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86 lines
3.7 KiB
JavaScript
86 lines
3.7 KiB
JavaScript
// src/data/routePlausible.js
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/**
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* Is an adsbdb scheduled route consistent with where the plane actually is and
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* what it is doing? adsbdb returns the scheduled route for a callsign, which
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* is sometimes the wrong leg — reject a route rather than display a wrong one.
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* Adapted from skylight (MIT) web/src/display/renderer.ts routePlausible(),
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* with the vertical-trend check made observer-free (skylight anchors it to a
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* fixed ground station; GEV has no observer, so the check is anchored to the
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* PLANE: climbing hard + low → its origin should be nearby; descending hard +
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* low → its destination should be nearby).
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*/
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const D2R = Math.PI / 180;
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const R_KM = 6371;
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/** Haversine great-circle distance in km. */
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export function greatCircleKm(lat1, lon1, lat2, lon2) {
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const p1 = lat1 * D2R;
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const p2 = lat2 * D2R;
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const dp = (lat2 - lat1) * D2R;
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const dl = (lon2 - lon1) * D2R;
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const a = Math.sin(dp / 2) ** 2 + Math.cos(p1) * Math.cos(p2) * Math.sin(dl / 2) ** 2;
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return R_KM * 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
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}
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function bearingRad(lat1, lon1, lat2, lon2) {
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const p1 = lat1 * D2R;
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const p2 = lat2 * D2R;
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const dl = (lon2 - lon1) * D2R;
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const y = Math.sin(dl) * Math.cos(p2);
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const x = Math.cos(p1) * Math.sin(p2) - Math.sin(p1) * Math.cos(p2) * Math.cos(dl);
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return Math.atan2(y, x);
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}
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/** Signed cross-track distance (km) of point from the great circle p1→p2. */
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export function crossTrackKm(lat, lon, lat1, lon1, lat2, lon2) {
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const d13 = greatCircleKm(lat1, lon1, lat, lon) / R_KM;
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const b13 = bearingRad(lat1, lon1, lat, lon);
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const b12 = bearingRad(lat1, lon1, lat2, lon2);
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return Math.asin(Math.sin(d13) * Math.sin(b13 - b12)) * R_KM;
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}
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const NEAR_ENDPOINT_KM = 130;
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const CROSS_TRACK_KM = 200;
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const LOW_ALT_M = 3700; // ~12 000 ft
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const VERT_TREND_MPS = 2; // ~400 fpm
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const LOCAL_AIRPORT_KM = 150;
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/**
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* @param {object} p
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* @param {number} p.latDeg / p.lonDeg — plane's current position
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* @param {number|null} [p.altitudeM]
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* @param {number|null} [p.verticalRateMps] — positive = climbing
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* @param {{lat:number|null, lon:number|null}|null} [p.origin]
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* @param {{lat:number|null, lon:number|null}|null} [p.destination]
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* @returns {boolean} false ONLY when the route is confidently wrong.
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*/
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export function routePlausible({ latDeg, lonDeg, altitudeM = null, verticalRateMps = null, origin = null, destination = null }) {
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const haveO = Number.isFinite(origin?.lat) && Number.isFinite(origin?.lon);
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const haveD = Number.isFinite(destination?.lat) && Number.isFinite(destination?.lon);
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if (!haveO && !haveD) return true; // no coordinates — cannot judge, do not hide
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// (a) Geographic consistency: near an endpoint, or roughly on the path.
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const near = (pt) => greatCircleKm(latDeg, lonDeg, pt.lat, pt.lon) < NEAR_ENDPOINT_KM;
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let geomOk = (haveO && near(origin)) || (haveD && near(destination));
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if (!geomOk && haveO && haveD) {
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geomOk = Math.abs(crossTrackKm(latDeg, lonDeg, origin.lat, origin.lon, destination.lat, destination.lon)) < CROSS_TRACK_KM;
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} else if (!geomOk) {
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geomOk = true; // only one endpoint known and not near — cannot judge, allow
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}
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if (!geomOk) return false;
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// (b) Vertical-trend consistency for low traffic (observer-free adaptation).
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if (
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Number.isFinite(altitudeM) && altitudeM < LOW_ALT_M &&
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Number.isFinite(verticalRateMps) && Math.abs(verticalRateMps) > VERT_TREND_MPS
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) {
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if (verticalRateMps > 0) {
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if (haveO && greatCircleKm(latDeg, lonDeg, origin.lat, origin.lon) > LOCAL_AIRPORT_KM) return false; // departing — origin should be local
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} else {
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if (haveD && greatCircleKm(latDeg, lonDeg, destination.lat, destination.lon) > LOCAL_AIRPORT_KM) return false; // arriving — destination should be local
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}
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}
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return true;
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}
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