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
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:
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Field Summary
Fields inherited from class com.luciad.projection.ALcdProjection
fPropertyChangeDispatcher
Fields inherited from interface com.luciad.projection.ILcdProjection
EPSILON
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Constructor Summary
ConstructorDescriptionConstructs a lambert azimuthal equal-area projection with the origin at a point(0.0, 0.0)
.TLcdLambertAzimuthalEqualArea
(double aLongitude, double aLatitude) Constructs a lambert azimuthal equal-area projection with the origin at a point(aLatitude, aLongitude)
.TLcdLambertAzimuthalEqualArea
(ILcdPoint aOrigin) Constructs a lambert azimuthal equal-area projection with the origin at anILcdPoint
aOrigin
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Method Summary
Modifier and TypeMethodDescriptiondouble[][]
boundaryLats
(double lon) Default implementation.double[][]
boundaryLons
(double lat) Default implementation.protected void
Constants based on the point of origin of the projection don't have to be recalculated every time a method is called.boolean
inLonLatBounds
(ILcdPoint aLLHP) Checks if anILcdPoint
is inside the valid area of geodetic coordinates of the projection.boolean
inWorldBoundsOnSphere
(ILcdPoint aXYPoint, double aRadius) Checks if aILcdPoint
is inside the valid cartesian area of the projection.boolean
If all geodetic coordinates (l ,j ) are projected (visible) by anILcdProjection
and all (x,y ) coordinates are bounded this istrue
.void
lonlatheight2worldOnSphereSFCT
(ILcdPoint aLLHP, double aRadius, ILcd2DEditablePoint aWorldPoint) Transforms anILcd2DEditablePoint
on a sphere into the cartesian coordinate system of the projection.toString()
Returns theString
representation of the lambert azimuthal equal-area projection.void
world2DEditableBoundsOnSphereSFCT
(double aRadius, ILcd2DEditableBounds aWorldBound) The whole earth globe is projected except the point opposite the origin.void
world2lonlatOnSphereSFCT
(ILcdPoint aXYPoint, double aRadius, ILcd2DEditablePoint aLLPSFCT) Transforms anILcdPoint
from the cartesian coordinate system of the projection into anILcd2DEditablePoint
onto a sphere.Methods inherited from class com.luciad.projection.ALcdAzimuthal
clone, equals, getOrigin, getOriginLat, getOriginLon, hashCode, isContinuous, loadProperties, setOriginLat, setOriginLon, writePropertiesSFCT
Methods inherited from class com.luciad.projection.ALcdProjection
addPropertyChangeListener, firePropertyChangeEvent, inWorldBoundsOnEllipsoid, lonlatheight2worldOnEllipsoidSFCT, removePropertyChangeListener, world2DEditableBoundsOnEllipsoidSFCT, world2lonlatOnEllipsoidSFCT
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface com.luciad.projection.ILcdProjection
inWorldBoundsOnEllipsoid, lonlatheight2worldOnEllipsoidSFCT, world2DEditableBoundsOnEllipsoidSFCT, world2lonlatOnEllipsoidSFCT
Methods inherited from interface com.luciad.util.ILcdPropertyChangeSource
addPropertyChangeListener, removePropertyChangeListener
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Constructor Details
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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 longitudeaLongitude
.- Parameters:
aLongitude
- longitude of the origin of the projection, in decimal degrees.aLatitude
- latitude of the origin of the projection, in decimal degrees.
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TLcdLambertAzimuthalEqualArea
Constructs a lambert azimuthal equal-area projection with the origin at anILcdPoint
aOrigin
. The central meridian is ataOrigin.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 toaOrigin
.
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Method Details
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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 classALcdAzimuthal
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isAllInBounds
public boolean isAllInBounds()Description copied from interface:ILcdProjection
If all geodetic coordinates (l ,j ) are projected (visible) by anILcdProjection
and all (x,y ) coordinates are bounded this istrue
. AllILcdProjection
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.
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lonlatheight2worldOnSphereSFCT
public void lonlatheight2worldOnSphereSFCT(ILcdPoint aLLHP, double aRadius, ILcd2DEditablePoint aWorldPoint) throws TLcdOutOfBoundsException Description copied from interface:ILcdProjection
Transforms anILcd2DEditablePoint
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 theILcdPoint
aLLHP
is not within the valid area of the projection (visible area), then this exception is thrown.
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world2lonlatOnSphereSFCT
public void world2lonlatOnSphereSFCT(ILcdPoint aXYPoint, double aRadius, ILcd2DEditablePoint aLLPSFCT) throws TLcdOutOfBoundsException Description copied from interface:ILcdProjection
Transforms anILcdPoint
from the cartesian coordinate system of the projection into anILcd2DEditablePoint
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 theILcdPoint
aXYPoint
is not within the valid area of the projection (visible area), then this exception is thrown.
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inLonLatBounds
Description copied from interface:ILcdProjection
Checks if anILcdPoint
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.
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boundaryLons
public double[][] boundaryLons(double lat) Description copied from class:ALcdProjection
Default implementation. To be redefined for specific projections.- Specified by:
boundaryLons
in interfaceILcdProjection
- Overrides:
boundaryLons
in classALcdProjection
- 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.
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boundaryLats
public double[][] boundaryLats(double lon) Description copied from class:ALcdProjection
Default implementation. To be redefined for specific projections.- Specified by:
boundaryLats
in interfaceILcdProjection
- Overrides:
boundaryLats
in classALcdProjection
- 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 .
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world2DEditableBoundsOnSphereSFCT
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.
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inWorldBoundsOnSphere
Description copied from interface:ILcdProjection
Checks if aILcdPoint
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.
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toString
Returns theString
representation of the lambert azimuthal equal-area projection.- Specified by:
toString
in interfaceILcdProjection
- Overrides:
toString
in classObject
- Returns:
- the
String
representation of the lambert azimuthal equal-area projection.
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