GPS纠偏算法

GPS纠偏算法

本文提供的GPS纠偏算法，根据某一篇Java纠偏博文修改完善为C#语言支持。

最近自己做地图相关项目，遇到坐标偏移。众所周知，在国内，GPS数据无法直接在瓦片服务器获取准确瓦片，通过查找比对修改，还原了了纠偏相关算法。

效果还是比较明显的

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源代码

相关代码如下：

using System;

namespace MapTest
{
    /// 

    /// 纠偏
    /// Rectify deviation
    /// GPS纠偏算法，适用于google,高德体系的地图
    /// 
    public class RD
    {
        private static double Pi = 3.14159265358979324;
        private static double A = 6378245.0;
        private static double Ee = 0.00669342162296594323;

        public static void Transform(double wgLat, double wgLon, ref double[] latlng)
        {
            if (OutOfChina(wgLat, wgLon))
            {
                latlng[0] = wgLat;
                latlng[1] = wgLon;
                return;
            }
            double dLat = TransformLat(wgLon - 105.0, wgLat - 35.0);
            double dLon = TransformLon(wgLon - 105.0, wgLat - 35.0);
            double radLat = wgLat / 180.0 * Pi;
            double magic = Math.Sin(radLat);
            magic = 1 - Ee * magic * magic;
            double sqrtMagic = Math.Sqrt(magic);
            dLat = (dLat * 180.0) / ((A * (1 - Ee)) / (magic * sqrtMagic) * Pi);
            dLon = (dLon * 180.0) / (A / sqrtMagic * Math.Cos(radLat) * Pi);
            latlng[0] = wgLat + dLat;
            latlng[1] = wgLon + dLon;
        }

        private static bool OutOfChina(double lat, double lon)
        {
            if (lon < 72.004 || lon > 137.8347)
                return true;
            if (lat < 0.8293 || lat > 55.8271)
                return true;
            return false;
        }

        private static double TransformLat(double x, double y)
        {
            double ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.Sqrt(Math.Abs(x));
            ret += (20.0 * Math.Sin(6.0 * x * Pi) + 20.0 * Math.Sin(2.0 * x * Pi)) * 2.0 / 3.0;
            ret += (20.0 * Math.Sin(y * Pi) + 40.0 * Math.Sin(y / 3.0 * Pi)) * 2.0 / 3.0;
            ret += (160.0 * Math.Sin(y / 12.0 * Pi) + 320 * Math.Sin(y * Pi / 30.0)) * 2.0 / 3.0;
            return ret;
        }

        private static double TransformLon(double x, double y)
        {
            double ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.Sqrt(Math.Abs(x));
            ret += (20.0 * Math.Sin(6.0 * x * Pi) + 20.0 * Math.Sin(2.0 * x * Pi)) * 2.0 / 3.0;
            ret += (20.0 * Math.Sin(x * Pi) + 40.0 * Math.Sin(x / 3.0 * Pi)) * 2.0 / 3.0;
            ret += (150.0 * Math.Sin(x / 12.0 * Pi) + 300.0 * Math.Sin(x / 30.0 * Pi)) * 2.0 / 3.0;
            return ret;
        }
    }
}

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2018年8月3日
Dawn