Package com.luciad.projection

Class TLcdGeneralPerspective

java.lang.Object
com.luciad.projection.ALcdProjection
com.luciad.projection.ALcdGeneralPerspective
com.luciad.projection.TLcdGeneralPerspective
All Implemented Interfaces:
ILcdGeneralPerspective, ILcdProjection, ILcdPropertyChangeSource, Serializable, Cloneable
public class TLcdGeneralPerspective extends ALcdGeneralPerspective
General perspective projection.

Introduction Link icon

The general perspective projection is an azimuthal projection using the origin of projection and the point of perspective. The origin height is taken into account. It is possible to tilt the projection plane.

Properties Link icon

  • The central meridian and a particular parallel (if shown) are projected as straight lines.
  • Other meridians and parallels are usually arcs of circles or ellipses, but some may be parabolas or hyperbolas.
  • Neither conformal (unless Stereographic), nor equal-area.
  • If the point of perspective is above the center of the sphere or ellipsoid, les than one hemisphere may be shown (unless Orthographic).
  • If the point of perspective is below the center of the globe, more than one hemisphere may be shown (cfr. Stereographic).
  • There is considarable distortion near the projection limit.

Example Link icon

Sample code Link icon


 ILcdProjection projection =
     new TLcdGeneralPerspective(40.0, -100.0, 0.0, 2.0, 0.0, 0.0);

Implementation aspects Link icon

The equations of the general perspective projection are taken from [Snyder1987].

Note Link icon

The point of perspective has to be outside the earth ellipsoid. So, its value should be outside the closed interval [-1.0,1.0].

See Also:

  • Constructor Details Link icon

    • TLcdGeneralPerspective Link icon

      public TLcdGeneralPerspective()
      Constructs a general perspective projection with the origin at point (0.0, 0.0, 0.0), the perspective distance at 2.0, the azimuth set to 0.0, and the tilt set to 0.0.

    • TLcdGeneralPerspective Link icon

      public TLcdGeneralPerspective(double aLongitude, double aLatitude, double aHeight, double aPerspectiveDistance, double aAzimuth, double aTiltAngle)
      Constructs a general perspective projection with the origin at a point (aLatitude, aLongitude, aHeight).
      Parameters:
      aLongitude - longitude of the origin of the projection, in decimal degrees.
      aLatitude - latitude of the origin of the projection, in decimal degrees.
      aHeight - height of the origin point above the ellipsoid.
      aPerspectiveDistance - distance of the point of perspective from the center of the earth globe divided by the semi-major axis.
      aAzimuth - azimuth east of north of the Y-axis of the Y_t axis of the tilted plane of projection
      aTiltAngle - upward angle of tilt, or the angle between the Y_t axis and the tangent plane, expressed in degrees

    • TLcdGeneralPerspective Link icon

      public TLcdGeneralPerspective(ILcdPoint aOrigin, double aPerspectiveDistance)
      Constructs a general perspective projection with the origin at an ILcdPoint aOrigin and a point of perspective at a distance (divided by the semi-major axis) from the center of the earth. The properties azimuth and tiltAngle are set to zero.
      Parameters:
      aOrigin - point of origin (3D) of the projection.
      aPerspectiveDistance - distance of the point of perspective from the center of the earth globe divided by the semi-major axis.

    • TLcdGeneralPerspective Link icon

      public TLcdGeneralPerspective(ILcdPoint aOrigin, double aPerspectiveDistance, double aAzimuth, double aTiltAngle)
      Constructs a general perspective projection with the origin at an ILcdPoint aOrigin and a point of perspective at a distance (divided by the semi-major axis) from the center of the earth.
      Parameters:
      aOrigin - point of origin (3D) of the projection.
      aPerspectiveDistance - distance of the point of perspective from the center of the earth globe divided by the semi-major axis.
      aAzimuth - azimuth east of north of the Y-axis of the Y_t axis of the tilted plane of projection
      aTiltAngle - upward angle of tilt, or the angle between the Y_t axis and the tangent plane, expressed in degrees

  • Method Details Link icon

    • calculateCachedValues Link icon

      protected void calculateCachedValues()
      Description copied from class: ALcdGeneralPerspective
      Constants based on the longitude, latitude, height of the point of origin of projection and the distance of the point of perspective 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 precalculated values then can be used in order to gain efficiency.
      Overrides:
      calculateCachedValues in class ALcdGeneralPerspective

    • isAllInBounds Link icon

      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 Link icon

      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.

    • lonlatheight2worldOnEllipsoidSFCT Link icon

      public void lonlatheight2worldOnEllipsoidSFCT(ILcdPoint aLLHP, ILcdEllipsoid aEllipsoid, ILcd2DEditablePoint aWorldPoint) throws TLcdOutOfBoundsException
      Description copied from class: ALcdProjection
      Default implementation calls lonlatheight2worldOnEllipsoidSFCT with aEllipsoid.getAuxRadius() as sphere radius.
      Specified by:
      lonlatheight2worldOnEllipsoidSFCT in interface ILcdProjection
      Overrides:
      lonlatheight2worldOnEllipsoidSFCT in class ALcdProjection
      Parameters:
      aLLHP - point to be projected.
      aEllipsoid - ellipsoid on which the point is defined.
      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 Link icon

      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.

    • world2lonlatOnEllipsoidSFCT Link icon

      public void world2lonlatOnEllipsoidSFCT(ILcdPoint aXYPoint, ILcdEllipsoid aEllipsoid, ILcd2DEditablePoint aLLPSFCT) throws TLcdOutOfBoundsException
      Transforms a world point to a LonLatHeightPoint. The height, which is taken into account, is supposed to be available in the input/output parameter aLLPSFCT.
      Specified by:
      world2lonlatOnEllipsoidSFCT in interface ILcdProjection
      Overrides:
      world2lonlatOnEllipsoidSFCT in class ALcdProjection
      Parameters:
      aXYPoint - projected point for which the corresponding geodetic point is sought.
      aEllipsoid - ellipsoid on which the geodetic coordinate is defined.
      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 Link icon

      public boolean inLonLatBounds(ILcdPoint aLLP)
      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:
      aLLP - ILcdPoint to be checked upon.
      Returns:
      true if valid, false if invalid.

    • boundaryLons Link icon

      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 Link icon

      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 Link icon

      public void world2DEditableBoundsOnSphereSFCT(double aRadius, ILcd2DEditableBounds aWorldBound)
      The projection is bounded when the perspective distance is outside the closed interval [-1,1]. Currently a perspective distance within this closed interval [-1,1] is not supported.
      Parameters:
      aRadius - radius of the sphere.
      aWorldBound - the bounds of the projection in world coordinates as side effect.

    • inWorldBoundsOnSphere Link icon

      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 Link icon

      public String toString()
      Returns the String representation of the general perspective projection.
      Specified by:
      toString in interface ILcdProjection
      Overrides:
      toString in class Object
      Returns:
      the String representation of the general perspective projection.

    • clone Link icon

      public Object clone()
      Description copied from interface: ILcdProjection
      Makes a deep clone of this ILcdProjection.
      Specified by:
      clone in interface ILcdProjection
      Overrides:
      clone in class ALcdGeneralPerspective
      Returns:
      deep clone of this ILcdProjection.