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From "Hatim Hakeel (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-4922) A SpatialPrefixTree based on the Hilbert Curve and variable grid sizes
Date Fri, 12 Apr 2013 05:29:16 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-4922?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13629809#comment-13629809
] 

Hatim Hakeel commented on LUCENE-4922:
--------------------------------------

Hi David,

I believe this would require to implement a class that extends the SpatialPrefixTree class.
It should support all porperties mentioned. We get it to perform Hilbert space filling curve
based spatial data structure traversal in making range queries etc.
Apart from performance benchmarks to measure effects of the new feature, are the bonus wishes
for use in geospatial to be considered as optimizations given availability of time?

Thanks,
Hatim.
                
> 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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