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Date: Tue, 23 Apr 2013 15:27:15 +0000 (UTC)
From: "David Smiley (JIRA)" <jira@apache.org>
To: dev@lucene.apache.org
Message-ID: <JIRA.12641676.1365530943467.208457.1366730835822@arcas>
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Subject: [jira] [Commented] (LUCENE-4922) A SpatialPrefixTree based on the
 Hilbert Curve and variable grid sizes
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    [ https://issues.apache.org/jira/browse/LUCENE-4922?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13639152#comment-13639152 ] 

David Smiley commented on LUCENE-4922:
--------------------------------------

Thanks for the proposal Hatim!  That's a good proposal.  I enjoyed reading some of the research papers you referenced.  I'm excited to think that at the end of the summer, there's going to be an awesome optimized PrefixTree; and I'm a tad jealous that a lucky student is going to build it instead of me :-) 

p.s. I independently developed my own outline of tasks to do, which I'll share with the student that is accepted (which is likely you but theoretically could be another student if there is interest from others)
                
> A SpatialPrefixTree based on the Hilbert Curve and variable grid sizes
> ----------------------------------------------------------------------
>
>                 Key: LUCENE-4922
>                 URL: https://issues.apache.org/jira/browse/LUCENE-4922
>             Project: Lucene - Core
>          Issue Type: New Feature
>          Components: modules/spatial
>            Reporter: David Smiley
>            Assignee: David Smiley
>              Labels: gsoc2013, mentor, newdev
>
> My wish-list for an ideal SpatialPrefixTree has these properties:
> * Hilbert Curve ordering
> * Variable grid size per level (ex: 256 at the top, 64 at the bottom, 16 for all in-between)
> * Compact binary encoding (so-called "Morton number")
> * Works for geodetic (i.e. lat & lon) and non-geodetic
> Some bonus wishes for use in geospatial:
> * Use an equal-area projection such that each cell has an equal area to all others at the same level.
> * When advancing a grid level, if a cell's width is less than half its height. then divide it as 4 vertically stacked instead of 2 by 2. The point is to avoid super-skinny cells which occurs towards the poles and degrades performance.
> All of this requires some basic performance benchmarks to measure the effects of these characteristics.

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