Package com.luciad.projection

Class TLcdLambertAzimuthalEqualArea

java.lang.Object
com.luciad.projection.ALcdProjection
com.luciad.projection.ALcdAzimuthal
com.luciad.projection.TLcdLambertAzimuthalEqualArea
All Implemented Interfaces:
ILcdAzimuthal, ILcdProjection, ILcdPropertyChangeSource, Serializable, Cloneable
public class TLcdLambertAzimuthalEqualArea extends ALcdAzimuthal
Spherical Lambert Azimuthal Equal-Area projection.

Introduction

Azimuthal equal area projection with a point of origin for the projection. It accurately shows area in all regions of the ellipsoid, but it does not accurately represent angles. Intuitively, it shows a disk in which every region appears with the correct area but perhaps a greatly distorted shape.

Properties

  • Equal-area
  • All meridians in the polar aspect and the central meridian in other aspects are shown as straight lines.
  • The Equator in the equatorial aspect is shown as a straight line.
  • The outer meridian in the equatorial aspect and the parallels in the polar aspect are circles.
  • All other meridians an parallels are complex curves.
  • This projection is not a perspective projection.
  • Scale decreases radially as the distance increases from the center, the only point without distortion.
  • Scale increases in the direction perpendicular to radii as the distance increases from the center.
  • Directions from the origin of projection are true.
  • Point opposite the origin of projection is show as a circle surrounding the map.

Example

Sample code


 ILcdProjection projection =
     new TLcdLambertAzimuthalEqualArea(20.0, -40.0);

Implementation aspects

The equations of the lambert azimuthal equal-area projection are taken from [Snyder1987].

Limitations

Only the spherical form of the projection is implemented. See TLcdEllipsoidalLambertAzimuthalEqualArea for an implementation that uses ellipsoidal calculations.

See Also:

  • Constructor Details

    • TLcdLambertAzimuthalEqualArea

      public TLcdLambertAzimuthalEqualArea()
      Constructs a lambert azimuthal equal-area projection with the origin at a point (0.0, 0.0).

    • TLcdLambertAzimuthalEqualArea

      public TLcdLambertAzimuthalEqualArea(double aLongitude, double aLatitude)
      Constructs a lambert azimuthal equal-area projection with the origin at a point (aLatitude, aLongitude). The central meridian is at the longitude aLongitude.
      Parameters:
      aLongitude - longitude of the origin of the projection, in decimal degrees.
      aLatitude - latitude of the origin of the projection, in decimal degrees.

    • TLcdLambertAzimuthalEqualArea

      public TLcdLambertAzimuthalEqualArea(ILcdPoint aOrigin)
      Constructs a lambert azimuthal equal-area projection with the origin at an ILcdPoint aOrigin. The central meridian is at aOrigin.getX().
      Parameters:
      aOrigin - ILcdPoint of the origin of the projection. aOrigin is cloned within the constructor, so no side effects will happen to the projection as a result from changes to aOrigin.

  • Method Details

    • calculateCachedValues

      protected void calculateCachedValues()
      Description copied from class: ALcdAzimuthal
      Constants based on the point of origin of the projection don't have to be recalculated every time a method is called. They only have to be calculated when the projection properties change. Within the methods the pre-calculated values then can be used in order to gain efficiency.
      Overrides:
      calculateCachedValues in class ALcdAzimuthal

    • isAllInBounds

      public boolean isAllInBounds()
      Description copied from interface: ILcdProjection
      If all geodetic coordinates (l ,j ) are projected (visible) by an ILcdProjection and all (x,y ) coordinates are bounded this is true. All ILcdProjection objects have bounded (x,y ) coordinates because the projection is cut off if necessary.
      Returns:
      true if all LonLatPoints are within the bounds of the projection, false otherwise.

    • lonlatheight2worldOnSphereSFCT

      public void lonlatheight2worldOnSphereSFCT(ILcdPoint aLLHP, double aRadius, ILcd2DEditablePoint aWorldPoint) throws TLcdOutOfBoundsException
      Description copied from interface: ILcdProjection
      Transforms an ILcd2DEditablePoint on a sphere into the cartesian coordinate system of the projection.
      Parameters:
      aLLHP - point to be projected.
      aRadius - radius of the sphere (meters).
      aWorldPoint - projected point as side effect.
      Throws:
      TLcdOutOfBoundsException - If the ILcdPoint aLLHP is not within the valid area of the projection (visible area), then this exception is thrown.

    • world2lonlatOnSphereSFCT

      public void world2lonlatOnSphereSFCT(ILcdPoint aXYPoint, double aRadius, ILcd2DEditablePoint aLLPSFCT) throws TLcdOutOfBoundsException
      Description copied from interface: ILcdProjection
      Transforms an ILcdPoint from the cartesian coordinate system of the projection into an ILcd2DEditablePoint onto a sphere.
      Parameters:
      aXYPoint - projected point for which the corresponding geodetic point is sought.
      aRadius - radius of the sphere (meters).
      aLLPSFCT - resulting geodetic coordinate as side effect.
      Throws:
      TLcdOutOfBoundsException - If the ILcdPoint aXYPoint is not within the valid area of the projection (visible area), then this exception is thrown.

    • inLonLatBounds

      public boolean inLonLatBounds(ILcdPoint aLLHP)
      Description copied from interface: ILcdProjection
      Checks if an ILcdPoint is inside the valid area of geodetic coordinates of the projection. The valid area is determined by the LonLatPoints that are visible and for which the corresponding cartesian coordinate is within the boundaries.
      Parameters:
      aLLHP - ILcdPoint to be checked upon.
      Returns:
      true if valid, false if invalid.

    • boundaryLons

      public double[][] boundaryLons(double lat)
      Description copied from class: ALcdProjection
      Default implementation. To be redefined for specific projections.
      Specified by:
      boundaryLons in interface ILcdProjection
      Overrides:
      boundaryLons in class ALcdProjection
      Parameters:
      lat - latitude in decimal degrees and -90.0 <= aLat<= 90.0.
      Returns:
      the array of pairs of longitudes[0] and longitudes[1], where the closed interval longitudes[0] -> longitudes[1] is in visible area and -180.0 <= lon[i] <= 180.0.

    • boundaryLats

      public double[][] boundaryLats(double lon)
      Description copied from class: ALcdProjection
      Default implementation. To be redefined for specific projections.
      Specified by:
      boundaryLats in interface ILcdProjection
      Overrides:
      boundaryLats in class ALcdProjection
      Parameters:
      lon - longitude in decimal degrees -180.0 <= lon <= 180.0 .
      Returns:
      the array of pairs of latitudes lats[0] and lats[1], where the closed interval lats[0] -> lats[1] is in visible area and -90.0 <= lats[i] <= 90.0 .

    • world2DEditableBoundsOnSphereSFCT

      public void world2DEditableBoundsOnSphereSFCT(double aRadius, ILcd2DEditableBounds aWorldBound)
      The whole earth globe is projected except the point opposite the origin.
      Parameters:
      aRadius - radius of the sphere.
      aWorldBound - the bounds of the projection in world coordinates as side effect.

    • inWorldBoundsOnSphere

      public boolean inWorldBoundsOnSphere(ILcdPoint aXYPoint, double aRadius)
      Description copied from interface: ILcdProjection
      Checks if a ILcdPoint is inside the valid cartesian area of the projection. The valid cartesian area is determined naturally by the projection bounds or by an artificial introduced boundary limit because some cartesian points are at infinity. The shape of the valid cartesian area is in many cases rectangular or circular although it might be more complex.
      Parameters:
      aXYPoint - point to be checked upon.
      aRadius - radius of the sphere.
      Returns:
      true if valid, false if invalid.

    • toString

      public String toString()
      Returns the String representation of the lambert azimuthal equal-area projection.
      Specified by:
      toString in interface ILcdProjection
      Overrides:
      toString in class Object
      Returns:
      the String representation of the lambert azimuthal equal-area projection.