计算端点给定距离，方位，起点

我试图找到目的地点，给定起点纬度/长度，方位和距离。 下面这个网站的计算器给了我想要的结果。

http://www.movable-type.co.uk/scripts/latlong.html

当我尝试通过代码实现相同的操作时，我得不到正确的结果。

以下是我的代码 –

private GLatLng pointRadialDistance(double lat1, double lon1, double radianBearing, double radialDistance) { double rEarth = 6371.01; lat1 = DegreeToRadian(lat1); lon1 = DegreeToRadian(lon1); radianBearing = DegreeToRadian(radianBearing); radialDistance = radialDistance / rEarth; double lat = Math.Asin(Math.Sin(lat1) * Math.Cos(radialDistance) + Math.Cos(lat1) * Math.Sin(radialDistance) * Math.Cos(radianBearing)); double lon; if (Math.Cos(lat) == 0) { // Endpoint a pole lon = lon1; } else { lon = ((lon1 - Math.Asin(Math.Sin(radianBearing) * Math.Sin(radialDistance) / Math.Cos(lat)) + Math.PI) % (2 * Math.PI)) - Math.PI; } lat = RadianToDegree(lat); lon = RadianToDegree(lon); GLatLng newLatLng = new GLatLng(lat, lon); return newLatLng; } public double Bearing(double lat1, double long1, double lat2, double long2) { //Convert input values to radians lat1 = DegreeToRadian(lat1); long1 = DegreeToRadian(long1); lat2 = DegreeToRadian(lat2); long2 = DegreeToRadian(long2); double deltaLong = long2 - long1; double y = Math.Sin(deltaLong) * Math.Cos(lat2); double x = Math.Cos(lat1) * Math.Sin(lat2) - Math.Sin(lat1) * Math.Cos(lat2) * Math.Cos(deltaLong); double bearing = Math.Atan2(y, x); return bearing; } public double DegreeToRadian(double angle) { return Math.PI * angle / 180.0; } public double RadianToDegree(double angle) { return 180.0 * angle / Math.PI; } 

从主程序，我调用子程序如下 –

 double bearing = Bearing(-41.294444, 174.814444, -40.90521, 175.6604); GLatLng endLatLng = pointRadialDistance(-41.294444, 174.814444, bearing, 80); 

我得到以下结果 –

 Bearing=1.02749621782165 endLatLng=-40.5751022737927,174.797458881699 

我期待的答案是-40.939722,175.646389 （来自上面的网站链接）。

任何人都可以建议我在这里的代码中犯了什么错误？

Answer 1

这里有一些代码可以实现您想要做的事情。

 public static GeoLocation FindPointAtDistanceFrom(GeoLocation startPoint, double initialBearingRadians, double distanceKilometres) { const double radiusEarthKilometres = 6371.01; var distRatio = distanceKilometres / radiusEarthKilometres; var distRatioSine = Math.Sin(distRatio); var distRatioCosine = Math.Cos(distRatio); var startLatRad = DegreesToRadians(startPoint.Latitude); var startLonRad = DegreesToRadians(startPoint.Longitude); var startLatCos = Math.Cos(startLatRad); var startLatSin = Math.Sin(startLatRad); var endLatRads = Math.Asin((startLatSin * distRatioCosine) + (startLatCos * distRatioSine * Math.Cos(initialBearingRadians))); var endLonRads = startLonRad + Math.Atan2( Math.Sin(initialBearingRadians) * distRatioSine * startLatCos, distRatioCosine - startLatSin * Math.Sin(endLatRads)); return new GeoLocation { Latitude = RadiansToDegrees(endLatRads), Longitude = RadiansToDegrees(endLonRads) }; } public struct GeoLocation { public double Latitude { get; set; } public double Longitude { get; set; } } public static double DegreesToRadians(double degrees) { const double degToRadFactor = Math.PI / 180; return degrees * degToRadFactor; } public static double RadiansToDegrees(double radians) { const double radToDegFactor = 180 / Math.PI; return radians * radToDegFactor; } 

Answer 2

几何库（V3）中非常简单的解决方案，如果你没有使用google maps api V3的问题（例如，取决于应用程序 – 实时资产跟踪 – 免费许可证不适用或者你可能不想重构从V2到V3）。

1st：使用您当前的声明声明一个额外的库ALONG：

第二：建立起点，航向和距离

 var nyc = new google.maps.LatLng(40.715, -74.002); var distance = 5576673; var heading = 51.2145; 

第3名：去那儿

 var endPoint = google.maps.geometry.spherical.computeOffset(nyc, distance, heading); var london = new google.maps.Marker({ position: endPoint, map: map }); 

完了，你现在在伦敦小镇。 有关computeDistance，computeHeading和computeArea的更多信息：

http://www.svennerberg.com/2011/04/calculating-distances-and-areas-in-google-maps-api-3/

http://code.google.com/intl/en/apis/maps/documentation/javascript/geometry.html

Answer 3

下面是http://www.movable-type.co.uk/scripts/latlong.html上的JavaScript代码的实现，我自己编写并在我自己的项目中使用。 如果愿意，您可以将其实施到您的项目中。

注意：坐标是具有X（经度），Y（纬度），Z（高度）属性的类。 ToDegree（）和ToRadian（）是Double类型的扩展。 最后，GetTarget（）是Coordinate实例的扩展。

 /// 
Calculates the destination coordinate by given angle and distance.
 /// Origin. /// Azimuth. /// Distance (km). /// Coordinate. public static Coordinate GetTarget( this Coordinate origin, double bearing, double distance, double altitude = 0) { var d = distance / 6371; var rlat = origin.Y.ToRadian(); var rlon = origin.X.ToRadian(); var rbearing = bearing.ToRadian(); var lat2 = rlat + (d * Math.Cos(rbearing)); var dlat = lat2 - rlat; var dphi = Math.Log((Math.Tan((lat2 / 2) + (Math.PI / 4))) / (Math.Tan((rlat / 2) + (Math.PI / 4)))); var q = Math.Abs(dlat) > 0.0000000001 ? dlat / dphi : Math.Cos(rlat); var dlon = (d * Math.Sin(rbearing)) / q; if (Math.Abs(lat2) > Math.PI / 2) { lat2 = lat2 > 0 ? Math.PI : Math.PI - lat2; } var lon2 = (rlon + dlon + Math.PI) % (2 * Math.PI) - Math.PI; return new Coordinate { X = lon2.ToDegree(), Y = lat2.ToDegree(), Z = origin.Z }; }