谷歌地圖：從已知的起始位置獲取緯度/經度公里

Question

假設我知道公路A的起始緯度/經度，並且建築區域從公里175開始。 有沒有辦法計算緯度/經度在175公里處？ （可能與方向服務）

Answer 1

Mike Williams寫了一個擴展名爲Google Maps Javascript API v2 (now deprecated and turned off)其中epoly包含方法.GetPointAtDistance，這你想要做什麼。所述GetPointAtDistance功能的

example using a ported version of that library

部分源代碼（取決於延伸與distanceFrom方法google.maps.LatLng對象）

/* .GetPointAtDistance() returns a google.maps.LatLng at the specified distance * 
*     along the path.            * 
*     The distance is specified in metres       * 
*     Returns null if the path is shorter than that    * 
*/ 

// === A method which returns a google.maps.LatLng of a point a given distance along the path === 
// === Returns null if the path is shorter than the specified distance === 
google.maps.Polygon.prototype.GetPointAtDistance = function(metres) { 
    // some awkward special cases 
    if (metres == 0) return this.getPath().getAt(0); 
    if (metres < 0) return null; 
    if (this.getPath().getLength() < 2) return null; 
    var dist=0; 
    var olddist=0; 
    for (var i=1; (i < this.getPath().getLength() && dist < metres); i++) { 
    olddist = dist; 
    dist += this.getPath().getAt(i).distanceFrom(this.getPath().getAt(i-1)); 
    } 
    if (dist < metres) { 
    return null; 
    } 
    var p1= this.getPath().getAt(i-2); 
    var p2= this.getPath().getAt(i-1); 
    var m = (metres-olddist)/(dist-olddist); 
    return new google.maps.LatLng(p1.lat() + (p2.lat()-p1.lat())*m, p1.lng() + (p2.lng()-p1.lng())*m); 
}