uk.ac.starlink.table.join

Interface HealpixMask

All Known Implementing Classes:

BitsetMask

public interface HealpixMask

Represents an area on the sky using HEALPix tesselation. On construction, the area is empty.

This interface defines what is required for use by the SkyCoverage class. The defined behaviour is somewhat like a MOC, and can be implemented using a MOC, but standard MOC implementations may not have suitable performance characteristics; in particular the addPixel(int, long) method ought to be fast.

Since:

8 Jun 2022

Author:

Mark Taylor

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	HealpixMask.PixelTester Defines a way to test inclusion of HEALPix pixels in an area.

Method Summary

Modifier and Type	Method and Description
void	addPixel(int order, long ipix) Adds the area corresponding to a HEALPix pixel to this mask.
HealpixMask.PixelTester	createPixelTester() Returns an object that can test inclusion in the sky area defined by the current state of this mask.
double	getSkyFraction() Returns the fraction of the sky currently covered by this mask.
void	intersection(HealpixMask other) Narrows this area to represent the intersection of this mask and another compatible mask.
boolean	isEmpty() Returns true if this mask's area is empty.
void	union(HealpixMask other) Extends this area to represent the union of this mask and another compatible mask.

Method Detail

isEmpty

boolean isEmpty()

Returns true if this mask's area is empty.

Returns:

true iff the createPixelTester() test is guaranteed to return false

intersection

void intersection(HealpixMask other)

Narrows this area to represent the intersection of this mask and another compatible mask.

Parameters:

other - different mask of a type assumed compatible with this one

union

void union(HealpixMask other)

Extends this area to represent the union of this mask and another compatible mask.

Parameters:

other - different mask of a type assumed compatible with this one

getSkyFraction

double getSkyFraction()

Returns the fraction of the sky currently covered by this mask.

Returns:

sky fraction between 0 and 1

addPixel

void addPixel(int order,
              long ipix)

Adds the area corresponding to a HEALPix pixel to this mask.

Parameters:

order - HEALPix order

ipix - HEALPix pixel index at order order

createPixelTester

HealpixMask.PixelTester createPixelTester()

Returns an object that can test inclusion in the sky area defined by the current state of this mask.

Returns:

thread-safe test for sky area inclusion