uk.ac.starlink.table.join
Class PixtoolsHealpixSkyPixellator

java.lang.Object
  uk.ac.starlink.table.join.HealpixSkyPixellator
      uk.ac.starlink.table.join.PixtoolsHealpixSkyPixellator

All Implemented Interfaces:

SkyPixellator

public class PixtoolsHealpixSkyPixellator
extends HealpixSkyPixellator

HEALPix sky pixellator using the PixTools library. This implementation is based on the PixTools Java HEALPix classes written by Nickolai Kouropatkine at Fermilab. The maximum K value is 20.

See Also:

http://home.fnal.gov/~kuropat/HEALPIX/PixTools.html

Constructor Summary

PixtoolsHealpixSkyPixellator()
Constructs a pixellator using the default scheme (RING).

PixtoolsHealpixSkyPixellator(boolean nested)
Constructs a pixellator using either the RING or NESTED HEALPix scheme.

Method Summary

int	calculateDefaultK(double scale) Determines a default value to use for the HEALPix k parameter based on a given scale.
protected void	configureK(int k) Updates internal state for the current value of the k parameter.
java.lang.Object[]	getPixels(double alpha, double delta, double radius) Returns an array of objects representing pixels in a given region.

Methods inherited from class uk.ac.starlink.table.join.HealpixSkyPixellator

getHealpixK, getMaxK, getScale, getTuningParameter, setHealpixK, setScale

Methods inherited from class java.lang.Object

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

Constructor Detail

PixtoolsHealpixSkyPixellator

public PixtoolsHealpixSkyPixellator(boolean nested)

Constructs a pixellator using either the RING or NESTED HEALPix scheme.

Parameters:

nested - false for RING scheme, true for NESTED

PixtoolsHealpixSkyPixellator

public PixtoolsHealpixSkyPixellator()

Constructs a pixellator using the default scheme (RING).

Method Detail

getPixels

public java.lang.Object[] getPixels(double alpha,
                                    double delta,
                                    double radius)

Description copied from interface: SkyPixellator

Returns an array of objects representing pixels in a given region. The parameters specify a small circle on the sphere; any pixels which overlap this circle must be returned (additional pixels may also be returned). The output objects are of some opaque type, but must implement the equals and hashCode methods appropriately, so that objects returned from one call can be compared for identity with objects returned from a subsequent call. This comparability is only guaranteed to work if the pixel scale is not changed in between calls.

Parameters:

alpha - right ascension of circle centre in radians

delta - declination of circle centre in radians

radius - radius of circle in radians

Returns:

array of opaque but comparable pixel objects

configureK

protected void configureK(int k)

Description copied from class: HealpixSkyPixellator

Updates internal state for the current value of the k parameter.

Specified by:

configureK in class HealpixSkyPixellator

Parameters:

k - HEALPix order

calculateDefaultK

public int calculateDefaultK(double scale)

Determines a default value to use for the HEALPix k parameter based on a given scale.

Specified by:

calculateDefaultK in class HealpixSkyPixellator

Parameters:

scale - distance scale, in radians