public class Tilings extends Object
The k
parameter for the HEALPix functions is the
HEALPix order, which can be in the range 0<=k<=29.
This is the logarithm to base 2 of the HEALPix NSIDE parameter.
At order k
, there are 12*4^k pixels on the sphere.
Modifier and Type | Field and Description |
---|---|
static double |
SQDEG
Solid angle in steradians corresponding to 1 square degree.
|
Modifier and Type | Method and Description |
---|---|
static int |
healpixK(double pixelsize)
Gives the HEALPix resolution parameter suitable for a given pixel size.
|
static long |
healpixNestIndex(int k,
double lon,
double lat)
Gives the pixel index for a given sky position in the HEALPix
NEST scheme.
|
static double |
healpixNestLat(int k,
long index)
Returns the latitude of the approximate center of the tile
with a given index in the HEALPix NEST scheme.
|
static double |
healpixNestLon(int k,
long index)
Returns the longitude of the approximate center of the tile
with a given index in the HEALPix NEST scheme.
|
static long |
healpixNestToRing(int k,
long nestIndex)
Converts a healpix tile index from the NEST to the RING scheme
at a given order.
|
static double |
healpixResolution(int k)
Gives the approximate resolution in degrees for a given HEALPix
resolution parameter
k
This k value is the logarithm to base 2 of the
Nside parameter. |
static long |
healpixRingIndex(int k,
double lon,
double lat)
Gives the pixel index for a given sky position in the HEALPix
RING scheme.
|
static double |
healpixRingLat(int k,
long index)
Returns the latitude of the approximate center of the tile
with a given index in the HEALPix RING scheme.
|
static double |
healpixRingLon(int k,
long index)
Returns the longitude of the approximate center of the tile
with a given index in the HEALPix RING scheme.
|
static long |
healpixRingToNest(int k,
long ringIndex)
Converts a healpix tile index from the RING to the NEST scheme
at a given order.
|
static double |
healpixSqdeg(int k)
Returns the solid angle in square degrees of each HEALPix pixel
at a given order.
|
static double |
healpixSteradians(int k)
Returns the solid angle in steradians of each HEALPix pixel
at a given order.
|
static long |
htmIndex(int level,
double lon,
double lat)
Gives the HTM (Hierachical Triangular Mesh) pixel index for a given
sky position.
|
static int |
htmLevel(double pixelsize)
Gives the HTM
level parameter suitable for a given
pixel size. |
static double |
htmResolution(int level)
Gives the approximate resolution in degrees for a given HTM depth level.
|
static double |
sqdegToSteradians(double sqdeg)
Converts a solid angle from square degrees to steradians.
|
static double |
steradiansToSqdeg(double sr)
Converts a solid angle from steradians to square degrees.
|
public static final double SQDEG
public static long htmIndex(int level, double lon, double lat)
level
- HTM levellon
- longitude in degreeslat
- latitude in degreespublic static long healpixNestIndex(int k, double lon, double lat)
k
- HEALPix order (0..29)lon
- longitude in degreeslat
- latitude in degreespublic static long healpixRingIndex(int k, double lon, double lat)
k
- HEALPix order (0..29)lon
- longitude in degreeslat
- latitude in degreespublic static double healpixNestLon(int k, long index)
Note: the index
parameter is 0-based,
unlike the table row index special token $index
(a.k.a. $0
), which is 1-based.
So if the HEALpix index is implicitly determined by the table row,
the value $index-1
should be used.
k
- HEALPix order (0..29)index
- healpix indexpublic static double healpixNestLat(int k, long index)
Note: the index
parameter is 0-based,
unlike the table row index special token $index
(a.k.a. $0
), which is 1-based.
So if the HEALpix index is implicitly determined by the table row,
the value $index-1
should be used.
k
- HEALPix order (0..29)index
- healpix indexpublic static double healpixRingLon(int k, long index)
Note: the index
parameter is 0-based,
unlike the table row index special token $index
(a.k.a. $0
), which is 1-based.
So if the HEALpix index is implicitly determined by the table row,
the value $index-1
should be used.
k
- HEALPix order (0..29)index
- healpix indexpublic static double healpixRingLat(int k, long index)
Note: the index
parameter is 0-based,
unlike the table row index special token $index
(a.k.a. $0
), which is 1-based.
So if the HEALpix index is implicitly determined by the table row,
the value $index-1
should be used.
k
- HEALPix order (0..29)index
- healpix indexpublic static long healpixNestToRing(int k, long nestIndex)
Note: the nestIndex
parameter is 0-based,
unlike the table row index special token $index
(a.k.a. $0
), which is 1-based.
So if the HEALpix index is implicitly determined by the table row,
the value $index-1
should be used.
k
- HEALPix order (0..29)nestIndex
- pixel index in NEST schemepublic static long healpixRingToNest(int k, long ringIndex)
Note: the ringIndex
parameter is 0-based,
unlike the table row index special token $index
(a.k.a. $0
), which is 1-based.
So if the HEALpix index is implicitly determined by the table row,
the value $index-1
should be used.
k
- HEALPix order (0..29)ringIndex
- pixel index in RING schemepublic static int healpixK(double pixelsize)
k
value (also variously known as order, level, depth)
is the logarithm to base 2 of the
Nside parameter.pixelsize
- pixel size in degreesk
public static double healpixResolution(int k)
k
This k
value is the logarithm to base 2 of the
Nside parameter.k
- HEALPix order (0..29)public static double healpixSteradians(int k)
k
- HEALPix order (0..29)public static double healpixSqdeg(int k)
k
- HEALPix order (0..29)public static double steradiansToSqdeg(double sr)
The unit sphere is 4*PI steradians = 360*360/PI square degrees.
sr
- quantity in steradianspublic static double sqdegToSteradians(double sqdeg)
The unit sphere is 4*PI steradians = 360*360/PI square degrees.
sqdeg
- quantity in square degreespublic static int htmLevel(double pixelsize)
level
parameter suitable for a given
pixel size.pixelsize
- required resolution in degreespublic static double htmResolution(int level)
level
- HTM depthCopyright © 2024 Central Laboratory of the Research Councils. All Rights Reserved.