query-geo-boundary

QueryGeoBoundary

A Node.js library to query the geo (administrative area) boundary from OSM nominatim and/or overpass.

Usage

const queryGeoBoundary = require('query-geo-boundary');
queryGeoBoundary(`${geo_name}`).then(boundaries => {
  // your post-processing here
}).catch(err => {
  // your error handling here
});

API

Prototype: queryGeoBoundary(geoName, options)

• geoName: name of the geo you want to obtain its boundary
• options: optional. only support source option right now, you can use {source: 'overpass'} to mandata it to go through overpass service (very slow, and has concurrency limitation), by default (and highly-recommended) it will use openstreetmap nominatim service.

Return: an array of osm places with boundary geojson (the place attributes include displayname, lat/lon, boundingbox, and the boundary geojson under "geojson"). A typical result is as below:

  [{"place_id":"158973269",
  "licence":"Data © OpenStreetMap contributors, ODbL 1.0. http://www.openstreetmap.org/copyright",
  "osm_type":"relation",
  "osm_id":"3468769",
  "boundingbox":["35.7163774","36.2834811","118.9952393","119.7232973"],"lat":"35.9989034","lon":"119.342173467495",
  "display_name":"诸城市, 潍坊市, 山东省, 中国",
  "class":"boundary",
  "type":"administrative",
  "importance":0.43599614036271,
  "icon":"https://nominatim.openstreetmap.org/images/mapicons/poi_boundary_administrative.p.20.png",
  "geojson":{"type":"Polygon","coordinates":[[[118.9952393,36.0120809],...,[118.9952393,36.0120809]]]}}]

Notice: 'coz it's very common for an administrative uint has the same name with the others, if you want to get the boundary of exactly that place, please supply as much as possible hierarchical adminstrative information in name, e.g., using "Ikeda, Hokkaido" rather than "Ikeda", or you can solve this kind of ambiguity by introducing human interference.

Node.JS Requirement

• Node.JS 4.x+ with ES6 features supports

Dependency

• request - basic version and basic function (can be easily replaced by built-in http module)
• osm2geojson-lite - a regex and map accelerated xml parsing & geojson reconstruction utility, much faster than xmldom, osmtogeojson in combination to convert an OSM XML to geojson