Every measured flight, ping, rail line and satellite pass on one plane
Rule. The surface is a plane. Each of the {{N_CITIES}} cities may sit anywhere on it. No latitude, longitude, radius, projection or spherical formula enters the solver.
Measurements. Flight times give lengths: {{N_FLIGHTS}} routes, cruise speed × time in the air, both directions. Pings ({{N_RT}}), rail and road lengths ({{N_RAIL}}) and satellite passes ({{N_SAT}}) give limits: no farther apart than this.
Tolerance. A flight holds between {{LO_PCT}}% and {{HI_PCT}}% of its length. Shorter means a route over a third longer than the straight line; longer means an aircraft above its top speed the whole way.
Solver. The page opens on a starting flat map as drawn. Solve moves the cities to keep as many measurements as it can and marks the rest red (faster than possible) or amber (far off the straight line). Coastlines follow the cities like a rubber sheet.
Best of {{N_STARTS}} starting maps (North-pole and dual-pole AE, the layout of the flight times alone, and AE maps centred on {{N_STARTS_AE}} other points): {{BEST_BROKEN}} measurements broken. The plane keeps almost the whole northern network, but it cannot close the ring of routes around the southern oceans: {{LONG_LIST}}. Each of those needs its aircraft faster than it can fly. To keep the rest, the plane squeezes {{BEST_B80}} flights below 80% of their timed length; on the globe {{GLOBE_B80}} are.
On the globe, by the same rules: {{GLOBE_LONG}} flight longer than its aircraft can fly (San Salvador–San José, a short hop where the 15-minute allowance for climb and descent is too generous), {{GLOBE_LIM}} limits broken, and {{GLOBE_SHORT}} flights below {{LO_PCT}}%: detours around closed airspace, indirect airways, and short hops where climb and approach take most of the time ({{GLOBE_SHORT_LIST}}). Surveyed triangles do not depend on the layout: a plane gives every triangle exactly 180°, and {{TRI_FLAT}} of the {{N_TRI}} measured triangles exceed that by more than four times their survey's angle noise ({{TRI_GLOBE}} on the globe; The Triangle Test).
Released into 3D, the same cities and measurements close into a ball. The cities wrap {{WRAP3}}° round its centre, with {{BROKEN3}} measurements broken. Measured along a sphere instead, with the shape conceded and its size left free (Measure along a sphere, above), the flights fit a sphere of radius {{ARC_R}} km with {{ARC_BROKEN}} measurements broken, and the cities fall a median {{ARC_OFF}} km from their true places. Earth's mean radius is 6,371 km; routes flown run slightly longer than the shortest path.
The further short a flight may fall, the more of the network the plane can squeeze to make room for the southern routes. It keeps everything once flights may fall to {{FIT_LO}}% of their timed length, which means routes up to twice as long as its straight lines. That layout has {{FIT_B75}} flights below 75% and {{FIT_B60}} below 60%. The globe has {{GLOBE_B75}} and {{GLOBE_B60}}.
| Flights kept between | Plane: too long | Plane: too short | Plane: limits | Plane: below 75% | Globe: too long | Globe: too short | Globe: limits |
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A ping only caps a distance, and internet routes run well past the straight line, so the caps are loose. With pings alone a flat map can shrink until every cap holds; turn off Flight times to see it. Scale comes from lengths, and the flights supply them.
fit.py) ran from {{N_STARTS}} starting maps and then refined the 20 best layouts with twelve rounds.