Geohash

水深无声 2022-08-07 09:55 163阅读 0赞

# Geohash #

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This article is about a system for encoding geographic coordinates. For the game, see [ Geohashing][Geohashing].

**Geohash** is a [ latitude][latitude]/[longitude][] [ geocode][geocode] system invented by [ Gustavo Niemeyer][Gustavo Niemeyer] when writing the web service at *[geohash.org][]*, and put into the public domain. It is a hierarchical spatial data structure which subdivides space into buckets of [ grid][grid] shape.

Geohashes offer properties like arbitrary precision and the possibility of gradually removing characters from the end of the code to reduce its size (and gradually lose precision).

As a consequence of the gradual precision degradation, nearby places will often (but not always) present similar prefixes. The longer a shared prefix is, the closer the two places are.

## Contents ##

\[[hide][]\]

*  [1 Service][]
 *  [2 Uses][]
 *  [3 Example][]
    
     *  [3.1 Decode from base 32][]
     *  [3.2 Decode binary to decimal][]
     *  [3.3 Worked example][]
 *  [4 Limitations][]
 *  [5 License and patents][]
 *  [6 See also][]
 *  [7 External links][]
 *  [8 References][]

## Service\[[edit][]\] ##

The purpose of the *geohash.org* service, launched in February 2008, is to offer short [ URLs][URLs] which uniquely identify positions on the [ Earth][Earth], so that referencing them in [ emails][emails], [ forums][forums], and [ websites][websites] is more convenient.

To obtain the Geohash, the user provides an address to be [ geocoded][geocode], or [ latitude][latitude] and [ longitude][longitude] coordinates, in a single input box (most commonly used formats for latitude and longitude pairs are accepted), and performs the request.

Besides showing the latitude and longitude corresponding to the given Geohash, users who navigate to a Geohash at geohash.org are also presented with an embedded map, and may download a [ GPX][GPX] file, or transfer the waypoint directly to certain [ GPS][GPS] receivers. Links are also provided to external sites that may provide further details around the specified location.

For example, the coordinate pair **57.64911,10.40744** (near the tip of the [ peninsula][peninsula] of [ Jutland][Jutland], in [ Denmark][Denmark]) produces a slightly shorter hash of **u4pruydqqvj**, which can be used in the URL [ http://geohash.org/u4pruydqqvj][http_geohash.org_u4pruydqqvj]

## Uses\[[edit][edit 1]\] ##

The main usages of Geohashes are

*  as a unique identifier.
 *  represent point data e.g. in databases.

Geohashes have also been proposed to be used for [ geotagging][geotagging].

When used in a database, the structure of geohashed data has two advantages. First, data indexed by geohash will have all points for a given rectangular area in contiguous slices (the number of slices depends on the precision required and the presence of geohash "fault lines"). This is especially useful in database systems where queries on a single index are much easier or faster than multiple-index queries. Second, this index structure can be used for a quick-and-dirty proximity search - the closest points are often among the closest geohashes. Another system known as [ GeoZip][GeoZip] might provide a simpler way of achieving similar results if the application does not require the resulting code to be in a compressed format. This claim made by the GeoZip inventor has not been verified yet.

## Example\[[edit][edit 2]\] ##

Using the hash *ezs42* as an example, here is how it is decoded into a decimal latitude and longitude

### Decode from base 32\[[edit][edit 3]\] ###

The first step is decoding it from [ base 32][base 32] using the following character map:

<table> 
 <tbody> 
  <tr> 
   <th>Decimal</th> 
   <td>0</td> 
   <td>1</td> 
   <td>2</td> 
   <td>3</td> 
   <td>4</td> 
   <td>5</td> 
   <td>6</td> 
   <td>7</td> 
   <td>8</td> 
   <td>9</td> 
   <td>10</td> 
   <td>11</td> 
   <td>12</td> 
   <td>13</td> 
   <td>14</td> 
   <td>15</td> 
  </tr> 
  <tr> 
   <th>Base 32</th> 
   <td>0</td> 
   <td>1</td> 
   <td>2</td> 
   <td>3</td> 
   <td>4</td> 
   <td>5</td> 
   <td>6</td> 
   <td>7</td> 
   <td>8</td> 
   <td>9</td> 
   <td>b</td> 
   <td>c</td> 
   <td>d</td> 
   <td>e</td> 
   <td>f</td> 
   <td>g</td> 
  </tr> 
  <tr> 
   <td colspan="20" style="font:0.5em/0.5em serif">&nbsp;</td> 
  </tr> 
  <tr> 
   <th>Decimal</th> 
   <td>16</td> 
   <td>17</td> 
   <td>18</td> 
   <td>19</td> 
   <td>20</td> 
   <td>21</td> 
   <td>22</td> 
   <td>23</td> 
   <td>24</td> 
   <td>25</td> 
   <td>26</td> 
   <td>27</td> 
   <td>28</td> 
   <td>29</td> 
   <td>30</td> 
   <td>31</td> 
  </tr> 
  <tr> 
   <th>Base 32</th> 
   <td>h</td> 
   <td>j</td> 
   <td>k</td> 
   <td>m</td> 
   <td>n</td> 
   <td>p</td> 
   <td>q</td> 
   <td>r</td> 
   <td>s</td> 
   <td>t</td> 
   <td>u</td> 
   <td>v</td> 
   <td>w</td> 
   <td>x</td> 
   <td>y</td> 
   <td>z</td> 
  </tr> 
 </tbody> 
</table>

This operation results in the [ bits][bits] 01101 11111 11000 00100 00010. Assuming that counting starts at 0 in the left side, the even bits are taken for the longitude code (0111110000000), while the odd bits are taken for the latitude code (101111001001).

### Decode binary to decimal\[[edit][edit 4]\] ###

Each binary code is then used in a series of divisions, considering one bit at a time, again from the left to the right side. For the latitude value, the interval -90 to +90 is divided by 2, producing two intervals: -90 to 0, and 0 to +90. Since the first bit is 1, the higher interval is chosen, and becomes the current interval. The procedure is repeated for all bits in the code. Finally, the latitude value is the center of the resulting interval. Longitudes are processed in an equivalent way, keeping in mind that the initial interval is -180 to +180.

Finishing the procedure should yield approximately latitude 42.6 and longitude -5.6.

### Worked example\[[edit][edit 5]\] ###

Here's a worked example decoding 101111001001 into 42.6. To start with, we know the latitude is somewhere in the range −90 to 90. With no bits, we'd have to guess the latitude was 0, giving us an error of ±90. With one bit, we can decide whether its in the range −90 to 0, or 0 to 90. The first bit is high, so we know our latitude is somewhere between 0 and 90. Without any more bits, we'd guess the latitude was 45, giving us an error of ±45.

Each subsequent bit halves this error. This table shows the effect of each bit. At each stage, the relevant half of the range is highlighted in green; a low bit selects the lower range, a high bit selects the upper range.

The last column shows the latitude, simply the mean value of the range. Each subsequent bit makes this value more precise.

(The numbers in the above table have been rounded to 3 decimal places for clarity)

Final rounding should be done carefully in a way that

![\\min \\le \\mathrm\{round\}(value) \\le \\max][min _le _mathrm_round_value_ _le _max]

So if rounding 42.605 to 42.61 or 42.6 is correct, rounding to 43 it is not.

<table> 
 <tbody> 
  <tr> 
   <th>geohash length</th> 
   <th>lat bits</th> 
   <th>lng bits</th> 
   <th>lat error</th> 
   <th>lng error</th> 
   <th>km error</th> 
  </tr> 
  <tr> 
   <td>1</td> 
   <td>2</td> 
   <td>3</td> 
   <td>±23</td> 
   <td>±23</td> 
   <td>±2500</td> 
  </tr> 
  <tr> 
   <td>2</td> 
   <td>5</td> 
   <td>5</td> 
   <td>± 2.8</td> 
   <td>± 5.6</td> 
   <td>±630</td> 
  </tr> 
  <tr> 
   <td>3</td> 
   <td>7</td> 
   <td>8</td> 
   <td>± 0.70</td> 
   <td>± 0.7</td> 
   <td>±78</td> 
  </tr> 
  <tr> 
   <td>4</td> 
   <td>10</td> 
   <td>10</td> 
   <td>± 0.087</td> 
   <td>± 0.18</td> 
   <td>±20</td> 
  </tr> 
  <tr> 
   <td>5</td> 
   <td>12</td> 
   <td>13</td> 
   <td>± 0.022</td> 
   <td>± 0.022</td> 
   <td>±2.4</td> 
  </tr> 
  <tr> 
   <td>6</td> 
   <td>15</td> 
   <td>15</td> 
   <td>± 0.0027</td> 
   <td>± 0.0055</td> 
   <td>±0.61</td> 
  </tr> 
  <tr> 
   <td>7</td> 
   <td>17</td> 
   <td>18</td> 
   <td>±0.00068</td> 
   <td>±0.00068</td> 
   <td>±0.076</td> 
  </tr> 
  <tr> 
   <td>8</td> 
   <td>20</td> 
   <td>20</td> 
   <td>±0.000085</td> 
   <td>±0.00017</td> 
   <td>±0.019</td> 
  </tr> 
 </tbody> 
</table>

## Limitations\[[edit][edit 6]\] ##

One limitation of the Geohash algorithm is in attempting to utilize it to find points in proximity to each other based on a common prefix. [ Edge case][Edge case] locations close to each other but on opposite sides of the 180 degree meridian will result in Geohash codes with no common prefix (different longitudes for near physical locations). Points close by at the North and South poles will have very different geohashes (different latitudes for near physical locations).

Two close locations on either side of the Equator (or Greenwich meridian) will not have a long common prefix since they belong to different 'halves' of the world. Put simply, one location's binary latitude (or longitude) will be 011111... and the other 100000...., so they will not have a common prefix and most bits will be flipped. This can also be seen as a consequence of relying on the [ Z-order curve][Z-order curve] for ordering the points, as two points close-by might be visited at very different times. However, two points with a long common prefix will be close-by.

In order to do a proximity search, one could compute the southwest corner (low geohash with low latitude and longitude) and northeast corner (high geohash with high latitude and longitude) of a bounding box and search for geohashes between those two. This will retrieve all points in the z-order curve between the two corners, which can be far too many points, this also breaks down at the 180 meridians and the poles. Solr uses a filter list of prefixes, by computing the prefixes of the nearest squares close to the geohash [ \[1\]][_1].

Thirdly, since a geohash (in this implementation) is based on [ coordinates of longitude and latitude][coordinates of longitude and latitude] the distance between two geohashes reflects the distance in latitude/longitude coordinates between two points, which does not translate to actual distance, see [ Haversine formula][Haversine formula].

Example of non-linearity for latitude-longitude system:

*  At the Equator (0 Degrees) the length of a degree of longitude is 111.320 km, while a degree of latitude measures 110.574 km, an error of 0.67%.
 *  At 30 Degrees (Mid Latitudes) the error is 110.852/96.486 = 14.89%
 *  At 60 Degrees (High Arctic) the error is 111.412/55.800 = 99.67%, reaching infinity at the poles.

Note that these limitations are not due to geohashing, and not due to latitude-longitude coordinates, but due to the difficulty of mapping coordinates on a sphere (non linear and with wrapping of values, similar to modulo arithmetic) to two dimensional coordinates and the difficulty of exploring a two dimensional space uniformly. The first is related to [ Geographical coordinate system][coordinates of longitude and latitude] and [ Map projection][Map projection], and the other to [ Hilbert curve][Hilbert curve] and [ z-order curve][Z-order curve]. Once a coordinate system is found that represents points linearly in distance and wraps up at the edges, and can be explored uniformly, applying geohashing to those coordinates will not suffer from the limitations above.

While it is possible to apply geohashing to an area with a [ cartesian coordinate system][cartesian coordinate system], it would then only apply to the area where the coordinate system applies.

Despite those issues, there are possible workarounds, and the algorithm has been successfully used in Elasticsearch,[\[1\]][1] MongoDB,[\[2\]][2] HBase, and [ Accumulo][Accumulo][\[3\]][3] to implement proximity searches.

An alternative to storing Geohashes as strings in a database are [ Locational codes][Locational codes], which are also called spatial keys and similar to QuadTiles.[\[4\]][4][\[5\]][5]

## License and patents\[[edit][edit 7]\] ##

The Geohash geocode has been put in the [ public domain][public domain] by its inventor in the public announcement date, on February 26, 2008.[\[6\]][6]

While comparable algorithms have been successfully patented[\[7\]][7] and had copyright claimed upon,[\[8\]][8][\[9\]][9] GeoHash is based on an entirely different algorithm and approach.

## See also\[[edit][edit 8]\] ##

*  [Geohash-36][]
 *  [Grid (spatial index)][grid]
 *  [Morton number (number theory)][Morton number _number theory]
 *  [Natural Area Code][]
 *  [Maidenhead Locator System][]
 *  [Military grid reference system][]

## External links\[[edit][edit 9]\] ##

*  [geohash.org][]
 *  [elasticsearch: the definitive guide - Geo][elasticsearch_ the definitive guide - Geo]
 *  [Visualizing Geohash][]
 *  [Perl module to interact with geohash.org][]
 *  Libraries, packages and modules for encoding and decoding geohashes without interacting with geohash.org: [ in C][in C], [ Python][Python], [ Haskell][Haskell],

[Perl][], [ Ruby (Gem)][Ruby _Gem], [ Ruby][Ruby], [ Ocaml][Ocaml], [ Clojure][Clojure], [ Go][Go], [ Objective-C][Objective-C], [ Javascript][Javascript] ([Demo][]), [ PHP][PHP], [ MySQL][MySQL], [ PostGIS][PostGIS], [ nodejs][nodejs]

*  Java classes for encoding and decoding geohashes: [ geospatialweb][geospatialweb], [ jgeohash][jgeohash], [ geohash-java][geohash-java], and [ geo][geo]
 *  [kml file for Google Earth displaying geohash grid][]
 *  [Area Check Tool][]
 *  [\[2\]][2 1] \- [GeoMesa][] \- A spatio-temporal database using Geohashes and Accumulo
 *  [Simple and fast conversion from geohash to latitude/longitude and from latitude/longitude to geohash][Simple and fast conversion from geohash to latitude_longitude and from latitude_longitude to geohash]

## References\[[edit][edit 10]\] ##

1.  **[Jump up ^][Jump up]** [geo\_shape Type Mapping in Elasticsearch][geo_shape Type Mapping in Elasticsearch]
2.  **[Jump up ^][Jump up 1]** [Geospatial Indexing in MongoDB][]
3.  **[Jump up ^][Jump up 2]** [Spatio-temporal Indexing in Non-relational Distributed Databases][]
4.  **[Jump up ^][Jump up 3]** [Spatial Keys][]
5.  **[Jump up ^][Jump up 4]** [QuadTiles][]
6.  **[Jump up ^][Jump up 5]** [geohash.org announcement post in groundspeak.com forum][]
7.  **[Jump up ^][Jump up 6]** [Compact text encoding of latitude/longitude coordinates - Patent 20050023524][Compact text encoding of latitude_longitude coordinates - Patent 20050023524]
8.  **[Jump up ^][Jump up 7]** [Does Microsoft Infringe the Natural Area Coding System?][Does Microsoft Infringe the Natural Area Coding System]
9.  **[Jump up ^][Jump up 8]** [The Natural Area Coding System - Legal and Licensing][]

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       <th colspan="2"><span><span>[</span><a href="http://en.wikipedia.org/wiki/Geohash#" rel="nofollow">hide</a><span>]</span></span> 
        <div> 
         <ul> 
          <li><a title="Template:Geocoding-systems" href="http://en.wikipedia.org/wiki/Template:Geocoding-systems" rel="nofollow"><span title="View this template" style="background:none; border:currentColor">v</span></a> </li> 
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          <li><a href="http://en.wikipedia.org/w/index.php?title=Template:Geocoding-systems&amp;action=edit" rel="nofollow"><span title="Edit this template" style="background:none; border:currentColor">e</span></a> </li> 
         </ul> 
        </div> 
        <div style="font-size:110%"> 
         <a title="List of geocoding systems" href="http://en.wikipedia.org/wiki/List_of_geocoding_systems" rel="nofollow">Geocoding systems</a> 
        </div> </th> 
      </tr> 
      <tr style="height:2px"> 
       <td colspan="2"></td> 
      </tr> 
      <tr> 
       <th>Administrative codes</th> 
       <td style="padding:0px; width:100%; text-align:left; border-left-width:2px; border-left-style:solid"> 
        <div style="padding:0em 0.25em"> 
         <ul> 
          <li><a title="Hierarchical administrative subdivision codes" href="http://en.wikipedia.org/wiki/Hierarchical_administrative_subdivision_codes" rel="nofollow">HASC</a> </li> 
          <li><a title="Nomenclature of Territorial Units for Statistics" href="http://en.wikipedia.org/wiki/Nomenclature_of_Territorial_Units_for_Statistics" rel="nofollow">NUTS</a> (EU) </li> 
          <li><a title="ONS coding system" href="http://en.wikipedia.org/wiki/ONS_coding_system" rel="nofollow">ONS</a> </li> 
          <li><a title="MARC standards" href="http://en.wikipedia.org/wiki/MARC_standards" rel="nofollow">MARC country codes</a> </li> 
          <li><a title="Standard Geographical Classification code (Canada)" href="http://en.wikipedia.org/wiki/Standard_Geographical_Classification_code_%28Canada%29" rel="nofollow">SGC codes</a> (Canada) </li> 
          <li><a title="UN M.49" href="http://en.wikipedia.org/wiki/UN_M.49" rel="nofollow">UN M.49</a> (UN) </li> 
         </ul> 
        </div> </td> 
      </tr> 
      <tr style="height:2px"> 
       <td colspan="2">&nbsp;</td> 
      </tr> 
      <tr> 
       <th>Airport codes</th> 
       <td style="padding:0px; width:100%; text-align:left; border-left-width:2px; border-left-style:solid"> 
        <div style="padding:0em 0.25em"> 
         <ul> 
          <li><a title="International Air Transport Association airport code" href="http://en.wikipedia.org/wiki/International_Air_Transport_Association_airport_code" rel="nofollow">IATA airport code</a> </li> 
          <li><a title="International Civil Aviation Organization airport code" href="http://en.wikipedia.org/wiki/International_Civil_Aviation_Organization_airport_code" rel="nofollow">ICAO airport code</a> </li> 
         </ul> 
        </div> </td> 
      </tr> 
      <tr style="height:2px"> 
       <td colspan="2">&nbsp;</td> 
      </tr> 
      <tr> 
       <th>Country codes</th> 
       <td style="padding:0px; width:100%; text-align:left; border-left-width:2px; border-left-style:solid"> 
        <div style="padding:0em 0.25em"> 
         <ul> 
          <li><a title="Country code top-level domain" href="http://en.wikipedia.org/wiki/Country_code_top-level_domain" rel="nofollow">IANA country code</a> </li> 
          <li><a title="ISO 3166-1" href="http://en.wikipedia.org/wiki/ISO_3166-1" rel="nofollow">ISO 3166-1</a> 
           <ul> 
            <li><a title="ISO 3166-1 alpha-2" href="http://en.wikipedia.org/wiki/ISO_3166-1_alpha-2" rel="nofollow">alpha-2</a> </li> 
            <li><a title="ISO 3166-1 alpha-3" href="http://en.wikipedia.org/wiki/ISO_3166-1_alpha-3" rel="nofollow">alpha-3</a> </li> 
            <li><a title="ISO 3166-1 numeric" href="http://en.wikipedia.org/wiki/ISO_3166-1_numeric" rel="nofollow">numeric</a> </li> 
           </ul> </li> 
          <li><a title="List of IOC country codes" href="http://en.wikipedia.org/wiki/List_of_IOC_country_codes" rel="nofollow">IOC country code</a> </li> 
         </ul> 
        </div> </td> 
      </tr> 
      <tr style="height:2px"> 
       <td colspan="2">&nbsp;</td> 
      </tr> 
      <tr> 
       <th>Geodesic place codes</th> 
       <td style="padding:0px; width:100%; text-align:left; border-left-width:2px; border-left-style:solid"> 
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              Global 
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           <td style="padding:0px; width:100%; text-align:left; border-left-width:2px; border-left-style:solid"> 
            <div style="padding:0em 0.25em"> 
             <ul> 
              <li><strong>Geohash</strong> </li> 
              <li><a title="Geohash-36" href="http://en.wikipedia.org/wiki/Geohash-36" rel="nofollow">Geohash-36</a> </li> 
              <li><a title="Georef" href="http://en.wikipedia.org/wiki/Georef" rel="nofollow">Georef</a> </li> 
              <li><a title="Geotude (page does not exist)" href="http://en.wikipedia.org/w/index.php?title=Geotude&amp;action=edit&amp;redlink=1" rel="nofollow">Geotude</a> </li> 
              <li><a title="SALB (page does not exist)" href="http://en.wikipedia.org/w/index.php?title=SALB&amp;action=edit&amp;redlink=1" rel="nofollow">SALB</a> </li> 
              <li><a title="Marsden square" href="http://en.wikipedia.org/wiki/Marsden_square" rel="nofollow">Marsden square</a> </li> 
              <li><a title="Natural Area Code" href="http://en.wikipedia.org/wiki/Natural_Area_Code" rel="nofollow">Natural Area Code</a> </li> 
              <li><a title="QDGC" href="http://en.wikipedia.org/wiki/QDGC" rel="nofollow">QDGC</a> </li> 
              <li><a title="UN/LOCODE" href="http://en.wikipedia.org/wiki/UN/LOCODE" rel="nofollow">UN/LOCODE</a> </li> 
              <li><a title="Universal Transverse Mercator coordinate system" href="http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system" rel="nofollow">UTM</a> </li> 
              <li><a title="World Meteorological Organization squares" href="http://en.wikipedia.org/wiki/World_Meteorological_Organization_squares" rel="nofollow">WMO squares</a> </li> 
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             <a title="North America" href="http://en.wikipedia.org/wiki/North_America" rel="nofollow">North America</a> 
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             <ul> 
              <li><a title="List of FIPS country codes" href="http://en.wikipedia.org/wiki/List_of_FIPS_country_codes" rel="nofollow">FIPS country code</a> (FIPS 10-4) </li> 
              <li><a title="FIPS place code" href="http://en.wikipedia.org/wiki/FIPS_place_code" rel="nofollow">FIPS place code</a> (FIPS 55) </li> 
              <li><a title="FIPS county code" href="http://en.wikipedia.org/wiki/FIPS_county_code" rel="nofollow">FIPS county code</a> (FIPS 6-4) </li> 
              <li><a title="Federal Information Processing Standard state code" href="http://en.wikipedia.org/wiki/Federal_Information_Processing_Standard_state_code" rel="nofollow">FIPS state code</a> (FIPS 5-2) </li> 
              <li><a title="Standard Geographical Classification code (Canada)" href="http://en.wikipedia.org/wiki/Standard_Geographical_Classification_code_%28Canada%29" rel="nofollow">SGC codes</a> </li> 
             </ul> 
            </div> </td> 
          </tr> 
         </tbody> 
        </table> </td> 
      </tr> 
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       <td colspan="2">&nbsp;</td> 
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       <th><a title="Postal code" href="http://en.wikipedia.org/wiki/Postal_code" rel="nofollow">Postal codes</a></th> 
       <td style="padding:0px; width:100%; text-align:left; border-left-width:2px; border-left-style:solid"> 
        <div style="padding:0em 0.25em"> 
         <ul> 
          <li><a title="Natural Area Code" href="http://en.wikipedia.org/wiki/Natural_Area_Code" rel="nofollow">Natural Area Code</a> </li> 
          <li><a title="Postal Index Number" href="http://en.wikipedia.org/wiki/Postal_Index_Number" rel="nofollow">Postal Index Number</a> </li> 
          <li><a title="ZIP code" href="http://en.wikipedia.org/wiki/ZIP_code" rel="nofollow">ZIP code</a> </li> 
         </ul> 
        </div> </td> 
      </tr> 
      <tr style="height:2px"> 
       <td colspan="2">&nbsp;</td> 
      </tr> 
      <tr> 
       <th>Telephony</th> 
       <td style="padding:0px; width:100%; text-align:left; border-left-width:2px; border-left-style:solid"> 
        <div style="padding:0em 0.25em"> 
         <ul> 
          <li><a title="List of ITU letter codes" href="http://en.wikipedia.org/wiki/List_of_ITU_letter_codes" rel="nofollow">ITU-R country codes</a> </li> 
          <li><a title="List of country calling codes" href="http://en.wikipedia.org/wiki/List_of_country_calling_codes" rel="nofollow">ITU-T country calling codes</a> </li> 
          <li><a title="Mobile country code" href="http://en.wikipedia.org/wiki/Mobile_country_code" rel="nofollow">ITU-T mobile calling codes</a> </li> 
         </ul> 
        </div> </td> 
      </tr> 
      <tr style="height:2px"> 
       <td colspan="2">&nbsp;</td> 
      </tr> 
      <tr> 
       <th>Radio broadcasting</th> 
       <td style="padding:0px; width:100%; text-align:left; border-left-width:2px; border-left-style:solid"> 
        <div style="padding:0em 0.25em"> 
         <ul> 
          <li><a title="Maidenhead Locator System" href="http://en.wikipedia.org/wiki/Maidenhead_Locator_System" rel="nofollow">Maidenhead Locator System</a> </li> 
          <li>Historical&nbsp;: <a title="QRA locator" href="http://en.wikipedia.org/wiki/QRA_locator" rel="nofollow"> QRA locator</a> </li> 
         </ul> 
        </div> </td> 
      </tr> 
      <tr style="height:2px"> 
       <td colspan="2">&nbsp;</td> 
      </tr> 
      <tr> 
       <th>Sport</th> 
       <td style="padding:0px; width:100%; text-align:left; border-left-width:2px; border-left-style:solid"> 
        <div style="padding:0em 0.25em"> 
         <ul> 
          <li><a title="List of IOC country codes" href="http://en.wikipedia.org/wiki/List_of_IOC_country_codes" rel="nofollow">IOC country codes</a> </li> 
         </ul> 
        </div> </td> 
      </tr> 
     </tbody> 
    </table> </td> 
  </tr> 
 </tbody> 
</table>

Retrieved from " [http://en.wikipedia.org/w/index.php?title=Geohash&oldid=651848024][http_en.wikipedia.org_w_index.php_title_Geohash_oldid_651848024]"

[Categories][]:

*  [Geocodes][]

[navigation]: http://en.wikipedia.org/wiki/Geohash#mw-head
[search]: http://en.wikipedia.org/wiki/Geohash#p-search
[Geohashing]: http://en.wikipedia.org/wiki/Geohashing
[latitude]: http://en.wikipedia.org/wiki/Latitude
[longitude]: http://en.wikipedia.org/wiki/Longitude
[geocode]: http://en.wikipedia.org/wiki/Geocoding
[Gustavo Niemeyer]: http://en.wikipedia.org/w/index.php?title=Gustavo_Niemeyer&action=edit&redlink=1
[geohash.org]: http://geohash.org/
[grid]: http://en.wikipedia.org/wiki/Grid_%28spatial_index%29
[hide]: http://en.wikipedia.org/wiki/Geohash#
[1 Service]: http://en.wikipedia.org/wiki/Geohash#Service
[2 Uses]: http://en.wikipedia.org/wiki/Geohash#Uses
[3 Example]: http://en.wikipedia.org/wiki/Geohash#Example
[3.1 Decode from base 32]: http://en.wikipedia.org/wiki/Geohash#Decode_from_base_32
[3.2 Decode binary to decimal]: http://en.wikipedia.org/wiki/Geohash#Decode_binary_to_decimal
[3.3 Worked example]: http://en.wikipedia.org/wiki/Geohash#Worked_example
[4 Limitations]: http://en.wikipedia.org/wiki/Geohash#Limitations
[5 License and patents]: http://en.wikipedia.org/wiki/Geohash#License_and_patents
[6 See also]: http://en.wikipedia.org/wiki/Geohash#See_also
[7 External links]: http://en.wikipedia.org/wiki/Geohash#External_links
[8 References]: http://en.wikipedia.org/wiki/Geohash#References
[edit]: http://en.wikipedia.org/w/index.php?title=Geohash&action=edit&section=1
[URLs]: http://en.wikipedia.org/wiki/Uniform_Resource_Locator
[Earth]: http://en.wikipedia.org/wiki/Earth
[emails]: http://en.wikipedia.org/wiki/Email
[forums]: http://en.wikipedia.org/wiki/Internet_forum
[websites]: http://en.wikipedia.org/wiki/Website
[GPX]: http://en.wikipedia.org/wiki/GPX_%28data_transfer%29
[GPS]: http://en.wikipedia.org/wiki/GPS
[peninsula]: http://en.wikipedia.org/wiki/Peninsula
[Jutland]: http://en.wikipedia.org/wiki/Jutland
[Denmark]: http://en.wikipedia.org/wiki/Denmark
[http_geohash.org_u4pruydqqvj]: http://geohash.org/u4pruydqqvj
[edit 1]: http://en.wikipedia.org/w/index.php?title=Geohash&action=edit&section=2
[geotagging]: http://en.wikipedia.org/wiki/Geotagging
[GeoZip]: http://geozipcode.blogspot.com/2015/02/geozip.html
[edit 2]: http://en.wikipedia.org/w/index.php?title=Geohash&action=edit&section=3
[edit 3]: http://en.wikipedia.org/w/index.php?title=Geohash&action=edit&section=4
[base 32]: http://en.wikipedia.org/wiki/Base32
[bits]: http://en.wikipedia.org/wiki/Bit
[edit 4]: http://en.wikipedia.org/w/index.php?title=Geohash&action=edit&section=5
[edit 5]: http://en.wikipedia.org/w/index.php?title=Geohash&action=edit&section=6
[min _le _mathrm_round_value_ _le _max]: /images/20220805/c696f313a06f4f7181635f85c0686ff8.png
[edit 6]: http://en.wikipedia.org/w/index.php?title=Geohash&action=edit&section=7
[Edge case]: http://en.wikipedia.org/wiki/Edge_case
[Z-order curve]: http://en.wikipedia.org/wiki/Z-order_curve
[_1]: http://lucenerevolution.org/sites/default/files/Lucene%20Rev%20Preso%20Smiley%20Spatial%20Search.pdf
[coordinates of longitude and latitude]: http://en.wikipedia.org/wiki/Geographical_coordinate_system
[Haversine formula]: http://en.wikipedia.org/wiki/Haversine_formula
[Map projection]: http://en.wikipedia.org/wiki/Map_projection
[Hilbert curve]: http://en.wikipedia.org/wiki/Hilbert_curve
[cartesian coordinate system]: http://en.wikipedia.org/wiki/Cartesian_coordinate_system
[1]: http://en.wikipedia.org/wiki/Geohash#cite_note-1
[2]: http://en.wikipedia.org/wiki/Geohash#cite_note-2
[Accumulo]: http://en.wikipedia.org/wiki/Accumulo
[3]: http://en.wikipedia.org/wiki/Geohash#cite_note-3
[Locational codes]: http://www.cs.umd.edu/~hjs/pubs/SametVisualComputer89.pdf
[4]: http://en.wikipedia.org/wiki/Geohash#cite_note-4
[5]: http://en.wikipedia.org/wiki/Geohash#cite_note-5
[edit 7]: http://en.wikipedia.org/w/index.php?title=Geohash&action=edit&section=8
[public domain]: http://en.wikipedia.org/wiki/Public_domain
[6]: http://en.wikipedia.org/wiki/Geohash#cite_note-6
[7]: http://en.wikipedia.org/wiki/Geohash#cite_note-7
[8]: http://en.wikipedia.org/wiki/Geohash#cite_note-8
[9]: http://en.wikipedia.org/wiki/Geohash#cite_note-9
[edit 8]: http://en.wikipedia.org/w/index.php?title=Geohash&action=edit&section=9
[Geohash-36]: http://en.wikipedia.org/wiki/Geohash-36
[Morton number _number theory]: http://en.wikipedia.org/wiki/Morton_number_%28number_theory%29
[Natural Area Code]: http://en.wikipedia.org/wiki/Natural_Area_Code
[Maidenhead Locator System]: http://en.wikipedia.org/wiki/Maidenhead_Locator_System
[Military grid reference system]: http://en.wikipedia.org/wiki/Military_grid_reference_system
[edit 9]: http://en.wikipedia.org/w/index.php?title=Geohash&action=edit&section=10
[elasticsearch_ the definitive guide - Geo]: http://www.elasticsearch.org/guide/en/elasticsearch/guide/current/geoloc.html
[Visualizing Geohash]: http://www.bigdatamodeling.org/2013/01/intuitive-geohash.html
[Perl module to interact with geohash.org]: https://metacpan.org/module/Net::Geohash
[in C]: https://github.com/lyokato/libgeohash
[Python]: https://pypi.python.org/pypi/Geohash/
[Haskell]: https://github.com/mariusaeriksen/geohash
[Perl]: https://metacpan.org/module/Geo::Hash
[Ruby _Gem]: http://geohash.rubyforge.org/
[Ruby]: https://github.com/paulasmuth/redis_geohash/blob/master/lib/redis_geohash/geohash.rb
[Ocaml]: http://code.google.com/p/ocaml-geohash/
[Clojure]: https://clojars.org/geohash
[Go]: https://github.com/the42/cartconvert/tree/master/cartconvert
[Objective-C]: https://github.com/lyokato/objc-geohash
[Javascript]: https://github.com/davetroy/geohash-js/
[Demo]: http://openlocation.org/geohash/geohash-js/
[PHP]: http://blog.dixo.net/downloads/geohash-php-class/
[MySQL]: https://github.com/nowelium/geohash-mysql-func
[PostGIS]: http://www.postgis.org/docs/ST_GeoHash.html
[nodejs]: https://github.com/sunng87/node-geohash
[geospatialweb]: http://code.google.com/p/geospatialweb/source/browse/#svn/trunk/geohash/src
[jgeohash]: http://astrapi69.github.io/jgeohash/
[geohash-java]: https://github.com/kungfoo/geohash-java
[geo]: https://github.com/davidmoten/geo
[kml file for Google Earth displaying geohash grid]: http://api.prezzibenzina.it/geohash.kml
[Area Check Tool]: http://geohash.2ch.to/
[2 1]: http://www.geomesa.org/
[GeoMesa]: http://en.wikipedia.org/wiki/GeoMesa
[Simple and fast conversion from geohash to latitude_longitude and from latitude_longitude to geohash]: http://geohash.co/
[edit 10]: http://en.wikipedia.org/w/index.php?title=Geohash&action=edit&section=11
[Jump up]: http://en.wikipedia.org/wiki/Geohash#cite_ref-1
[geo_shape Type Mapping in Elasticsearch]: http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/mapping-geo-shape-type.html
[Jump up 1]: http://en.wikipedia.org/wiki/Geohash#cite_ref-2
[Geospatial Indexing in MongoDB]: http://www.mongodb.org/display/DOCS/Geospatial+Indexing
[Jump up 2]: http://en.wikipedia.org/wiki/Geohash#cite_ref-3
[Spatio-temporal Indexing in Non-relational Distributed Databases]: http://geomesa.github.io/assets/outreach/SpatioTemporalIndexing_IEEEcopyright.pdf
[Jump up 3]: http://en.wikipedia.org/wiki/Geohash#cite_ref-4
[Spatial Keys]: http://karussell.wordpress.com/2012/05/23/spatial-keys-memory-efficient-geohashes/
[Jump up 4]: http://en.wikipedia.org/wiki/Geohash#cite_ref-5
[QuadTiles]: http://wiki.openstreetmap.org/wiki/QuadTiles
[Jump up 5]: http://en.wikipedia.org/wiki/Geohash#cite_ref-6
[geohash.org announcement post in groundspeak.com forum]: http://forums.groundspeak.com/GC/index.php?showtopic=186412
[Jump up 6]: http://en.wikipedia.org/wiki/Geohash#cite_ref-7
[Compact text encoding of latitude_longitude coordinates - Patent 20050023524]: http://www.freepatentsonline.com/20050023524.html
[Jump up 7]: http://en.wikipedia.org/wiki/Geohash#cite_ref-8
[Does Microsoft Infringe the Natural Area Coding System]: http://www.gps-practice-and-fun.com/nacgeo.html#Microsoft
[Jump up 8]: http://en.wikipedia.org/wiki/Geohash#cite_ref-9
[The Natural Area Coding System - Legal and Licensing]: http://www.nacgeo.com/nacsite/licensing/
[http_en.wikipedia.org_w_index.php_title_Geohash_oldid_651848024]: http://en.wikipedia.org/w/index.php?title=Geohash&oldid=651848024
[Categories]: http://en.wikipedia.org/wiki/Help:Category
[Geocodes]: http://en.wikipedia.org/wiki/Category:Geocodes