常用坐标系介紹
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WGS-84(GPS)
國際标準,一般從國際标準的GPS裝置擷取的坐标都是WGS-84,以及國際地圖提供商使用的坐标系。
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GCJ-02
中國标準,國測局02年釋出的坐标系。又稱“火星坐标”。在中國,必須至少使用“GCJ-02”對地理位置進行首次加密。比如谷歌中國、高德、騰訊都在用這個坐标系。
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BD-09
百度标準,在“GCJ-02”的基礎上進行二次加密。
北鬥定位系統坐标
如果有對接過北鬥定位系統的小夥伴可能會發現一個問題,北鬥坐标經緯度好像都被乘了100?
$GNRMC,083735.000,A,2429.53531,N,11810.78036,E,0.54,171.11,190621,A*7E
這個,就是我們北鬥定位系統接收到的坐标值,可以發現,北緯是2429.53531,東經是11810.78036,倘若我們直接将這個經緯度除100,北緯24.2953531,東經118.1078036,扔到百度或者高德地圖中,我們會發現,坐标偏移的離譜。
高德地圖定位:
百度地圖定位:
可以發現,兩者的距離都偏移了幾十公裡,這個原因就在于,國内,無論是高德還是百度,它們所使用的經緯度值,都是經過加密之後的值,而不是直接用GPS的實際經緯度來定位的,是以,我們如果想要将北鬥定位系統的坐标系,用于商業地圖上,則需要将它經過對應的加密轉換處理才能夠正确的使用。
坐标系的互相轉換
首先,要強調一點,其實我們北鬥定位的坐标系值并不是簡單的100倍關系,而是需要做一次度分秒的轉換的。則我們擷取的北鬥坐标值,北緯2429.53531,東經11810.78036,需要做如下計算:24+(29.53531/60)≈ 24.49225517 118+(10.78036/60)≈118.17967267
這兩個值才是我們應該帶入轉換公式的坐标值,如果直接用100倍關系的值去轉換,定位一樣會偏差
接着上代碼
public static final String BAIDU_LBS_TYPE = "bd09ll";
public static double pi = 3.1415926535897932384626;
public static double a = 6378245.0;
public static double ee = 0.00669342162296594323;
/**
* 北鬥坐标系度分秒計算
* @param msg
* @return
*/
public static GPS str_To_Gps84(String msg){
double lat = 0;
double lon = 0;
String[] split = msg.split(",");
if (split[4].equals("N") || split[4].equals("S")){
int i = split[3].indexOf(".");
String latInt = split[3].substring(0, i - 2);
String latDec = split[3].substring(i-2);
int i1 = split[5].indexOf(".");
String lonInt = split[5].substring(0, i1-2);
String lonDec = split[5].substring(i1-2);
lat = Integer.parseInt(latInt) + Double.parseDouble(latDec)/60;
lon = Integer.parseInt(lonInt) + Double.parseDouble(lonDec)/60;
System.out.println("latInt = "+ latInt);
System.out.println("latDec = "+ latDec);
System.out.println("lonInt = "+ lonInt);
System.out.println("lonDec = "+ lonDec);
System.out.println("lat = "+ lat);
System.out.println("lon = "+ lon);
} else {
return null;
}
return new GPS(lat,lon);
}
/**
* 84 to 火星坐标系 (GCJ-02)
* @param lat
* @param lon
*/
public static GPS gps84_To_Gcj02(double lat, double lon) {
if (outOfChina(lat, lon))
{
return null;
}
double dLat = transformLat(lon - 105.0, lat - 35.0);
double dLon = transformLon(lon - 105.0, lat - 35.0);
double radLat = lat / 180.0 * pi;
double magic = Math.sin(radLat);
magic = 1 - ee * magic * magic;
double sqrtMagic = Math.sqrt(magic);
dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
double mgLat = lat + dLat;
double mgLon = lon + dLon;
return new GPS(mgLat, mgLon);
}
/**
* * 火星坐标系 (GCJ-02) to 84
* * @param lon * @param lat * @return
*/
public static GPS gcj_To_Gps84(double lat, double lon) {
GPS gps = transform(lat, lon);
double lontitude = lon * 2 - gps.getLon();
double latitude = lat * 2 - gps.getLat();
return new GPS(latitude, lontitude);
}
/**
* 将 GCJ-02 坐标轉換成 BD-09 坐标
*
* @param gg_lat
* @param gg_lon
*/
public static GPS gcj02_To_Bd09(double gg_lat, double gg_lon) {
double x = gg_lon, y = gg_lat;
double z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * pi);
double theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * pi);
double bd_lon = z * Math.cos(theta) + 0.0065;
double bd_lat = z * Math.sin(theta) + 0.006;
return new GPS(bd_lat, bd_lon);
}
/**
* * 将 BD-09 坐标轉換成GCJ-02 坐标 *
* * @param
* bd_lat * @param bd_lon * @return
*/
public static GPS bd09_To_Gcj02(double bd_lat, double bd_lon) {
double x = bd_lon - 0.0065;
double y = bd_lat - 0.006;
double z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * pi);
double theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * pi);
double gg_lon = z * Math.cos(theta);
double gg_lat = z * Math.sin(theta);
return new GPS(gg_lat, gg_lon);
}
/**
* (BD-09)-->84
* @param bd_lat
* @param bd_lon
* @return
*/
public static GPS bd09_To_Gps84(double bd_lat, double bd_lon) {
GPS gcj02 = bd09_To_Gcj02(bd_lat, bd_lon);
GPS map84 = gcj_To_Gps84(gcj02.getLat(),
gcj02.getLon());
return map84;
}
/**
* is or not outOfChina
* @param lat
* @param lon
* @return
*/
public static boolean outOfChina(double lat, double lon) {
if (lon < 72.004 || lon > 137.8347)
return true;
if (lat < 0.8293 || lat > 55.8271)
return true;
return false;
}
public static GPS transform(double lat, double lon) {
if (outOfChina(lat, lon)) {
return new GPS(lat, lon);
}
double dLat = transformLat(lon - 105.0, lat - 35.0);
double dLon = transformLon(lon - 105.0, lat - 35.0);
double radLat = lat / 180.0 * pi;
double magic = Math.sin(radLat);
magic = 1 - ee * magic * magic;
double sqrtMagic = Math.sqrt(magic);
dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
double mgLat = lat + dLat;
double mgLon = lon + dLon;
return new GPS(mgLat, mgLon);
}
public static double transformLat(double x, double y) {
double ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y
+ 0.2 * Math.sqrt(Math.abs(x));
ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
ret += (20.0 * Math.sin(y * pi) + 40.0 * Math.sin(y / 3.0 * pi)) * 2.0 / 3.0;
ret += (160.0 * Math.sin(y / 12.0 * pi) + 320 * Math.sin(y * pi / 30.0)) * 2.0 / 3.0;
return ret;
}
public static double transformLon(double x, double y) {
double ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1
* Math.sqrt(Math.abs(x));
ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
ret += (20.0 * Math.sin(x * pi) + 40.0 * Math.sin(x / 3.0 * pi)) * 2.0 / 3.0;
ret += (150.0 * Math.sin(x / 12.0 * pi) + 300.0 * Math.sin(x / 30.0
* pi)) * 2.0 / 3.0;
return ret;
}
//求兩坐标距離
public static double distance(double lonA,double latA,double lonB,double latB){
int earthR = 6371000;
double x = Math.cos(latA * PI / 180.) * Math.cos(latB * PI / 180.) * Math.cos((lonA - lonB) * PI / 180);
double y = Math.sin(latA * PI / 180.) * Math.sin(latB * PI / 180.);
double s = x + y;
if (s > 1) s = 1;
if (s < -1) s = -1;
double alpha = Math.acos(s);
double distance = alpha * earthR;
return distance;
}
//重載,根據兩個點求距離
public static double distance(GPS p1,GPS p2){
return distance(p1.getLon(), p1.getLat(), p2.getLon(), p2.getLat());
}
高德地圖用的GCJ-02坐标系轉換結果:
public CommonResult test() {
String msg = "$GNRMC,083735.000,A,2429.53531,N,11810.78036,E,0.54,171.11,190621,,,A*7E";
GPS gps2 = GPSConverterUtils.str_To_Gps84(msg);
GPS gps = GPSConverterUtils.gps84_To_Gcj02(gps2.getLat(), gps2.getLon());
return CommonResult.success(gps);
}
"lat": 24.489503175446604, "lon": 118.18449589009587
可以看到轉換過來後的坐标系,精确定位到了我們辦公樓
百度坐标系的BD-09坐标系轉換結果:
public CommonResult test() {
String msg = "$GNRMC,083735.000,A,2429.53531,N,11810.78036,E,0.54,171.11,190621,,,A*7E";
GPS gps2 = GPSConverterUtils.str_To_Gps84(msg);
GPS gps = GPSConverterUtils.gps84_To_Gcj02(gps2.getLat(), gps2.getLon());
GPS gps1 = GPSConverterUtils.gcj02_To_Bd09(gps.getLat(), gps.getLon());
return CommonResult.success(gps1);
}
"lat": 24.49580387761381, "lon": 118.19095399371493
可以看到百度地圖也精确的定位到了我們的辦公樓
結論
谷歌地圖那些,用的是WGS-84坐标系,北鬥定位系統給到的坐标值要做一次度分秒的轉換,轉換後才是84坐标,像高德地圖那些用的是GCJ-02火星坐标系,等于要先做一次GCJ-02加密,坐标系才能在高德地圖用,百度地圖則需要再做一次BD-09的加密