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From "David Smiley (JIRA)" <>
Subject [jira] [Created] (LUCENE-4900) Add spatial edge approximations: include/exclude/center
Date Wed, 03 Apr 2013 14:51:16 GMT
David Smiley created LUCENE-4900:

             Summary: Add spatial edge approximations: include/exclude/center
                 Key: LUCENE-4900
             Project: Lucene - Core
          Issue Type: New Feature
          Components: modules/spatial
            Reporter: David Smiley
            Priority: Minor

The RecursivePrefixTree predicates incidentally buffer the query shape slightly to your specifications
(distErr, distErrPct) as a byproduct of fitting it to a grid, thus making the search area
slightly (or not so slightly) larger than the given shape.  Because of the grid approximation,
some amount of this is unavoidable.  The result is that these predicates can match some false-positives
that are slightly outside the query shape.  The user might want instead to not match those
false positives on the edge at all and is willing to accept the reverse inaccuracy -- not
matching false-negatives i.e. sort of reverse-buffering the shape edge. Or the user might
instead want to substitute the center point of the a cell at the shape's edge to detect if
it's a match or not -- thus some false-positives will match and some false-negatives won't
match but at a higher detail.

Based on the way these predicates are implemented, it'd be pretty easy to add support for
these conditions.  Arguably there is an index-time analog to this idea as well but that'd
be harder.

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