Calculate distance in meters when you know longitude and latitude in java

Possible Duplicate:
Working with latitude/longitude values in Java

Duplicate:

Working with latitude/longitude values in Java

How do I calculate distance between two latitude longitude points?

I need to calculate the distance between two points given by two coordinates. The project I am working on is a Java-project, so Java-code will be great, but pseudo-code can also be given, then I can implement it myself :)

As you probably know, there are three ways to represent coordinates:

Degrees:Minutes:Seconds (49°30'00"N, 123°30'00"W)

Degrees:Decimal Minutes (49°30.0', -123°30.0'), (49d30.0m,-123d30.0')

Decimal Degrees (49.5000°,-123.5000°), generally with 4-6 decimal numbers.

It's the third way my coordinates are given in, so the code for this values will be preferred :)

---

基于stackoverflow上的另一个问题，我得到了这个代码..这以米为单位计算结果，而不是英里:)

 public static float distFrom(float lat1, float lng1, float lat2, float lng2) {
    double earthRadius = 6371000; //meters
    double dLat = Math.toRadians(lat2-lat1);
    double dLng = Math.toRadians(lng2-lng1);
    double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
               Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) *
               Math.sin(dLng/2) * Math.sin(dLng/2);
    double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
    float dist = (float) (earthRadius * c);

    return dist;
    }

---

You can use the Java Geodesy Library for GPS, it uses the Vincenty's formulae which takes account of the earths surface curvature.

Implementation goes like this:

import org.gavaghan.geodesy.*;

...

GeodeticCalculator geoCalc = new GeodeticCalculator();

Ellipsoid reference = Ellipsoid.WGS84;  

GlobalPosition pointA = new GlobalPosition(latitude, longitude, 0.0); // Point A

GlobalPosition userPos = new GlobalPosition(userLat, userLon, 0.0); // Point B

double distance = geoCalc.calculateGeodeticCurve(reference, userPos, pointA).getEllipsoidalDistance(); // Distance between Point A and Point B

The resulting distance is in meters.

---

在C ++中，它是这样做的：

#define LOCAL_PI 3.1415926535897932385 

double ToRadians(double degrees) 
{
  double radians = degrees * LOCAL_PI / 180;
  return radians;
}

double DirectDistance(double lat1, double lng1, double lat2, double lng2) 
{
  double earthRadius = 3958.75;
  double dLat = ToRadians(lat2-lat1);
  double dLng = ToRadians(lng2-lng1);
  double a = sin(dLat/2) * sin(dLat/2) + 
             cos(ToRadians(lat1)) * cos(ToRadians(lat2)) * 
             sin(dLng/2) * sin(dLng/2);
  double c = 2 * atan2(sqrt(a), sqrt(1-a));
  double dist = earthRadius * c;
  double meterConversion = 1609.00;
  return dist * meterConversion;
}

链接地址: http://www.djcxy.com/p/70968.html

上一篇: 计算知道起点和距离的第二点

下一篇: 当您知道java中的经度和纬度时，以米为单位计算距离