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October 10, 2017 06:25
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Calculate a random geo point on a circle radius
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| const R = 6371e3; // Earth radius in meters (approximated) | |
| const fromRadians = (rad) => rad / (Math.PI / 180); | |
| const toRadians = (deg) => deg * (Math.PI / 180); | |
| const getPointOnRadius = (center, radius, angle) => { | |
| const phi1 = toRadians(center.lat); | |
| const lambda1 = toRadians(center.lng); | |
| const theta = toRadians(angle); | |
| const d = radius; | |
| const phi2 = Math.asin( Math.sin(phi1)*Math.cos(d/R) + | |
| Math.cos(phi1)*Math.sin(d/R)*Math.cos(theta) ); | |
| const lambda2 = lambda1 + Math.atan2(Math.sin(theta)*Math.sin(d/R)*Math.cos(phi1), | |
| Math.cos(d/R)-Math.sin(phi1)*Math.sin(phi2)); | |
| return { | |
| lat: fromRadians(phi2), | |
| lng: (fromRadians(lambda2)+540)%360-180 | |
| }; | |
| } | |
| const center = { | |
| lat: 0, | |
| lng: 0 | |
| }; | |
| const angle = (Math.random() - 0.5) * 360; | |
| const distance = 1000; | |
| const point = getPointOnRadius(center, distance, angle); |
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