Package uk.ac.starlink.ttools.cone

Class HealpixTiling

java.lang.Object
uk.ac.starlink.ttools.cone.HealpixTiling
All Implemented Interfaces:
SkyTiling
public class HealpixTiling extends Object implements SkyTiling
Tiling implementation based on the HEALPix scheme.
Since:
12 Dec 2007
Author:
Mark Taylor

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    MAX_LEVEL
    Maximum healpix level permitted by CDS Healpix implementation (29).

  • Constructor Summary

    Constructors
    Constructor
    Description
    HealpixTiling(int k, boolean nest)
    Constructor.

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    getHealpixK()
    Returns the HEALpix level.
    uk.ac.starlink.table.ValueInfo
    getIndexInfo()
    Returns a metadata item suitable for describing the pixel index used by this tiling.
    long
    getPixelCount()
    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.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • MAX_LEVEL

      public static final int MAX_LEVEL
      Maximum healpix level permitted by CDS Healpix implementation (29).
      See Also:

  • Constructor Details

    • HealpixTiling

      public HealpixTiling(int k, boolean nest)
      Constructor.
      Parameters:
      k - Healpix level
      nest - true for nesting scheme, false for ring scheme

  • Method Details

    • getHealpixK

      public int getHealpixK()
      Returns the HEALpix level.
      Returns:
      log2(nside)

    • isNest

      public boolean isNest()
      Indicates HEALPix ordering scheme.
      Returns:
      true for NEST, false for RING

    • 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 interface SkyTiling
      Returns:
      pixel count

    • 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 interface SkyTiling
      Returns:
      tile index metadata

    • 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 interface SkyTiling
      Parameters:
      ra - right ascension in degrees
      dec - declination in degrees
      Returns:
      tile index for position

    • 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), then null may be returned.
      Specified by:
      getTileRange in interface SkyTiling
      Parameters:
      ra - right ascension in degrees
      dec - declination in degrees
      radius - radius in degrees
      Returns:
      2-element array giving inclusive (low, high) bounds of tile range covering the cone