如何在没有谷歌地图的情况下计算边界中心？

Question

我有以下界限：

var bounds = {
    southwest: {lat: 54.69726685890506, lng: -2.7379201682812226},
    northeast: {lat: 55.38942944437183, lng: -1.2456105979687226}
};

通过使用 google 地图 API 我可以像下面这样计算上面边界的中心：

// returns (55.04334815163844, -1.9917653831249726)
(new google.maps.LatLngBounds(bounds.southeast, bounds.northeast)).getCenter();

如何在不使用 google.maps.LatLngBounds.getCenter 而使用数学的情况下计算边界中心？

我需要编写 "magic" 函数 returns 与 google.maps.LatLngBounds.getCenter:

相同的中心纬度、经度

function getBoundsCenter(bounds) {
    // need to calculate and return center of passed bounds;    
}

var center = getBoundsCenter(bounds); // center should be (55.04334815163844, -1.9917653831249726)

Answer 1

var bounds = {
    southwest: {lat: 54.69726685890506, lng: -2.7379201682812226},
    northeast: {lat: 55.38942944437183, lng: -1.2456105979687226}
};

center lat = (southwest.lat + northeast.lat)/2 = 55.043348151638
center lng = (southwest.lng + northeast.lng)/2 = -1.991765383125

如果您需要跨越国际日期变更线：

如果两个经度之间的差异大于 180 度，则将范围从 -180 到 +180 移动到 0 到 360，方法是将 360 加到每个数字上以 360 为模：

  if ((bounds.southwest.lng - bounds.northeast.lng > 180) || 
      (bounds.northeast.lng - bounds.southwest.lng > 180))
  {
    bounds.southwest.lng += 360;
    bounds.southwest.lng %= 360;
    bounds.northeast.lng += 360;
    bounds.northeast.lng %= 360;
  }

proof of concept fiddle（在 Google 地图 Javascript API v3 地图上显示结果，但不需要 API）

代码片段：：

console.log("original bounds in question");
var bounds = {
  southwest: {
    lat: 54.69726685890506,
    lng: -2.7379201682812226
  },
  northeast: {
    lat: 55.38942944437183,
    lng: -1.2456105979687226
  }
};

if ((bounds.southwest.lng - bounds.northeast.lng > 180) || (bounds.northeast.lng - bounds.southwest.lng > 180)) {
  bounds.southwest.lng += 360;
  bounds.southwest.lng %= 360;
  bounds.northeast.lng += 360;
  bounds.northeast.lng %= 360;
}
var center_lat = (bounds.southwest.lat + bounds.northeast.lat) / 2; // = 55.043348151638
console.log("center_lat=" + center_lat);
var center_lng = (bounds.southwest.lng + bounds.northeast.lng) / 2; // = -1.991765383125
console.log("center_lng=" + center_lng);

console.log("bounds in crossing International Date Line");
var bounds = {
  southwest: {
    lat: 54.69726685890506,
    lng: -182.7379201682812226
  },
  northeast: {
    lat: 55.38942944437183,
    lng: 181.2456105979687226
  }
};

if ((bounds.southwest.lng - bounds.northeast.lng > 180) || (bounds.northeast.lng - bounds.southwest.lng > 180)) {
  bounds.southwest.lng += 360;
  bounds.southwest.lng %= 360;
  bounds.northeast.lng += 360;
  bounds.northeast.lng %= 360;
}
var center_lat = (bounds.southwest.lat + bounds.northeast.lat) / 2; // = 55.043348151638
console.log("center_lat=" + center_lat);
var center_lng = (bounds.southwest.lng + bounds.northeast.lng) / 2; // = -1.991765383125
console.log("center_lng=" + center_lng);

如何在没有谷歌地图的情况下计算边界中心？

How to calculate center of bounds without GoogleMaps?

google-maps

latitude-longitude

bounds