GeoHash is an excellent method to code the latitude and longitude of a point into a string. It's concise, due to the use of numbers + letters, and the precision can be tuned adding characters at the end.
I'm looking for an equivalent method to code polygons, not points. I saw two ways to do it:
- geohash all polygon points, then concatenate them, and then compress the resulting string using classical text compression algorithms.
- reference all geohashes included into the polygon. It's the RecursivePrefixTree method – see http://www.opensourceconnections.com/2014/04/11/indexing-polygons-in-lucene-with-accuracy/.
I would like the code could be manipulated by humans, ie. manually copied, not only by machines as an index.
Edit: see also the discussion (in French) at http://seenthis.net/messages/269838.
Best Answer
Have a look at Georaptor. Creates a compressed set of geohashes, i.e., a combination of geohashes at different levels.