GPS获取坐标 显示Google map偏差计算
用手机获取GPS坐标 显示在手机地图偏差大约在100-200米左右,我把坐标放在 Maps.google.com 搜索坐标定位则相当精确。
可能是.....为了安全吧故意加的偏差
不过可以计算偏差使位置精确
代码如下
public class EvilTransform { static double pi = 3.14159265358979324; static double a = 6378245.0; static double ee = 0.00669342162296594323; public static double mgLat; public static double mgLon; public static void transform( double wgLat, double wgLon) { if (outOfChina(wgLat, wgLon)) { mgLat = wgLat; mgLon = 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); mgLat = wgLat + dLat; mgLon = wgLon + dLon; } static Boolean 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; } 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; } 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; } }