Math formula for transforming from EPSG:4326 to EPSG:3857

Question

Is there any math formula for transforming from EPSG:4326 to EPSG:3857 ?
i want to implement it in php code

nickves · Accepted Answer

Projection EPSG:3857 uses the method EPSG:1024 for Forward and Reverse calculations.
The method is fully documented at Geomatics Guidance Note No 7, part 2
There's an mathematical example at page 40 where you can use to cross-reference your code.
17/11/2020 EDIT: The link to the above documentation from times to times, gets broken as things evolve. If that happens please feel free to update it as necessary.

user144482 · Answer

I got a C# code for using in unity engine.

Here the code below :

public static double[] latLonToMeters(double lat, double lon)
{
    //Debug.Log(Mathd.Tan((90d + lat) * Mathd.PI / 720));
    //Debug.Log(Mathd.Tan((90d + lat) * Mathd.PI / 360d));
    double[] meters = new double[2];
    meters[0] = lat * originShift / 180d;
    meters[1] = Mathd.Log(Mathd.Tan((90d+lon) * Mathd.PI / 360d)) / (Mathd.PI / 180d);
    //meters[1] = Mathd.Log(5) / (Mathd.PI / 180d);
    meters[1] = meters[1] * originShift / 180d;
    return meters;
}

neubert · Answer

PHP code:
function convert4326to3857($x, $y)
{
    return [
        $x * 180 / 20037508.34,
        atan(exp($y / 111319.490778 * pi() / 180)) * 360 / pi() - 90
    ];
}

Math formula for transforming from EPSG:4326 to EPSG:3857

3 Answers

Add your own answers!

Ask a Question