Friday, November 17, 2017

Alternative coordinates systems

Geohash is a public domain geocoding system invented by Gustavo Niemeyer; it encodes a geographic location into a short string of letters and digits. It is hierarchical thus is possible to have 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.

http://geohash.org/

query example:
http://geohash.org/?q=45.37,-121.7&format=url&redirect=0


What3words is a geocoding system that encodes geographic coordinates into three dictionary words with a resolution of three metres.  For example, the torch of the Statue of Liberty is located at "toned.melt.ship".
the idea behind is that a triple of words is easier to remember than a long sequence of numbers that is the usual lat-long coordinates system.
What3words has a website, apps for iOS and Android, and an API that enables bidirectional conversion of what3words address and latitude/longitude coordinates.
The grid is two-dimensional, so the addressing scheme does not distinguish between floors in a building. The system supports 14 languages, although each language covers the world's entire land areas.

This website
https://www.geocachingtoolbox.com/index.php?lang=en&page=w3w
allows to test conversion between lat-long and w3w.

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