确定2个坐标之间的中点 [英] Determining Midpoint Between 2 Coordinates

问题描述

我试图确定MKMapView中两个位置之间的中点.我正在按照此处(和

I am trying to determine the midpoint between two locations in an MKMapView. I am following the method outlined here (and here) and rewrote it in Objective-C, but the map is being centered somewhere northeast of Baffin Island, which is no where near the two points.

我的方法基于上面链接的java方法:

My method based on the java method linked above:

+(CLLocationCoordinate2D)findCenterPoint:(CLLocationCoordinate2D)_lo1 :(CLLocationCoordinate2D)_loc2 {
    CLLocationCoordinate2D center;

    double lon1 = _lo1.longitude * M_PI / 180;
    double lon2 = _loc2.longitude * M_PI / 100;

    double lat1 = _lo1.latitude * M_PI / 180;
    double lat2 = _loc2.latitude * M_PI / 100;

    double dLon = lon2 - lon1;

    double x = cos(lat2) * cos(dLon);
    double y = cos(lat2) * sin(dLon);

    double lat3 = atan2( sin(lat1) + sin(lat2), sqrt((cos(lat1) + x) * (cos(lat1) + x) + y * y) );
    double lon3 = lon1 + atan2(y, cos(lat1) + x);

    center.latitude  = lat3 * 180 / M_PI;
    center.longitude = lon3 * 180 / M_PI;

    return center;
}

这两个参数具有以下数据:

The 2 parameters have the following data:

_loc1:
    latitude = 45.4959839
    longitude = -73.67826455

_loc2:
    latitude = 45.482889
    longitude = -73.57522299

以上内容正确放置在地图上(蒙特利尔及其周边地区).我试图将地图居中于2之间的中点，但我的方法返回以下内容:

The above are correctly place on the map (in and around Montreal). I am trying to center the map in the midpoint between the 2, yet my method return the following:

latitude = 65.29055
longitude = -82.55425

在北极某处，应该在南500英里左右.

which somewhere in the arctic, when it should be around 500 miles south.

推荐答案

只是预感，但是我注意到您的lon2和lat2变量是用M_PI/100而不是M_PI/180计算的.

Just a hunch, but I noticed your lon2 and lat2 variables are being computed with M_PI/100 and not M_PI/180.

double lon1 = _lo1.longitude * M_PI / 180;
double lon2 = _loc2.longitude * M_PI / 100;

double lat1 = _lo1.latitude * M_PI / 180;
double lat2 = _loc2.latitude * M_PI / 100;

将其更改为180可能会有所帮助.

Changing those to 180 might help you out a bit.

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