PA — Measured Reference Spec

Source-of-truth numbers for building the Daikoku PA entrance/exit ramps and apron in MapBuilder.luau. Everything here is measured, not estimated: OSM geometry via Overpass (/tmp/osm_daikoku.py), Esri aerial imagery, and frame-sampled onboard video.

Generated 2026-08-03.

1. Scale

Quantity Value
Project scale M = 1/0.28 = 3.571 studs per metre (MapBuilder.luau:69)
Reciprocal 1 stud = 0.28 m
Circuit.STUDS_TO_KM 0.28 / 1000

NOTE: c1_georeference.json records scale_studs_per_meter: 4.3 for the C1 loop georeference. That is a different mapping (real-Tokyo lat/lon → C1 world) with a stated median_error_m: 366. Do not use 4.3 for PA geometry. PA work uses 3.571.

2. The real PA footprint (OSM)

Overpass, bbox 35.4545/139.6700 → 35.4705/139.6935. ENU metres about 35.46246657, 139.68149001 (user's Google Earth point).

OSM way Type Extent (m) Perimeter Name
405966005 highway=rest_area 203 × 227 646 m 大黒PA
59608205 amenity=parking 181 × 174 507 m 大黒ふ頭パーキングエリア
88702527 amenity=parking 102 × 107 359 m (satellite lot, W of main)

Current build: apron is APRON_X = 210*M, APRON_Z = 200*M (MapBuilder.luau:991) = 210 × 200 m. That sits between the parking polygon (181×174) and the rest_area polygon (203×227) — already a good match. The apron extent is not the problem.

The shape is the divergence: the build is an axis-aligned square; the real lot is a rounded wedge bounded on the N/E by the loop ramp arc.

3. Loop ramp radii — MEASURED

Kasa circle fit over each OSM ramp way with |cumulative turn| ≥ 120°. rms = fit residual (low = genuinely circular).

OSM way Length Turn Radius rms Layer Direction
32355896 475 m −272° 70.9 m 14.4 — CW / right
32403901 601 m −217° 147.4 m 1.2 5 CW / right
32592491 729 m +208° 197.4 m 12.7 2 CCW / left
307397558 167 m −178° 27.5 m 9.0 — CW / right
779045459 371 m +161° 123.6 m 0.7 3 CCW / left
32403902 656 m −150° 204.2 m 13.3 3 CW / right
32592481 359 m −146° 120.4 m 12.0 1 CW / right
32592487 488 m −122° 158.8 m 11.3 2 CW / right

Headline numbers

  • Radius range 27.5 – 204 m; mean 131 m = 469 studs
  • The two cleanest circular fits (rms < 1.5) are the true helixes:
    • 32403901 — 147 m (526 studs), 217° of turn, layer 5
    • 779045459 — 124 m (441 studs), 161° of turn, layer 3
  • 6 of 8 curve clockwise (right). Matches the video captions exactly: 右、右と覚えておくとPAに着きます — "remember right, right".

Recommended build values

Ramp Radius (m) Radius (studs) Turn
Main entry helix 147 525 ~220° CW
Secondary helix 124 440 ~160° CCW
Tight connector 71 255 ~270° CW

Current Circuit.PA_RADIUS = 260 studs = 72.8 m — which is almost exactly the tight connector (32355896, 70.9 m). The main helixes are roughly 2× that.

4. Deck layers — the vertical stack

OSM layer tags on bridge ways in the interchange:

Layer Bridge ways Total length
1 11 17,696 m
2 7 5,637 m
3 8 5,368 m
4 10 10,096 m
5 6 1,417 m

Five distinct deck levels. This is the single most important structural fact: Daikoku JCT is a five-level stack, and the PA sits at the bottom of it.

Current Circuit.PA_LIFT = 56 studs (15.7 m) of clearance over the apron — that is one level. A faithful build wants at least 3 visible levels overhead.

Typical Japanese expressway deck-to-deck spacing is ~10–12 m; at 3.571 studs/m that is 36–43 studs per level.

5. Video-derived detail

Sources archived at unraid-1:/mnt/user/data/yy-roblox-games/0-tokyo-wangan-racing/004-video-reference/

Route Video ID Len Light Value
CMT TOKYO "How to go to?" 91suWmNr62c 2m50 night narrated turn-by-turn
Bay Bridge up (ベイブリッジ〜大黒PA) PK4BachUlYo 2m36 night full entry sequence
Yokohane down (横羽線下り) zlmdaR0opgE 5m15 day best structural read
Honmoku JCT (攻略車載#18) fNHucFnFQ1c 10m07 day approach + JCT
Night walkaround 7i0-KCwMDyc 10m40 night apron-level atmosphere

Confirmed visual details

  1. Red/orange chevron shoulder paint on the outer kerb through every ramp curve. Present in all five videos, day and night. Highest-value cheap detail available.
  2. White splayed / V-shaped piers with trapezoidal box-girder deck underside (clearest at yokohane_down t=218–242s).
  3. Chain-link mesh fencing along ramp edges — not solid barrier. Above a low concrete jersey base.
  4. Green route shields 大黒線 K5; blue circular regulatory signs; 50 km/h limit discs on ramps.
  5. /P + up-right arrow gantry marks the parking entry (91suWmNr62c t=104s).
  6. Apron at night: warm sodium pole lighting, white stall lines clearly visible, painted directional arrows, low guardrail perimeter.
  7. Arrival reads as descending into a canyon — decks close in overhead.

6. Gaps / not yet measured

  • Deck heights above ground. OSM layer gives ordering, not elevation. Needs either a DEM lookup or estimation from video pier counts.
  • Third approach route. Confirmed to exist (video states "3 ways"); two are captured in full, the Honmoku run covers the approach only.
  • Exit ramp geometry. All captured footage is entry. Exits not yet sampled.
  • Stall grid angle. Aerial shows a diagonal ~40–45° grid; exact bearing not yet fitted.

7. Reproduce

python3 /tmp/osm_daikoku.py            # OSM geometry + circle fits
python3 /tmp/route.py <videoid> <name> <step_s>   # video -> contact sheets
python3 /tmp/sat.py                    # Esri aerial tiles
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