Package org.geotools.referencing

Class GeodeticCalculator

  • public class GeodeticCalculator
extends Object
    Performs geodetic calculations on an ellipsoid. This class encapsulates a generic ellipsoid and calculates the following properties:

    • Distance and azimuth between two points.
    • Point located at a given distance and azimuth from an other point.

    The calculation uses the following information:

    • The starting position, which is always considered valid. It is initially set at (0,0) and can only be changed to another legitimate value.
    • Only one of the following: The last one set overrides the other and determines what will be calculated.

    Note: This class is not thread-safe. If geodetic calculations are needed in a multi-threads environment, create one distinct instance of GeodeticCalculator for each thread.

    Since:
    2.1
    Author:
    Daniele Franzoni, Martin Desruisseaux

    • Constructor Detail

      • GeodeticCalculator

        public GeodeticCalculator()
        Constructs a new geodetic calculator associated with the WGS84 ellipsoid.

      • GeodeticCalculator

        public GeodeticCalculator​(Ellipsoid ellipsoid)
        Constructs a new geodetic calculator associated with the specified ellipsoid. All calculations done by the new instance are referenced to this ellipsoid.
        Parameters:
        ellipsoid - The ellipsoid onto which calculates distances and azimuths.

      • GeodeticCalculator

        public GeodeticCalculator​(CoordinateReferenceSystem crs)
        Constructs a new geodetic calculator expecting coordinates in the supplied CRS. The ellipsoid will be inferred from the CRS.
        Parameters:
        crs - The reference system for the Position objects.
        Since:
        2.2

    • Method Detail

      • getGeographicCRS

        public GeographicCRS getGeographicCRS()
        Returns the geographic coordinate reference system for all methods working on Point2D objects. This is inferred from the CRS specified at construction time.
        Returns:
        The CRS for Point2Ds.
        Since:
        2.3

      • getEllipsoid

        public Ellipsoid getEllipsoid()
        Returns the referenced ellipsoid.
        Returns:
        The referenced ellipsoid.

      • setStartingGeographicPoint

        public void setStartingGeographicPoint​(double longitude,
                                       double latitude)
                                throws IllegalArgumentException
        Set the starting point in geographic coordinates. The azimuth, the orthodromic distance and the destination point are discarted. They will need to be specified again.
        Parameters:
        longitude - The longitude in decimal degrees between -180 and +180°
        latitude - The latitude in decimal degrees between -90 and +90°
        Throws:
        IllegalArgumentException - if the longitude or the latitude is out of bounds.
        Since:
        2.3

      • setStartingGeographicPoint

        public void setStartingGeographicPoint​(Point2D point)
                                throws IllegalArgumentException
        Set the starting point in geographic coordinates. The x and y coordinates must be the longitude and latitude in decimal degrees, respectively.

        This is a convenience method for setStartingGeographicPoint(x,y).

        Parameters:
        point - The starting point.
        Throws:
        IllegalArgumentException - if the longitude or the latitude is out of bounds.
        Since:
        2.3

      • setStartingPosition

        public void setStartingPosition​(Position position)
                         throws TransformException
        Set the starting position in user coordinates, which doesn't need to be geographic. The coordinate reference system is the one specified to the constructor.
        Parameters:
        position - The position in user coordinate reference system.
        Throws:
        TransformException - if the position can't be transformed.
        Since:
        2.3

      • getStartingGeographicPoint

        public Point2D getStartingGeographicPoint()
        Returns the starting point in geographic coordinates. The x and y coordinates are the longitude and latitude in decimal degrees, respectively. If the starting point has never been set, then the default value is (0,0).
        Returns:
        The starting point in geographic coordinates.
        Since:
        2.3

      • getStartingPosition

        public Position getStartingPosition()
                             throws TransformException
        Returns the starting position in user coordinates, which doesn't need to be geographic. The coordinate reference system is the one specified to the constructor.
        Returns:
        The starting position in user CRS.
        Throws:
        TransformException - if the position can't be transformed to user coordinates.
        Since:
        2.3

      • setDestinationGeographicPoint

        public void setDestinationGeographicPoint​(double longitude,
                                          double latitude)
                                   throws IllegalArgumentException
        Set the destination point in geographic coordinates. The azimuth and distance values will be updated as a side effect of this call. They will be recomputed the next time getAzimuth() or getOrthodromicDistance() are invoked.
        Parameters:
        longitude - The longitude in decimal degrees
        latitude - The latitude in decimal degrees between -90 and +90°
        Throws:
        IllegalArgumentException - if the longitude or the latitude is out of bounds.
        Since:
        2.3

      • setDestinationGeographicPoint

        public void setDestinationGeographicPoint​(Point2D point)
                                   throws IllegalArgumentException
        Set the destination point in geographic coordinates. The x and y coordinates must be the longitude and latitude in decimal degrees, respectively.

        This is a convenience method for setDestinationGeographicPoint(x,y).

        Parameters:
        point - The destination point.
        Throws:
        IllegalArgumentException - if the longitude or the latitude is out of bounds.
        Since:
        2.3

      • setDestinationPosition

        public void setDestinationPosition​(Position position)
                            throws TransformException
        Set the destination position in user coordinates, which doesn't need to be geographic. The coordinate reference system is the one specified to the constructor.
        Parameters:
        position - The position in user coordinate reference system.
        Throws:
        TransformException - if the position can't be transformed.
        Since:
        2.2

      • getDestinationGeographicPoint

        public Point2D getDestinationGeographicPoint()
                                      throws IllegalStateException
        Returns the destination point. This method returns the point set by the last call to a setDestinationGeographicPoint(...) method, except if setDirection(...) has been invoked after. In this later case, the destination point will be computed from the starting point to the azimuth and distance specified.
        Returns:
        The destination point. The x and y coordinates are the longitude and latitude in decimal degrees, respectively.
        Throws:
        IllegalStateException - if the azimuth and the distance have not been set.
        Since:
        2.3

      • getDestinationPosition

        public Position getDestinationPosition()
                                throws TransformException
        Returns the destination position in user coordinates, which doesn't need to be geographic. The coordinate reference system is the one specified to the constructor.
        Returns:
        The destination position in user CRS.
        Throws:
        TransformException - if the position can't be transformed to user coordinates.
        Since:
        2.2

      • setDirection

        public void setDirection​(double azimuth,
                         double distance)
                  throws IllegalArgumentException
        Set the azimuth and the distance from the starting point. The destination point will be updated as a side effect of this call. It will be recomputed the next time getDestinationGeographicPoint() is invoked.
        Parameters:
        azimuth - The azimuth in decimal degrees
        distance - The orthodromic distance in the same units as the ellipsoid axis (meters by default)
        Throws:
        IllegalArgumentException - if the azimuth or the distance is out of bounds.
        See Also:
        getAzimuth(), getOrthodromicDistance()

      • getAzimuth

        public double getAzimuth()
                  throws IllegalStateException
        Returns the azimuth. This method returns the value set by the last call to setDirection(azimuth,distance), except if setDestinationGeographicPoint(...) has been invoked after. In this later case, the azimuth will be computed from the starting point to the destination point.
        Returns:
        The azimuth, in decimal degrees from -180° to +180°.
        Throws:
        IllegalStateException - if the destination point has not been set.

      • getOrthodromicDistance

        public double getOrthodromicDistance()
                              throws IllegalStateException
        Returns the orthodromic distance (expressed in meters). This method returns the value set by the last call to setDirection(azimuth,distance), except if setDestinationGeographicPoint(...) has been invoked after. In this later case, the distance will be computed from the starting point to the destination point.
        Returns:
        The orthodromic distance, in the same units as the ellipsoid axis.
        Throws:
        IllegalStateException - if the destination point has not been set.

      • getMeridianArcLength

        public double getMeridianArcLength​(double latitude1,
                                   double latitude2)
        Calculates the meridian arc length between two points in the same meridian in the referenced ellipsoid.
        Parameters:
        latitude1 - The latitude of the first point (in decimal degrees).
        latitude2 - The latitude of the second point (in decimal degrees).
        Returns:
        Returned the meridian arc length between latitude1 and latitude2

      • getGeodeticCurve

        public Shape getGeodeticCurve​(int numberOfPoints)
        Calculates the geodetic curve between two points in the referenced ellipsoid. A curve in the ellipsoid is a path which points contain the longitude and latitude of the points in the geodetic curve. The geodetic curve is computed from the starting point to the destination point.
        Parameters:
        numberOfPoints - The number of vertex in the geodetic curve. NOTE: This argument is only a hint and may be ignored in future version (if we compute a real curve rather than a list of line segments).
        Returns:
        The path that represents the geodetic curve from the starting point to the destination point.

      • getGeodeticCurve

        public Shape getGeodeticCurve()
        Calculates the geodetic curve between two points in the referenced ellipsoid. A curve in the ellipsoid is a path which points contain the longitude and latitude of the points in the geodetic curve. The geodetic curve is computed from the starting point to the destination point.
        Returns:
        The path that represents the geodetic curve from the starting point to the destination point.

      • getGeodeticPath

        public List<Point2D> getGeodeticPath​(int numPoints)
        Calculates the geodetic curve between two points in the referenced ellipsoid. A curve in the ellipsoid is a path which points contain the longitude and latitude of the points in the geodetic curve. The geodetic curve is computed from the starting point to the destination point.
        Parameters:
        numPoints - The number of vertices between the start and destination points
        Returns:
        vertices approximating the curve

      • toString

        public String toString()
        Returns a string representation of the current state of this calculator.
        Overrides:
        toString in class Object