Package cds.healpix
Interface Projection
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- All Known Implementing Classes:
Healpix
public interface Projection
Define a projection of spherical coordinates (in the unit sphere) to the Euclidean plane, together with the reverse operation. Remark: we use arrays instead of objects because HEALPix is a low level library focused on performances. Accessing an element in an array is faster than accessing a class attribute.- Author:
- F.-X. Pineau
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Field Summary
Fields Modifier and Type Field Description static int
LAT_INDEX
Index of the lattitude in the array containing the result of an unproject method.static int
LON_INDEX
Index of the longitude in the array containing the result of an unproject method.static int
X_INDEX
Index of the x coordinate in the array containing the result of a project method.static int
Y_INDEX
Index of the y coordinate in the array containing the result of a project method.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description double[]
project(double lonRad, double latRad)
Project the given spherical coordinates into the Euclidean plane.void
project(double lonRad, double latRad, double[] resultXY)
Seeproject(double, double)
with the result stored in the given array.double[]
unproject(double x, double y)
Reverse projection: we look for spherical coordinates from their projected coordinates (project(double, double)
.void
unproject(double x, double y, double[] resultLonLat)
Seeunproject(double, double)
with the result stored in the given array.
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Field Detail
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LON_INDEX
static final int LON_INDEX
Index of the longitude in the array containing the result of an unproject method.- See Also:
- Constant Field Values
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LAT_INDEX
static final int LAT_INDEX
Index of the lattitude in the array containing the result of an unproject method.- See Also:
- Constant Field Values
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X_INDEX
static final int X_INDEX
Index of the x coordinate in the array containing the result of a project method.- See Also:
- Constant Field Values
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Y_INDEX
static final int Y_INDEX
Index of the y coordinate in the array containing the result of a project method.- See Also:
- Constant Field Values
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Method Detail
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project
double[] project(double lonRad, double latRad)
Project the given spherical coordinates into the Euclidean plane.- Parameters:
lonRad
- longitude in radians (the accepted value range is implementation dependent)latRad
- latitude in [-pi/2, pi/2] radians- Returns:
- the projection of the given spherical coordinate into the Euclidean plane.
The x and y coordinate are stored in the returned array at indices
X_INDEX
andY_INDEX
respectively. The range of possible value for x and y is implementation dependent.
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project
void project(double lonRad, double latRad, double[] resultXY)
Seeproject(double, double)
with the result stored in the given array.- Parameters:
lonRad
- seeproject(double, double)
latRad
- seeproject(double, double)
resultXY
- array used to store the result. Must be of size >= 2.
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unproject
double[] unproject(double x, double y)
Reverse projection: we look for spherical coordinates from their projected coordinates (project(double, double)
.- Parameters:
x
- the x coordinate of the projected spherical point we are looking for, the accepted value range is implementation dependenty
- the y coordinate of the projected spherical point we are looking for, must be in [-2, 2].- Returns:
- the spherical coordinates leading to the given projection coordinates.
The lon and lat coordinate are stored in the returned array at indices
LON_INDEX
andLAT_INDEX
respectively. Lat is in [-pi/2, pi/2] radians, lon is also in radians but it possible value range is implementation dependent).
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unproject
void unproject(double x, double y, double[] resultLonLat)
Seeunproject(double, double)
with the result stored in the given array.- Parameters:
x
-unproject(double, double)
y
-unproject(double, double)
resultLonLat
- array used to store the result. Must be of size >= 2.
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