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17<html>
18  <head>
19    <title>Apache Lucene Spatial-Extras Module</title>
20  </head>
21  <body>
22
23  <h1>The Spatial-Extras Module for Apache Lucene</h1>
24
25  <p>
26    The spatial-extras module, new to Lucene 6.5, is the new home for the original
27    lucene spatial module.
28    The principle interface to this module is a {@link org.apache.lucene.spatial.SpatialStrategy}
29    which encapsulates an approach to indexing and searching
30    based on shapes.  Different Strategies have different features and
31    performance profiles, which are documented at each Strategy implementation
32    class level.
33  </p>
34  <p>
35    For some sample code showing how to use the API, see
36      SpatialExample.java in the tests.
37  </p>
38<p>
39    The spatial-extras module uses
40    <a href="https://github.com/spatial4j/spatial4j">Spatial4j</a>
41    heavily.  Spatial4j is an ASL licensed library with these capabilities:
42    <ul>
43    <li>Provides shape implementations, namely point, rectangle,
44      and circle.  Both geospatial contexts and plain 2D Euclidean/Cartesian contexts
45      are supported.
46      With an additional dependency, it adds polygon and other geometry shape
47      support via integration with
48      <a href="http://sourceforge.net/projects/jts-topo-suite/">JTS Topology Suite</a>.
49      This includes dateline wrap support.</li>
50    <li>Shape parsing and serialization, including
51      <a href="http://en.wikipedia.org/wiki/Well-known_text">Well-Known Text (WKT)</a>
52      (via JTS).</li>
53    <li>Distance and other spatial related math calculations.</li>
54    </ul>
55  <p>
56    Historical note: The new spatial-extras module was once known as
57    Lucene Spatial Playground (LSP) as an external project.  In ~March 2012, LSP
58    split into the spatial module as part of Lucene and Spatial4j externally. A
59    large chunk of the LSP implementation originated as SOLR-2155 which uses
60    trie/prefix-tree algorithms with a geohash encoding.  That approach is
61    implemented in {@link org.apache.lucene.spatial.prefix.RecursivePrefixTreeStrategy}
62    today.
63  </p>
64
65  </body>
66</html>
67