Offline Geocoder

Node library for reverse geocoding. Designed to be used offline (for example embedded in a desktop or mobile application) - no web requests are made to perform a lookup.

Data

This uses data from the GeoNames project, which is free to use under the Creative Commons Attribution 3.0 license. To enable this to work offline, the data is imported into a SQLite database which is roughly 12 MB, so easily embeddable within an application.

By default it uses the cities1000 dataset which contains details of all worldwide cities with a population of at least 1000 people. Depending on your needs you may get better performance or accuracy by using one of their other datasets.

The GeoNames data is limited to city-level granularity, so if you need street level accuracy this won't work for you. Also most data is only available in English. Take a look at the OpenStreetMap Nominatim project for a similar tool with a lot more features.

The advantages of this working offline are you don't need to pay or obtain a license key, and it's fast. On my meager laptop I can perform around 300 lookups per second with a single process.

Installation

npm install --save offline-geocoder

You also need to obtain a database which isn't included in the package, to generate your own take a look in scripts.

Usage

When you initialize the library you need to pass the location of the database:

const geocoder = require('offline-geocoder')({ database: 'data/geodata.db' })

Reverse Geocoding

To perform a revese geocode lookup just pass the coordinates:

geocoder.reverse(41.89, 12.49)
  .then(function(result) {
    console.log(result)
  })
  .catch(function(error) {
    console.error(error)
  })

Which outputs:

{ id: 3169070,
  name: 'Rome',
  formatted: 'Rome, Latium, Italy',
  country: { id: 'IT', name: 'Italy' },
  admin1: { id: 7, name: 'Latium' },
  coordinates: { latitude: 41.89193, longitude: 12.51133 } }

The library also has a callback interface:

geocoder.reverse(41.89, 12.49, function(error, result) {
  console.log(result)
})

License

This library is licensed under the MIT license.

You don't need to give this library attribution, but you must do so for GeoNames if you use their data!

sunrule / offline-geocoder Goto Github PK