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From Jan Kotek <openco...@gmail.com>
Subject Spatial indexing with Healpix
Date Mon, 16 Feb 2009 22:01:55 GMT
Hello,

I am working on spatial indexing for Derby using Healpix:
http://healpix.jpl.nasa.gov/.

It is way to split sphere into pixels and number them. Pixel numbers
are associative (near locations have near numerical values). And can
be stored in long column with btree index. Pixel resolution can be
choosed, maximum is 0.2 arcsec.

Healpix was originally developed for astronomy. My program is also
astronomical application. But it works for geographical coordinates as
well.

Currently I implemented spatial indexing using 1:N table. But on high
resolutions it generates too much rows (one for each pixel). So next
step is range set, to reduce number of rows.

Related code is relatively simple and compact. If someone wants help,
it would be very welcomed.

Jan Kotek
http://kotek.net/opencoeli.

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