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Accumulo, mail # dev - Storing Geospatial Tiles in Accumulo Question


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Re: Storing Geospatial Tiles in Accumulo Question
Ed Kohlwey 2012-06-27, 12:01
David's trick is actually equivalent to a z order curve and a quadtree. Be
aware though that you can't increase magnitude in the portion above the
decimal without throwing the table off, so make sure you pick an
appropriate exponent and stick with it, zero padding out the part above the
decimal.

You can use this to store tiles if you want too, you just use a uniform
point such as the center or upper left hand corner on each tile as the
tile's position. If you address using the corners, you'll also want to use
something like the column family or qualifier to show what depth of the
tesselation you are at because using the corner will result in overlapping
tile addresses. If you need to address the tiles on some other dimension,
you can also use secondary indexing to store references to tiles for some
other purpose.

Sent from my smartphone. Please excuse any typos or shorthand.
On Jun 26, 2012 10:12 PM, "David Arsenault" <[EMAIL PROTECTED]> wrote:

> Susan
>
> Recently had a discussion about a great geo "trick" for Accumulo. As you
> know Accumulo maintains a sorted set of rows based on RowID, ColFam,
> ColQual. If you had data with LAT/LON values and you interlace the digits
> (fake coods example: lat 203.5, lon 127.1 --> 210237.51), it turns out that
> sorting keeps close points together in the table space. It only works for
> points not tiles, but perhaps you may want some analytics on center points
> of tiles or perhaps you want to efficiently index points of interest for
> structures or other features.
>
> Best,
> David Arsenault
> The MITRE Corporation
>
> Sent from my iPad
>
> On Jun 26, 2012, at 9:31, "Thistlethwaite, Susan - IS" <
> [EMAIL PROTECTED]> wrote:
>
> > ALCON:
> >
> > My team has been tasked with ingesting/retrieving geospatial tiles
> to/from Accumulo.
> >
> > I know others are using Z-Order or Hilbert Curves for storing geospatial
> points.  Do you know of others who are working with tiles/polygons/shape
> files?
> >
> > W/r
> > Susan Thistlethwaite
> > Software-Systems Engineer
> > ITT Exelis
> > 12975 Worldgate Dr.
> > Herndon, VA 20170
> > 571-332-2662 cell
> > 703-668-6539 office
> > [EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]> email
> >
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