Package uk.ac.starlink.ttools.cone

Class HealpixTiling

  • All Implemented Interfaces:
    SkyTiling
    public class HealpixTiling
extends java.lang.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 int MAX_LEVEL
      Maximum healpix level permitted by PixTools implementation (20).

    • Constructor Summary

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

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      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 Detail

      • MAX_LEVEL

        public static final int MAX_LEVEL
        Maximum healpix level permitted by PixTools implementation (20).
        See Also:
        Constant Field Values

    • Constructor Detail

      • HealpixTiling

        public HealpixTiling​(int k,
                     boolean nest)
        Constructor.
        Parameters:
        k - log to base 2 of HEALPix Nside parameter
        nest - true for nesting scheme, false for ring scheme

    • Method Detail

      • 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