geohash is a hashing technique optimised for combining latitude and longitude pairs.

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Optimize Postgis contour lines DB

I'd like to try to optimize a world-wide 10m contour lines (isohypses) Postgis database(from SRTM). The complete DB takes 504GB on disk, contour lines are already in epsg:3857, and simplified with ...
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119 views

How to get the geohash of a bounding box?

I am storing a large collection of 5m x 5m geohash values. I want to be able to query this collection and find all the geohash values which fall within a particular georect - which is defined by a 2 ...
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85 views

Geohash vs. Open Location Code

The target is to find all POIs within a given location on a specific zoom level. If the zoom level is high, I just want to get a number of POIs and at a certain zoom level I want to get all POIs. ...
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131 views

Understanding geohash and its associated rectangles

If I decode geohash sj8101b0858n85202hbh0j I get rectangle defined by min latitude, min longitude, max latitude, max longitude. My understanding is that if I decode first part of any hash (e.g. ...
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1answer
2k views

Google's S2 library - any alternatives? [closed]

Is there any alternative to Google's S2 geometry library? It looks it was updated 4 years back and hardly any documentation. I need a library to divide cities into zones of the area I need. S2 looks ...
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181 views

How to use Morton Order(z order curve) in range search?

How to use Morton Order in range search? From the wiki, In the paragraph "Use with one-dimensional data structures for range searching", it says: the range being queried (x = 2, ..., 3, y = 2, ...
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1answer
658 views

Generating Heat Maps with GeoHash

I have a long list of GeoHash codes for a certain geographic region. I'm using 6-character precision so for example if the area under study was Earl's Court in London, I would have a few six letter ...
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1answer
4k views

Fastest strategy for proximity searches in SQL Server 2012

This is my very first question here, so bear with me! I'm implementing a back end for a mobile app which will have to do proximity searches to find nearby POIs (points os interest). I know it's a ...
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3k views

What is the precision of a Geohash

I would like to know the precision of a geohash with a given length. If there is a 'simple' formula you can use to calculate it, that would be extra-cool. Wikipedia lists the precision up to 8 ...
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2k views

Advantages of R-trees in comparison to geohashes

Geohashes are being widely used in products like: Lucene, mongodb, etc and have become one of the most important technology of present day. Have Geohashes replaced the good old R-trees or do R-trees ...
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1answer
378 views

Algorithm to find geohashes which satisfy query condition

I have an application where I need to query geohashes by specifying the bounding rectangle. Since geohashes map 2D to 1D is there a method by which I may find the prefixes of all geohashes which ...
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311 views

What is the internal format of PostGIS?

PostGIS stores its geometry entities as long strings: SELECT ST_GeomFromText('POINT(32.0 34.0)',4326); st_geomfromtext ---------------------------------------------------- ...
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What methods exist for geohash of polygon?

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 ...
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581 views

Are there trade offs between using a geohash vs using a quadkey as a spatial index?

QuadKey Bing Maps uses a quadkey structure for their tiling scheme. Here is an overview of the concept http://msdn.microsoft.com/en-us/library/bb259689.aspx. GeoHash A geohash seems to be the more ...
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138 views

Longest common prefix of geohashed points

I currently use Geohash to index some points and retrieve information faster by providing a geohash prefix for a given point for a given distance.. For example if I get a given point at '1600 ...
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972 views

Clustering table on geohash index and geohash ordered table

I wonder if there could be a performance gain to re organize the rows in a table by Geohash and then CLUSTER this table on the Geohash index of the geometries. CREATE TEMPORARY TABLE tmptbl AS SELECT ...
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3answers
12k views

Would it be possible to use geohash for proximity searches?

I'm looking to optimize point proximity geo searches time. My input is lat,lng point and I'm searching on a precomputed set of locations to n nearest points. I don't care how much time/space the ...