Work on osm boundaries
Added code to merge multiple polygons representing a single boundary
into single multipolygon
diff --git a/index.js b/index.js
index 6d6196e..43ba4d1 100644
--- a/index.js
+++ b/index.js
@@ -2,10 +2,16 @@
http = require('http')
var async = require('async'),
+ jsts = require('jsts'),
overpass = require('query-overpass'),
shp = require('shpjs')
+var osmBoundarySources = require('./osmBoundarySources.json'),
+ geoJsonReader = new jsts.io.GeoJSONReader(),
+ geoJsonWriter = new jsts.io.GeoJSONWriter()
+
+
var toArrayBuffer = function(buffer) {
var ab = new ArrayBuffer(buffer.length)
var view = new Uint8Array(ab)
@@ -21,7 +27,72 @@
.catch(function(e){ console.log('extract err', e); callback(e) })
}
-var osmBoundarySources = require('./osmBoundarySources.json')
+var union = function(a, b) {
+ var _a = geoJsonReader.read(JSON.stringify(a)),
+ _b = geoJsonReader.read(JSON.stringify(b))
+
+ var result = _a.union(_b)
+
+ return geoJsonWriter.write(result)
+
+}
+
+var downloadOsmBoundary = function(boundaryId, boundaryCallback) {
+ var cfg = osmBoundarySources[boundaryId],
+ query = '[out:json][timeout:60];',
+ boundaryFilename = './downloads/' + cfg.type,
+ debug = 'getting data for '
+
+ if(cfg.type === 'ISO3166-1') {
+ query += '(relation["boundary"="administrative"]' +
+ '["admin_level"="2"]' +
+ '["ISO3166-1"="' + cfg.code + '"]);' +
+ 'out body;>;out meta qt;'
+ boundaryFilename += '_' + cfg.code
+ debug += 'country: ' + cfg.code
+ }
+
+ console.log(debug)
+
+ async.auto({
+ checkForAlreadyDownloadedFile: function(cb) {
+ fs.stat(boundaryFilename, function(err) {
+ if(!err) { return boundaryCallback() }
+ cb()
+ })
+ },
+ downloadFromOverpass: ['checkForAlreadyDownloadedFile', function(results, cb) {
+ console.log('downloading from overpass')
+ overpass(query, cb, { flatProperties: true })
+ }],
+ validateOverpassResult: ['downloadFromOverpass', function(results, cb) {
+ var data = results.downloadFromOverpass
+ if(!data.features || data.features.length == 0) {
+ err = new Error('Invalid geojson for boundary: ' + boundaryId)
+ return cb(err)
+ }
+ cb()
+ }],
+ saveSingleMultiPolygon: ['validateOverpassResult', function(results, cb) {
+ var data = results.downloadFromOverpass,
+ combined
+
+ // union all multi-polygons / polygons into one
+ for (var i = data.features.length - 1; i >= 0; i--) {
+ var curGeom = data.features[i].geometry
+ if(curGeom.type === 'Polygon' || curGeom.type === 'MultiPolygon') {
+ console.log('combining border')
+ if(!combined) {
+ combined = curGeom
+ } else {
+ combined = union(curGeom, combined)
+ }
+ }
+ }
+ fs.writeFile(boundaryFilename, JSON.stringify(combined, null, 2), cb)
+ }]
+ }, boundaryCallback)
+}
async.auto({
makeDownloadsDir: function(cb) {
@@ -47,27 +118,14 @@
.on('error', cb)
})
}],
- extractShapefile: ['getEfeleShapefile', function(results, cb) {
- console.log('extracting efele.net shapefile')
- extractToGeoJson(cb)
- }],
getOsmBoundaries: ['makeDownloadsDir', function(results, cb) {
console.log('downloading osm boundaries')
- var boundaryIds = Object.keys(osmBoundarySources)
- async.eachSeries(boundaryIds,
- function(boundaryId, boundaryCallback) {
- var cfg = osmBoundarySources[boundaryId]
- console.log('osm boundary for:', boundaryId, cfg.query)
- overpass(cfg.query, function(err, data) {
- if(err) { return boundaryCallback(err) }
- if(!data.features || data.features.length == 0) {
- err = new Error('Invalid geojson for boundary: ' + boundaryId)
- return boundaryCallback(err)
- }
- // union all multi-polygons / polygons into one
- fs.writeFile('./downloads/' + boundaryId, JSON.stringify(data, null, 2), boundaryCallback)
- }, { flatProperties: true })
- }, cb)
+ async.eachSeries(Object.keys(osmBoundarySources), downloadOsmBoundary, cb)
+ }],
+ extractEfeleNetShapefile: ['getOsmBoundaries', function(results, cb) {
+ return cb()
+ console.log('extracting efele.net shapefile')
+ extractToGeoJson(cb)
}]
}, function(err) {
console.log('done')