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Questions tagged [geohash]

Geohashes are a way of encoding latitude/longitude points as strings. Geohashes are a hierarchical spatial data structure which subdivides space into buckets of grid shape

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34 views

How to delete geohash rectangles from Leaflet?

I have been inspired by this code to create a geohash map for my Neo4j geohash graph on Leaflet: Unlike the (lat/lon) markers, the geohash string is represented as a rectangle in the map. For a ...
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71 views

Geohash length to be reversible to LatLong using PostGIS

Decode/encode Geohashes are easy, and there are a "rule of the thumb" for estimat mininal Geohashe length for each LatLong precision. The question is other: precision for revesibility, How many ...
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1answer
190 views

Server side clustering with geohash

I need help with clustering algorithm. I have a mysql database with lat, lng, geohash(12 chars). I am usign this query to select all records for zoom level 2 (2 chars) SELECT COUNT( id ) , LEFT( `...
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31 views

Why quadkeys are formed by interleaving

I am new to GIS and i was reading about quadkeys and Geohashes. I see both are formed by interleaving. While quadkeys are formed by interleaving the X,Y coordinates, GeoHashes are formed by ...
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226 views

Generating a single geohash for a bounding box in python

the following code generates bounding box for the coordinates that are given in the input but currently it generates geohashes for all the 4 coordinates of the polygon. i want to be able to generate a ...
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0answers
107 views

Geo-hash finding nearest neighbour with massively variable distance to actual nearest neighbour

I have a series of points in lat-long space, ranging from having their nearest neighbour very close to 1000s of km away. Say I do a geo-hash of these to a high precision, my search of nearest ...
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119 views

Geohash Clustring on Leaflet

Leaflet has a markerclustring plugin that cluster markers. i am asking is there a solution to cluster your(lat/lon) with geohash on leaflet map as it is possible on Kibana ?
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1answer
377 views

Convert geohash to shape/kml

I have a requirement where I need to convert a set of Geohash to KML files such that they can be used as areas to plot data by overlaying on map. Is anyone aware of an open resource which can help ...
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176 views

How to take a set of geohashes and determine which ones are neighbors?

I'm trying to figure out the optimal way to take a list of geohashes and return a sub-list that contains the geohashes that are direct neighbors or have direct neighbors in common (aka - creating ...
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36 views

Pyqgis script to join delimited text layer on KML and create graduated symbols

I need to create multiple maps from QGIS which have the same procedure and so wanted to write a script. I found little help in terms of how to join delimited text layer to a KML vector layer(of ...
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1answer
982 views

How to decide geohash length based on zoom level?

I want to decide geohash length based on zoom level, how can I do that because so far I am unable to find any standard way to do so? For example, current zoom level is 10 and geohash is "...
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355 views

Geohash to polygon [closed]

Is there a way (in python or postgis) to create polygon geometries from geohashes? It is my understanding that geohashes are created from point data (lat, lon). Would it be logical to create a ...
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283 views

Geohash using decimal

I'm quite new to spatial data processing and got to work with some existing legacy data which isnt well documented. I see that in the SQL database geohash values stored along with lat and lon but they ...
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1answer
731 views

Understanding the s2 library (geometry on the sphere, cells and Hilbert curve) for finding points nearby

I am having trouble understanding how the S2 library works so things in this question may make no sense, but I have a goal I would like to accomplish. Lets say I have many lat/lng point I want to ...
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1answer
2k views

Calculating Optimal Geohash Precision from Bounding Box

I'm using Elasticsearch's GeoHash grid Aggregation to plot clusters on a map (using Leaflet). I understand that for larger areas a lower precision setting should be used to limit the number of buckets ...
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1answer
453 views

Converting files to S2 cell IDs

I would like to use Google's S2 library to convert geospatial data (for instance shapefiles or geojson files) to S2 cell IDs. The data I want to convert is made of polygons. I saw there exists this ...
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1answer
478 views

Using PostGIS Geohash function to run through column of coordinates and dump results in new column?

I'm new to databases. How can I use the PostGIS Geohash function to run through a column of coordinates and dump results in new column? Here is the postgis documentation on it Here's what my data ...
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255 views

Efficiency differences between quadtree and geohashes [closed]

I am a newbie to spatial indexing. Can someone please explain me the differences between a quad-tree and geohash. From what I understand both use similar hierarchial methods of dividing the space into ...
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3answers
2k views

Library to convert polygon to geohash

There are plenty of Python libraries that convert Point to geohash. I need to convert an area, enclosed in Polygon to do that. I can't just go around the perimeter points, I'll have a hole inside. ...
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87 views

Hash function to generate grid cell Id

I'm new to GIS and I have 'part of' a problem to solve. Basically I have road details in geojson (WGS84) with LineString of points covering a 100KM square. I'm designing an architecture to snap a ...
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0answers
288 views

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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1answer
2k 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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1answer
575 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
5k 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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0answers
668 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
3k 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
10k 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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1answer
20k 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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1answer
4k 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
780 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 ...
6
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1answer
1k 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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3answers
5k views

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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2answers
2k 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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1answer
239 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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0answers
2k 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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5answers
26k views

Using 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 ...