rijksdriehoektools/index.js

Some simple javascript tools for Rijksdriehoek conversions.

/**
 * Convert RD (Rijksdriehoek) coordinates to WGS84 and vice versa.
 * @see https://thomasv.nl/2014/03/rd-naar-gps/
 * Copied from @see https://gist.github.com/erikvullings/a2c58cecc3f0a27b043deba90089af57
 */
const x0 = 155000;
const y0 = 463000;
const f0 = 52.15517440; // f => phi
const l0 = 5.38720621;  // l => lambda

const Kp = [0, 2, 0, 2, 0, 2, 1, 4, 2, 4, 1];
const Kq = [1, 0, 2, 1, 3, 2, 0, 0, 3, 1, 1];
const Kpq = [
    3235.65389,
    -32.58297,
    -0.2475,
    -0.84978,
    -0.0655,
    -0.01709,
    -0.00738,
    0.0053,
    -0.00039,
    0.00033,
    -0.00012,
];

const Lp = [1, 1, 1, 3, 1, 3, 0, 3, 1, 0, 2, 5];
const Lq = [0, 1, 2, 0, 3, 1, 1, 2, 4, 2, 0, 0];
const Lpq = [
    5260.52916,
    105.94684,
    2.45656,
    -0.81885,
    0.05594,
    -0.05607,
    0.01199,
    -0.00256,
    0.00128,
    0.00022,
    -0.00022,
    0.00026,
];

const Rp = [0, 1, 2, 0, 1, 3, 1, 0, 2];
const Rq = [1, 1, 1, 3, 0, 1, 3, 2, 3];
const Rpq = [190094.945, -11832.228, -114.221, -32.391, -0.705, -2.34, -0.608, -0.008, 0.148];

const Sp = [1, 0, 2, 1, 3, 0, 2, 1, 0, 1];
const Sq = [0, 2, 0, 2, 0, 1, 2, 1, 4, 4];
const Spq = [309056.544, 3638.893, 73.077, -157.984, 59.788, 0.433, -6.439, -0.032, 0.092, -0.054];


/**
 * Convert RD x, y to WGS84 lat, lon.
 */
export function rdToWgs84(x, y = 0) {
    if (x instanceof Array) {
    y = x[1];
    x = x[0];
    } else if (typeof x !== 'number') {
    y = x.y;
    x = x.x;
    }
    const dX = 1e-5 * (x - x0);
    const dY = 1e-5 * (y - y0);

    let lat = 0;
    let lon = 0;

    for (let i = 0; i < 10; i++) {
    lat = lat + Kpq[i] * dX ** Kp[i] * dY ** Kq[i];
    }
    lat = f0 + lat / 3600;

    for (let i = 0; i < 11; i++) {
    lon = lon + Lpq[i] * dX ** Lp[i] * dY ** Lq[i];
    }
    lon = l0 + lon / 3600;

    return { lat, lon };
}

/**
 * Convert WGS84 lat, lon (or [lat, lon]) to RD x, y.
 */
export function wgs84ToRd(lat, lon = 0) {
    if (lat instanceof Array) {
        lon = lat[1];
        lat = lat[0];
    }
    const df = 0.36 * (lat - f0);
    const dl = 0.36 * (lon - l0);
    let x = x0;
    let y = y0;

    for (let i = 0; i < 8; i++) {
        x = x + Rpq[i] * df ** Rp[i] * dl ** Rq[i];
    }

    for (let i = 0; i < 9; i++) {
        y = y + Spq[i] * df ** Sp[i] * dl ** Sq[i];
    }

    return { x, y };
}