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From "Martin Desruisseaux (JIRA)" <j...@apache.org>
Subject [jira] [Created] (SIS-104) Use cases for n-dimensionsl geohashes
Date Mon, 10 Jun 2013 08:18:19 GMT
Martin Desruisseaux created SIS-104:
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             Summary: Use cases for n-dimensionsl geohashes
                 Key: SIS-104
                 URL: https://issues.apache.org/jira/browse/SIS-104
             Project: Spatial Information Systems
          Issue Type: Improvement
          Components: Storage
            Reporter: Martin Desruisseaux
            Priority: Minor


The {{GeoHashCoder}} implementation is currently restricted to the two-dimensional geographic
coordinates case, which is what geohashes are used in web site like http://geohash.org/. However
the algorithm would be easy to generalize to the _n_-dimensional case. The main difficulty
would be to decide what to do about the range of values.

h3. The problem
Geohashes are very sensitive to the range of allowed values. For example the _de facto_ geohash
standard uses longitude in the -180° to +180° range and latitude in the -90° to 90° range.
Any change of those ranges would produce totally different geohash codes, making them unusable
to any site/software that are not aware of the new ranges.

The range of allowed values is easy to determine for longitudes and latitudes. But it is much
more difficult to fix a "standard" range of elevation or time values. There is a risk that
different peoples would use different ranges, thus leading to lot of incompatible geohashes.

This JIRA task is for collecting use cases in order to determine if something like "de facto
standard" ranges emerge at least for some domains. We may also consider using some symbols
normally not used in geohashes for declaring which ranges are used.


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