http://lucene.apache.org/lucene-parent/lucene-spatial-extras: Advanced Spatial Shape Strategies for Apache Lucene (The Apache Software Foundation) 
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
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This package is about SpatialPrefixTree and any supporting classes.
A SpatialPrefixTree supports spatial indexing by index-time tokens
where adding characters to a string gives greater resolution.


Potential Implementations include:

    

  • http://en.wikipedia.org/wiki/Quadtree

  • http://en.wikipedia.org/wiki/Geohash

  • http://healpix.jpl.nasa.gov/



/**
 * This package is about SpatialPrefixTree and any supporting classes.
 * A SpatialPrefixTree supports spatial indexing by index-time tokens
 * where adding characters to a string gives greater resolution.
 * <p>
 * Potential Implementations include:
 * <ul>
 * <li>http://en.wikipedia.org/wiki/Quadtree
 * <li>http://en.wikipedia.org/wiki/Geohash
 * <li>http://healpix.jpl.nasa.gov/
 * </ul>
 */
package org.apache.lucene.spatial.prefix.tree;