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Questions tagged [geohashing]

Geohash is a latitude/longitude encoding system using Base-32 characters.

Geohash is a latitude/longitude geocode system invented by Gustavo Niemeyer when writing the web service at geohash.org, and put into the public domain. It is a hierarchical spatial data structure which subdivides space, then interleaves the latitude and longitude information in a bitwise fashion.

Geohashes offer properties like arbitrary precision and the possibility of gradually removing characters from the end of the code to reduce its size (and gradually lose precision).

Nearby places will often (but not always) present similar prefixes. The longer a shared prefix is, the closer the two places are.

See https://en.wikipedia.org/wiki/Geohash

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Storing Geodata in Cassandra

Are there any current extensions/functionalities for Cassandra to store and query efficiently geodata, e.g., by using geohashes? What would you recommend to consider, when defining a data model for such an use case? I found the following link, but…
Matzka
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Elasticsearch geohash_grid returns 1 doc count but query returns a lot

I'm using Elasticsearch 5.1 with geohash_grid query as below: { "query": { ... "geo_bounding_box":... }, "aggs": { "lochash": { "geohash_grid": { "field": "currentShopGeo", "precision": 5 } } …
Le Huu HoangGia
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How to calculate the neighbouring grids on geohash. Algorithms required

Hi I am working with a database with an implementation of geohash So as shown above, as the zoom level goes down (6 zoom levels), more of abcd gets inserted into each grid. I have represented them as a rigid grid; however, the central point is…
forJ
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Solr faceting returning the average and the count

I'm using Solr 4.10 to apply the geohashing technique to create clusters of markers to display on a map. My documents represent locations on a map, and each document has a multivalue field with the geohashes per zoom level. The solutions is as…
Paulo Rodrigues
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geo algorithm in the Redis

I check the geo source code of Redis, and one statement I cannot understanding is double difference_longitude = asin(sin(distance) / cos(latr)); What's the asin(sin(distance) / cos(latr)) meaning? Is there any theory from the…
Jason
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How to write mappings in elsaticsearch for geopoint having lat lon and alt?

My_Json_File { "addressInfo": { "city": "Wimsheim", "postcode": "71299", "geopoint": { "lon": 48.845877, "lat": 8.821861, "alt": 0.0 } }, "_id": "ac169008-aa5b-4b09-aa9e-3bf3018f316d" } Pls give…
Shreyas Rao B
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How range-queries on geotemporal data are done without filtering?

I think I understand how (x,y) or (lat, log) can be stored to allow retrieval of all points within some spacial range when using range queries on sorted data. Geohash accomplishes this by alternating lat (odd bits) and log (even bits), this way as…
CoolCodeBro
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Finding intersection between two polygons in c++

I have 2 polygons. "Polygon 1:" is expressed as (latitude,longitude) in degrees. And another "Polygon 2:" is expressed using geohash encoded cell id -- for my specific case I have assumed precision=5. Now I want to find out whether Polygon 1 and…
Jannat Arora
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DynamoDB - Data model for geohash and frequent updates

I'm build a location based "chat" application and am using Amazon's DynamoDB to take advantage of the high throughput and automatic scaling. The application will frequently update user's location's in the database (I'm using a PHP geohash library).…
Daniel
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Geohash: How much hash length is enough

For an application that needs to store Geographical location of a person in the form of Geohash, how much hash length (in characters) would be enough? The code located here (referred in Wikipedia article on Geohash) says: #define MAX_HASH_LENGTH…
Atul
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Synchronization Issue while using Apache Storm

I am trying Apache Storm for Processing Streams of GeoHash Codes. I am using this library and Apache Storm 0.9.3. The geohash details for python can be found at enter link description here. Currently, I am facing an synchronization issue in the…
anuj pradhan
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Geohashing format

Is there any specific format for a geohash value? Can I use Geohash.encode(latitude,longitude,precision="8") in ruby script? What is the maximum value that precision attribute can take? Thanks in advance for any help.
mamatha
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Clarification on previous post , Geohashing string length and accuracy?

Hello I'm a little confused about the answer I found here. The answer says that by increasing the length of the string you can increase the accuracy, which I understand. What I don't understand is how he is getting the numbers for the accuracy that…
thad
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avoiding geocode range collisions

I am in the process of extracting location entities ('Madison Square Garden', 'San Diego Zoo', etc.) from a large table of non-uniform location. I'm trying to avoid multiple entities in my new table. I don't have reliable street addresses, but am…
pedalpete
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How to create filter with geohash under lucene

I'm developing a search engine with java lucene 4.3. I'd like to understand how can I add spatial feature. Particularly, I'd like to use geohash to start. I've studied all the online documentation. I found the following references: outdated IBM…
Michelantonio Trizio
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