Package uk.ac.starlink.ttools.cone
Class HealpixTiling
java.lang.Object
uk.ac.starlink.ttools.cone.HealpixTiling
- All Implemented Interfaces:
SkyTiling
Tiling implementation based on the HEALPix scheme.
- Since:
- 12 Dec 2007
- Author:
- Mark Taylor
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final int
Maximum healpix level permitted by CDS Healpix implementation (29). -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionint
Returns the HEALpix level.uk.ac.starlink.table.ValueInfo
Returns a metadata item suitable for describing the pixel index used by this tiling.long
Returns the total number of tiles in this tiling.long
getPositionTile
(double ra, double dec) Returns the index of the tile in which a given sky position falls.long[]
getTileRange
(double ra, double dec, double radius) Returns the bounds of a range of pixels which is known to cover a given cone on the sky.boolean
isNest()
Indicates HEALPix ordering scheme.
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Field Details
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MAX_LEVEL
public static final int MAX_LEVELMaximum healpix level permitted by CDS Healpix implementation (29).- See Also:
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Constructor Details
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HealpixTiling
public HealpixTiling(int k, boolean nest) Constructor.- Parameters:
k
- Healpix levelnest
- true for nesting scheme, false for ring scheme
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Method Details
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getHealpixK
public int getHealpixK()Returns the HEALpix level.- Returns:
- log2(nside)
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isNest
public boolean isNest()Indicates HEALPix ordering scheme.- Returns:
- true for NEST, false for RING
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getPixelCount
public long getPixelCount()Description copied from interface:SkyTiling
Returns the total number of tiles in this tiling. Tile indices are assumed to be in the range from zero (inclusive) to this value (exclusive), so the returned value is one greater than the maximum tile index.- Specified by:
getPixelCount
in interfaceSkyTiling
- Returns:
- pixel count
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getIndexInfo
public uk.ac.starlink.table.ValueInfo getIndexInfo()Description copied from interface:SkyTiling
Returns a metadata item suitable for describing the pixel index used by this tiling.- Specified by:
getIndexInfo
in interfaceSkyTiling
- Returns:
- tile index metadata
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getPositionTile
public long getPositionTile(double ra, double dec) Description copied from interface:SkyTiling
Returns the index of the tile in which a given sky position falls.- Specified by:
getPositionTile
in interfaceSkyTiling
- Parameters:
ra
- right ascension in degreesdec
- declination in degrees- Returns:
- tile index for position
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getTileRange
public long[] getTileRange(double ra, double dec, double radius) Description copied from interface:SkyTiling
Returns the bounds of a range of pixels which is known to cover a given cone on the sky. The return value is a two-element array, (lo,hi). Every point in the specified cone must have a tile index which is greater than or equal to the first element of that array, and less than or equal to the second element. If the question cannot be answered, or if the range is thought to be too large to be of use (for instance, if it would take a long time to calculate), thennull
may be returned.- Specified by:
getTileRange
in interfaceSkyTiling
- Parameters:
ra
- right ascension in degreesdec
- declination in degreesradius
- radius in degrees- Returns:
- 2-element array giving inclusive (low, high) bounds of tile range covering the cone
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