衛星の軌道をWeb地図上に表示する

FOSS4G LT会 #002 資料

イベント詳細: https://osgeojp.connpass.com/event/350766/
リポジトリ: https://github.com/sankichi92/react-sat-map

Transcript

1. 
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3. HJUIVCDPNTBOLJDIJSFBDUTBUNBQ w يಓ৘ใΛ΋ͱʹӴ੕ͷ
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   يಓΛදࣔ͢ΔػೳΛ௥Ճ SFBDUTBUNBQ 
4. σϞ
5. يಓදࣔ
   W TBUFMMJUFKT
   ʹΑΔيಓ఻೻ import { degreesLat, degreesLong, eciToGeodetic, gstime, propagate, SatRec } from "satellite.js"; export function getLineCoordinates(satrec: SatRec, date: Date) { const orbitDuration = ((2 * Math.PI) / satrec.no) * 60; // 1पճ෼ʹ͔͔Δ࣌ؒ const step = orbitDuration / 360 // يಓΛे෼׈Β͔ʹදࣔͰ͖Δεςοϓ਺ (360) Ͱ෼ׂ // ֤࣌఺Ͱͷ࠲ඪΛܭࢉ const coordinates: [number, number][] = []; for (let elapsed = 0; elapsed < orbitDuration; elapsed += step) { const stepDate = new Date(date.getTime() + elapsed * 1000); const location = getSatelliteLocation(satrec, stepDate); if (!location) break; coordinates.push(location); } return coordinates; } function getSatelliteLocation(satrec: SatRec, date: Date) { const result = propagate(satrec, date); if (!result) return null; const { longitude, latitude } = eciToGeodetic(result.position, gstime(date)); return [degreesLong(longitude), degreesLat(latitude)] as [number, number]; } 
7. ౓ܦઢΛ·ͨ͛ͳ͍
8. NBQMJCSFPSHNBQMJCSFHMKTEPDTFYBNQMFTMJOF BDSPTTUINFSJEJBO w TBUFMMJUFKT
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   w Ң౓ܦ౓ʹม׵͢Δͱܦ౓ͷ
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   ͱ
   
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   ੢͔Β౦ʹ݁Ϳʹ͸
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   ౦͔Β੢ʹ݁Ϳʹ͸
   ˠ
   ͷॱʹ͢Δඞཁ͕͋Δ ౓ܦઢΛ·͙ͨ 
9. يಓදࣔ
   W ౓ܦઢΛ·͍ͨͰيಓΛ݁Ϳ function adjustLongitude(longitude: number, prevLongitude: number) { if (longitude - prevLongitude > 180) { // ੢͔Β౦΁180౓ܦઢΛ·͙ͨ৔߹ return longitude - 360; } else if (longitude - prevLongitude < -180) { // ౦͔Β੢΁180౓ܦઢΛ·͙ͨ৔߹ return longitude + 360; } else { return longitude; } } 
11. ΍͔ͬͨʂʁ
13. ౓ܦઢΛճ·͙ͨͱμϝ
14. يಓදࣔ
    W ౓ܦઢΛճҎ্·ͨ͛ΔΑ͏ʹ͢Δ function adjustLongitude(longitude: number, prevLongitude: number) { // prevLongitude ͕ -360/360 Λ௒͍͑ͯΔ৔߹͸पճΛ߹ΘͤΔ let adjusted = longitude + Math.trunc(prevLongitude / 360) * 360; if (adjusted - prevLongitude > 180) { return adjusted - 360; } else if (adjusted - prevLongitude < -180) { return adjusted + 360; } else { return adjusted; } } 
15. يಓͷܭࢉ݁ՌΛΩϟογϡ͢Δ w ͢Ͱʹܭࢉͨ͠يಓΛը໘ඳը͝ͱ ʹ࠶ܭࢉ͢Δͷ͸ແବ
    w يಓͷܭࢉ݁ՌΛΩϟογϡ
    W
    w ͢Δͱલճͷঢ়ଶ͕࢒͍ͬͯΔͷͰ
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    w ि͝ͱʹՃݮࢉͯ͠मਖ਼
    W يಓදࣔ
    W
    W 
16. 
    !TBOLJDIJ ౓ܦઢͱͷઓ͍
    Ӵ੕ͷيಓΛ8FC஍ਤ্ʹදࣔ͢Δ '044(
    -5ձ