Native support for MOC operations in the Java HEALPix package

[Martin Reinecke]

Hi,

I was encouraged by Pierre Fernique to send this announcement to the
IVOA apps mailing list, since there might be broader interest ...


After the MOC standard document had been accepted, I started working on
native MOC support in the Java HEALPix package.
My aim was to provide a compact and highly efficient implementation of
the central functionality (MOC construction, input/output and set
operations). Here is a fairly complete list of the current capabilities:

- import/export from/to FITS (both files and streams are supported)

- import/export from/to strings (both the basic ASCII and JSON syntax
shown in the MOC standard)

- import/export from/to a highly compressed bitstream representation,
making use of interpolative coding. These objects are significantly
smaller than the FITS and ASCII representations, and can be read/written
very quickly; they could be useful on a VO server dealing with many MOCs
at the same time.

- import/export from/to RangeSets of UNIQ pixels

- set operations (union, intersection, subtraction, overlap test, subset
test, complement) that are even faster than what was available so far,
due to improvements in the RangeSet class.

- resolution degradation of a MOC to a desired Healpix order. Partially
covered pixels can be kept or discarded, depending on a parameter.

If you are interested, I have attached a source tarball of the current
Java HEALPix package. The most up-to-date version can always be found in
the subversion repository at http://sourceforge.net/projects/healpix

Please let me know if you think that essential functionality is still
missing!
Concerning class and function names, I'm still considering various
alternatives to make them as unambiguous as possible. Again, if you have
suggestions in that area, please tell me.

Best regards,
  Martin Reinecke

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