我将使用C#计算可用Lat/Lng列表的中心点并在OpenLayer地图上呈现。
我注意到获取中心点Lat/Lng的计算会给我略微不同的Lat/Lng。我参考了这个链接进行计算 Calculate the center point of multiple latitude/longitude coordinate pairs.
C# 代码:
static void Main(string[] args)
{
List<GeoCoordinate> listCoordinate = new List<GeoCoordinate>();
listCoordinate.Add(new GeoCoordinate() { Latitude = 22.9833, Longitude = 72.5000 }); //Sarkhej
listCoordinate.Add(new GeoCoordinate() { Latitude = 18.9750, Longitude = 72.8258 }); //Mumbai
listCoordinate.Add(new GeoCoordinate() { Latitude = 22.3000, Longitude = 73.2003 }); //Vadodara
listCoordinate.Add(new GeoCoordinate() { Latitude = 26.9260, Longitude = 75.8235 }); //Jaipur
listCoordinate.Add(new GeoCoordinate() { Latitude = 28.6100, Longitude = 77.2300 }); //Delhi
listCoordinate.Add(new GeoCoordinate() { Latitude = 22.3000, Longitude = 70.7833 }); //Rajkot
GeoCoordinate centerCoordinate = GetCentralGeoCoordinate(listCoordinate); //Output (Latitude:23.696708071960074, Longitude:73.681549202080149)
Console.WriteLine("Lat:" + centerCoordinate.Latitude + ",Lon:" + centerCoordinate.Longitude);
Console.ReadKey();
}
public static GeoCoordinate GetCentralGeoCoordinate(List<GeoCoordinate> geoCoordinates)
{
if (geoCoordinates.Count == 1)
{
return geoCoordinates.Single();
}
double x = 0, y = 0, z = 0;
foreach (var geoCoordinate in geoCoordinates)
{
var latitude = geoCoordinate.Latitude * Math.PI / 180;
var longitude = geoCoordinate.Longitude * Math.PI / 180;
x += Math.Cos(latitude) * Math.Cos(longitude);
y += Math.Cos(latitude) * Math.Sin(longitude);
z += Math.Sin(latitude);
}
var total = geoCoordinates.Count;
x = x / total;
y = y / total;
z = z / total;
var centralLongitude = Math.Atan2(y, x);
var centralSquareRoot = Math.Sqrt(x * x + y * y);
var centralLatitude = Math.Atan2(z, centralSquareRoot);
return new GeoCoordinate(centralLatitude * 180 / Math.PI, centralLongitude * 180 / Math.PI);
}
Javascript 代码:
var arrLonLat = [
{'Lon' : 72.5000, 'Lat' : 22.9833},
{'Lon' : 72.8258, 'Lat' : 18.9750},
{'Lon' : 73.2003, 'Lat' : 22.3000},
{'Lon' : 75.8235, 'Lat' : 26.9260},
{'Lon' : 77.2300, 'Lat' : 28.6100},
{'Lon' : 70.7833, 'Lat' : 22.3000}];
var centerLonLat = getCenterLonLat(arrLonLat);
var lonLatSarkhej = new OpenLayers.LonLat(arrLonLat[0].Lon,arrLonLat[0].Lat).transform(epsg4326,projectTo);
var lonLatMumbai = new OpenLayers.LonLat(arrLonLat[1].Lon,arrLonLat[1].Lat).transform(epsg4326,projectTo);
var lonLatVadodara = new OpenLayers.LonLat(arrLonLat[2].Lon,arrLonLat[2].Lat).transform(epsg4326,projectTo);
var lonLatJaipur = new OpenLayers.LonLat(arrLonLat[3].Lon,arrLonLat[3].Lat).transform(epsg4326,projectTo);
var lonLatDelhi = new OpenLayers.LonLat(arrLonLat[4].Lon,arrLonLat[4].Lat).transform(epsg4326,projectTo);
var lonLatRajkot = new OpenLayers.LonLat(arrLonLat[5].Lon,arrLonLat[5].Lat).transform(epsg4326,projectTo);
//Center Point of Average Markers
var lonLatCenter = new OpenLayers.LonLat(73.681549202080149,23.696708071960074).transform(epsg4326,projectTo);
var markers = new OpenLayers.Layer.Markers("Markers");
map.addLayer(markers);
var size = new OpenLayers.Size(24,24);
var offset = new OpenLayers.Pixel(-(size.w/2), -size.h);
var icon = new OpenLayers.Icon('icon/Marker-Pink.png', size, offset);
var iconCenter = new OpenLayers.Icon('icon/Marker-Green.png', size, offset);
markers.addMarker(new OpenLayers.Marker(lonLatSarkhej,icon)); //Sarkhej
markers.addMarker(new OpenLayers.Marker(lonLatMumbai,icon.clone())); //Mumbai
markers.addMarker(new OpenLayers.Marker(lonLatVadodara,icon.clone())); //Vadodara
markers.addMarker(new OpenLayers.Marker(lonLatJaipur,icon.clone())); //Jaipur
markers.addMarker(new OpenLayers.Marker(lonLatDelhi,icon.clone())); //Delhi
markers.addMarker(new OpenLayers.Marker(lonLatRajkot,icon.clone())); //Rajkot
我正在使用粉色标记渲染6个不同的位置,并使用绿色标记作为中心。
请查看下面的图片以获得更多的解释。
现在,我已经画了一个框来了解中心标记(绿色)的位置,但它实际上并不是中心。我认为它应该位于被绿色水平和垂直线穿过的绿点上。
- 有人能告诉我,我的中心点是否计算正确吗?
- 为什么它没有显示在框的中心位置?
我还添加了标尺来计算中心点。
请帮助我找到实际的解决方案,如果需要更多细节,请告诉我。