经纬度计算

mysql数据库计算

#公式如下，单位米：
#第一点经纬度：lng1 lat1
#第二点经纬度：lng2 lat2
#round(6378.138*2*asin(sqrt(pow(sin((lat1*pi()/180-lat2*pi()/180)/2),2)+cos(lat1*pi()/180)*cos(lat2*pi()/180)*pow(sin( (lng1*pi()/180-lng2*pi()/180)/2),2)))*1000)
 

#列如
SET @lat = 30.699799;
SET @lng = 104.063393;
SELECT id, 
round(6378.138*2*asin(sqrt(pow(sin((lat*pi()/180-@lat*pi()/180)/2),2)+cos(lat*pi()/180)*cos(@lat*pi()/180)*pow(sin( (lng*pi()/180-@lng*pi()/180)/2),2)))*1000) AS distance 
FROM markers HAVING distance < 1000 ORDER BY distance;

.NET计算

        private static readonly double EARTH_RADIUS = 6378.137;//地球半径

        /// <summary>
        /// 根据提供的两个经纬度计算距离(米)
        /// </summary>
        /// <param name="lng1">经度1</param>
        /// <param name="lat1">纬度1</param>
        /// <param name="lng2">经度2</param>
        /// <param name="lat2">纬度2</param>
        /// <returns></returns>
        public static double GetDistance(double lat1, double lng1, double lat2, double lng2)
        {
            double radLat1 = rad(lat1);
            double radLat2 = rad(lat2);
            double a = radLat1 - radLat2;
            double b = rad(lng1) - rad(lng2);

            double s = 2 * Math.Asin(Math.Sqrt(Math.Pow(Math.Sin(a / 2), 2) +
             Math.Cos(radLat1) * Math.Cos(radLat2) * Math.Pow(Math.Sin(b / 2), 2)));
            s = s * EARTH_RADIUS;
            s = Math.Round(s * 10000) / 10000;
            return s * 1000;
        }

        private static double rad(double d)
        {
            return d * Math.PI / 180.0;
        }