Package uk.ac.starlink.ttools.plot2

Class CdsHealpixUtil

  • public class CdsHealpixUtil
extends java.lang.Object
    Utilities for working with the cds-healpix-java library in sky plots.
    Since:
    21 May 2020
    Author:
    Mark Taylor

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int DFLT_INTERPOLATE_DEPTH
      Default minimum interpolation for HEALPix tile edges.

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static java.util.Set<java.lang.Long> bmocSet​(cds.healpix.HealpixNestedBMOC bmoc)
      Represents the tiles in a BMOC as a Set of Longs.
      static double[] lonlatToVector​(double[] lonlatRad)
      Converts a longitude, latitude 2-vector to a unit vector suitable for use as a sky surface data position, returning the result as a new array.
      static void lonlatToVector​(double[] lonlatRad, double[] xyz)
      Converts a longitude, latitude 2-vector to a unit vector suitable for use as a sky surface data position, writing the result to a supplied array.
      static void lonlatToVector​(double lonRad, double latRad, double[] xyz)
      Converts a longitude, latitude pair to a unit vector suitable for use as a sky surface data position, writing the result to a supplied array.
      static double[][] lonlatVertices​(cds.healpix.VerticesAndPathComputer vpc, long hash, int minDepth)
      Calculates vertices round the edge of a HEALPix tile, returning the result in a new array.
      static int lonlatVertices​(cds.healpix.VerticesAndPathComputer vpc, long hash, int minDepth, double[][] lonlats)
      Calculates vertices round the edge of a HEALPix tile, writing the result in a supplied array.
      static long vectorToHash​(cds.healpix.HashComputer hasher, double[] xyz)
      Calculates the tile index given a sky surface position unit vector.
      static double[] vectorToLonlat​(double[] xyz)
      Converts a sky surface data position unit vector to a longitude, latitude 2-vector, returning the restult as a new array.
      static void vectorToLonlat​(double[] xyz, double[] lonlatRad)
      Converts a sky surface data position unit vector to a longitude, latitude 2-vector, writing the result to a supplied array.

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • DFLT_INTERPOLATE_DEPTH

        public static final int DFLT_INTERPOLATE_DEPTH
        Default minimum interpolation for HEALPix tile edges.
        See Also:
        Constant Field Values

    • Method Detail

      • lonlatToVector

        public static void lonlatToVector​(double lonRad,
                                  double latRad,
                                  double[] xyz)
        Converts a longitude, latitude pair to a unit vector suitable for use as a sky surface data position, writing the result to a supplied array. No error checking is done.
        Parameters:
        lonRad - longitude in radians
        latRad - latitude in radians
        xyz - 3-element vector into which (x,y,z) is written

      • lonlatToVector

        public static void lonlatToVector​(double[] lonlatRad,
                                  double[] xyz)
        Converts a longitude, latitude 2-vector to a unit vector suitable for use as a sky surface data position, writing the result to a supplied array. No error checking is done.
        Parameters:
        lonlatRad - 2-element vector giving (longitude,latitude) in radians
        xyz - 3-element vector into which (x,y,z) is written

      • lonlatToVector

        public static double[] lonlatToVector​(double[] lonlatRad)
        Converts a longitude, latitude 2-vector to a unit vector suitable for use as a sky surface data position, returning the result as a new array. No error checking is done.
        Parameters:
        lonlatRad - 2-element vector giving (longitude,latitude) in radians
        Returns:
        3-element unit vector containing (x,y,z)

      • vectorToHash

        public static long vectorToHash​(cds.healpix.HashComputer hasher,
                                double[] xyz)
        Calculates the tile index given a sky surface position unit vector.
        Parameters:
        xyz - 3-element unit vector containing (x,y,z)

      • vectorToLonlat

        public static void vectorToLonlat​(double[] xyz,
                                  double[] lonlatRad)
        Converts a sky surface data position unit vector to a longitude, latitude 2-vector, writing the result to a supplied array. No error checking is done.
        Parameters:
        xyz - 3-element array containing (x,y,z)
        lonlatRad - 2-element array into which (longitude, latitude) in radians is written

      • vectorToLonlat

        public static double[] vectorToLonlat​(double[] xyz)
        Converts a sky surface data position unit vector to a longitude, latitude 2-vector, returning the restult as a new array. No error checking is done.
        Parameters:
        xyz - 3-element unit vector containing (x,y,z)
        Returns:
        2-element array giving (longitude, latitude) in radians

      • bmocSet

        public static java.util.Set<java.lang.Long> bmocSet​(cds.healpix.HealpixNestedBMOC bmoc)
        Represents the tiles in a BMOC as a Set of Longs. The returned object is a thin adapter on top of the input BMOC.
        Parameters:
        bmoc - result of healpix query
        Returns:
        set of hashes at BMOC depth

      • lonlatVertices

        public static int lonlatVertices​(cds.healpix.VerticesAndPathComputer vpc,
                                 long hash,
                                 int minDepth,
                                 double[][] lonlats)
        Calculates vertices round the edge of a HEALPix tile, writing the result in a supplied array. This convenience method just simplifies the required parameters.
        Parameters:
        vpc - healpix object that does the work
        hash - tile index
        minDepth - the minimal depth at which vertices are calculated; if the tile depth is greater or equal to this value then 4 vertices will be calculated, otherwise interpolated points will be included
        lonlats - [N][2]-element array into which pairs of (longitude,latitude) in radians will be written
        Returns:
        number of vertices written into lonlats

      • lonlatVertices

        public static double[][] lonlatVertices​(cds.healpix.VerticesAndPathComputer vpc,
                                        long hash,
                                        int minDepth)
        Calculates vertices round the edge of a HEALPix tile, returning the result in a new array. This convenience method just simplifies the required parameters.
        Parameters:
        vpc - healpix object that does the work
        hash - tile index
        minDepth - the minimal depth at which vertices are calculated; if the tile depth is greater or equal to this value then 4 vertices will be calculated, otherwise interpolated points will be included
        Returns:
        array of (longitude,latitude) pairs in radians