2077-gps-mod/docs/gps-momentum-field-tests.md

GPS Momentum Field Tests

Current patch surface: fixed additive penalty on ordinary GPS solver edge expansion, patched at the two ordinary relaxation callsites feeding 0x40ba58. Live tuning is through momentum_weights.bin.

2026-06-27 North Watson To Dogtown/Badlands

Starting context: player in North Watson near the motel/Cassius area. The two main comparison routes fit in the same map viewport:

• The Damned / Dogtown, south into Pacifica.
• Fuel Station fast travel point in the southwest Badlands/Biotechnica flats.

Screenshots:

• logs/screenshots/the-damned-and-fuel-station-0.webp
• logs/screenshots/the-damned-and-fuel-station-8.webp
• logs/screenshots/the-damned-and-fuel-station-80.webp

Telemetry log:

• logs/EdgeWeightGPS_live_momentum_ab_8_0_80.log

Results:

Route	Penalty	Expansion calls	Route records	Observed route
The Damned	8	1,057,410	78	Similar to vanilla; threads city blocks and a side highway.
The Damned	0	1,110,243	87	Similar visible corridor, slightly more route-record churn.
The Damned	80	1,010,035	70	Visibly smoother highway corridor, avoids City Center stair-stepping.
Fuel Station	8	296,976	89	Uses City Center roundabout/city threading.
Fuel Station	0	about 308k-314k	90-92	Similar visible corridor to 8.
Fuel Station	80	about 345k-347k	77-78	Converges onto the smoother highway corridor before splitting south.

Interpretation:

• 0 and 8 are close visually in this location, despite small telemetry changes.
• 80 is a strong proof value: it changes the coarse corridor and reduces route-record count for the tested long routes.
• This supports the main hypothesis that a fixed per-segment additive penalty can optimize for smoother player-driving corridors, not merely highway class.

2026-06-27 Broad 80 Smoke

Telemetry log:

• logs/EdgeWeightGPS_momentum80_broad_smoke.log
• logs/EdgeWeightGPS_momentum80_drive_validation.log

User reported no bad routes after probing:

• Claire routes differently than nearby Sinnerman, choosing a smooth Japantown highway leg.
• Sinnerman still cuts through City Center, plausibly because that corridor is appropriate for that destination.
• Short local routing to Cassius remains fine.
• Heywood routes remain fine and may avoid some stair-stepping.
• Routes near highways but not traffic-feasible still detour appropriately.
• One NCPD bounty used a road the user had not previously seen GPS select, and it looked like a good fit.

Interpretation:

• No obvious local-route breakage was found at 80.
• 80 was not immediately pathological in the sampled routes and later became the working default after drive validation.
• Higher values still need caution; 160 later proved too high.

Drive validation at 80:

• The Damned / Dogtown route drove cleanly in the Outlaw at sustained high speed.
• The route surfaced a back/elevated highway through Japantown/Westbrook that the user had not seen vanilla GPS select before.
• Live minimap recalculation after a deliberate detour still worked.
• Claire route also drove cleanly. One ramp/hill surprised the driver, but the issue was road unfamiliarity at full speed, not bad routing.

Conclusion after the drive test: 80 is the working default.

2026-06-27 40/160 Bounds

Telemetry log:

• logs/EdgeWeightGPS_momentum40_160_tuning.log

At 40, the highlighted routes improved only partially:

• Claire still used the Sinnerman/City Center path instead of the smoother outer road.
• Sinnerman remained sensible.
• The near-highway case remained acceptable.
• The NCPD bounty took the smoother outer City Center road, but retained a Watson stair-step that 80 avoided.

At 160, overcorrection appeared:

• Claire showed a questionable hairpin.
• The Damned produced a fallback/straight-line style route instead of a usable road route.
• The Gig/Cassius local access got worse, asking for a backtrack and hairpin instead of a simple nearby approach.
• NCPD bounty regressed to stair-stepping.

Conclusion: 160 is too high. The useful bracket is roughly 40 < default < 160, with 80 currently best validated by map inspection and driving.