| I'm pretty certain one could make a geohash compatible partly human readable hybrid that performs way better than this proprietary obscurity. Something like DE.BERLIN.2.1H First, human readable part defines a look-up to defined geohash of center of region on a given level. So DE.BERLIN could resolve to u33, u33d or u33db (length/level 5)
the last one seems reasonable, since a few multiples of the area cover the whole city of Berlin http://geohash.2ch.to/u33db Second, optional, part encodes offset of Z-Curve index of location at same zoom level. Z-Curve on globe: http://www.bigdatamodeling.org/2013/01/intuitive-geohash.htm... This enables global coverage at any level if needed, and makes the code robust to administrative changes that affect the area of the given region!
The offset part could start at 1 and alternate the sign with each increment. isOdd(offsetPart) ? -(offsetPart-1)/2 : offsetPart/2; 1 → 0, 2 → 1, 3 → -1, 4 → 2 An offset part of 1 equals an offset of 0 and could be omitted. The third part adds to the precision of that given cell. Brandenburg Gate, within area of origin cell of region part.
could be written as DE.BERLIN.1.2M3 or short DE.BERLIN.2M3 http://geohash.2ch.to/u33db2m3 DE.Berlin.2.1H would be the area and center point of the Berliner Fernsehturm with sufficient accuracy
u33db + 1 = u33dc http://geohash.2ch.to/u33dc1h This example uses base 32 to comply with geohash but other more error robust encodings and variations (e.g. second part as base ten numerals) could be used as well. Add optional checksum part based on unshortened geohash if needed to verify integrity. Variants: since geohash, covers a varying amount of area depending on the latitude. A similiar approach could be realized on a UTM based grid like MGRS if a precise area is required (https://en.wikipedia.org/wiki/MGRS) |