发出两个GPS坐标之间的计算指南针 [英] Issue with calcuating compass bearing between two GPS coordinates

问题描述

在我的web应用程序中，从包含1到n位置的经纬度坐标的数据库查询中获取JSON数据响应。我想计算从 data [i] 位置到当前位置的方位。

我已经修改此处的代码，但返回的方向不正确。

  //开始lat / long，并将lat转换为rads 
 var endLat = toRad（location.lat（））; 
 var endLong = location.lng（）; 
 
 //循环响应，计算链接的新标题并添加链接到数组
 for（var i = 0; i< data.length; i ++）{
 
 //此链接的纬度/经度坐标，将lat转换为rads 
 var startLat = toRad（data [i] .lat）; 
 var startLong = data [i] .lon; 
 
 //获得以rads开始和结束坐标之间的delta值
 var dLong = toRad（endLong  -  startLong）; 
 
 //计算
 var y = Math.sin（dLong）* Math.cos（endLong）; 
 var x = Math.cos（startLat）* Math.sin（endLat）-Math.sin（startLat）* Math.cos（endLat）* Math.cos（dLong）; 
 var bearing = Math.atan（y，x）; 
 bearing =（toDeg（bearing）+ 360）％360; $ {
 
 panoLinks.push（{'heading'：bearing，'description'：data [i] .description，'pano'：data [i] .description}）; 
} 
 
 //弧度/度转换
函数toRad（转换）{
返回转换* Math.PI / 180; 
} 
 
函数toDeg（convert）{
 return convert * 180 / Math.PI; 
 
 $ / code> 

使用上面的函数和值



  startLat = 43.6822，转换为0.7623982145146669弧度
 startLong = -70.450769 
 
 endLat = 43.682211，转换为0.7623984065008848弧度
 endLong = -70.45070 
 
 dLong = startLong  -  endLong，转换为0.0000011170107216805305弧度
  

导致指南针的程度为



  bearing = 0.000014910023935499339 
  

这绝对是关闭的。

解决方案

试试这个，我不能为了我的生活记得我在哪里尽管...



  / ** 
 *计算两个位置之间的方位为0-360 
 * 
 * @param lat1  - 第一个位置的纬度
 * @param lng1  - 第一个位置的经度
 * @param lat2  - 第二个位置的纬度
 * @param lng2  - 第二个位置的经度
 * 
 * @return int  -  0到360之间的方位
 * / 
方位：函数（lat1， lng1，lat2，lng2）{
 var dLon =（lng2-lng1）; 
 var y = Math.sin（dLon）* Math.cos（lat2）; 
 var x = Math.cos（lat1）* Math.sin（lat2） -  Math.sin（lat1）* Math.cos（lat2）* Math.cos（dLon）; 
 var brng = this._toDeg（Math.atan2（y，x））; 
 return 360  - （（brng + 360）％360）; 
 
 
 $ ** 
 *由于不是所有的浏览器都实现这个功能，我们有我们自己的实用程序，将
 *从度数转换为弧度
 * 
 * @param deg  - 要转换为弧度的度数
 * @return弧度
 * / 
 _toRad：函数（deg）{
 return deg * Math。 PI / 180; 
 
 
 $ ** 
 *由于不是所有的浏览器都实现这个功能，我们有自己的实用程序，将
 *从弧度转换为度数
 * 
 * @param rad  - 要转换为度数的弧度
 * @返回度
 * / 
 _toDeg：函数（rad）{
返回弧度* 180 / Math.PI; 
}，
  




In my webapp, have a JSON data response from a database query that includes the lat/long coordinates of 1 to n locations. I want to calculate the bearing from the data[i] location to the current position.

I've been adapting the code here, but the bearing returned is incorrect.

//starting lat/long along with converting lat to rads
var endLat = toRad(location.lat());        
var endLong = location.lng();

//loop over response, calculate new headings for links and add link to array
for(var i=0; i<data.length; i++){

  //this link's lat/long coordinates, convert lat to rads
  var startLat = toRad(data[i].lat);
  var startLong = data[i].lon;

  //get the delta values between start and end coordinates in rads
  var dLong = toRad(endLong - startLong);

  //calculate 
  var y = Math.sin(dLong)*Math.cos(endLong);
  var x = Math.cos(startLat)*Math.sin(endLat)-Math.sin(startLat)*Math.cos(endLat)*Math.cos(dLong);
  var bearing = Math.atan(y, x);
  bearing = (toDeg(bearing) + 360) % 360;

  panoLinks.push({'heading': bearing, 'description': data[i].description, 'pano': data[i].description});
}

//radian/degree conversions
function toRad(convert){
  return convert * Math.PI/180;
}

function toDeg(convert){
  return convert * 180/Math.PI;
}

Using the functions above and the values

startLat= 43.6822, converts to 0.7623982145146669 radians
startLong= -70.450769

endLat= 43.682211, converts to 0.7623984065008848 radians
endLong= -70.45070

dLong = startLong - endLong, converts to 0.0000011170107216805305 radians

results in a compass degree of

bearing= 0.000014910023935499339

which is definitely off. Where have I gone wrong?

解决方案

Give this a try, I can't for the life of me remember where I got it though...

    /**
     * Calculate the bearing between two positions as a value from 0-360
     *
     * @param lat1 - The latitude of the first position
     * @param lng1 - The longitude of the first position
     * @param lat2 - The latitude of the second position
     * @param lng2 - The longitude of the second position
     *
     * @return int - The bearing between 0 and 360
     */
    bearing : function (lat1,lng1,lat2,lng2) {
        var dLon = (lng2-lng1);
        var y = Math.sin(dLon) * Math.cos(lat2);
        var x = Math.cos(lat1)*Math.sin(lat2) - Math.sin(lat1)*Math.cos(lat2)*Math.cos(dLon);
        var brng = this._toDeg(Math.atan2(y, x));
        return 360 - ((brng + 360) % 360);
    },

   /**
     * Since not all browsers implement this we have our own utility that will
     * convert from degrees into radians
     *
     * @param deg - The degrees to be converted into radians
     * @return radians
     */
    _toRad : function(deg) {
         return deg * Math.PI / 180;
    },

    /**
     * Since not all browsers implement this we have our own utility that will
     * convert from radians into degrees
     *
     * @param rad - The radians to be converted into degrees
     * @return degrees
     */
    _toDeg : function(rad) {
        return rad * 180 / Math.PI;
    },

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