ohsome2X

Query OSM History Data (count, length, area) about specific OSM Features or OSM User activity (user-count) for your areas of interest.

Input: Accepts GeoJSON or PostgreSQL/PostGIS as input source.

Output: Creates a GeoJSON File or new result table in your PostgreSQL/PostGIS database.

The package includes a library with a single class to run.

Additionally it includes ohsome2x-cli, a command-line tool with a configuration wizard to create and run a query-configuration-JSON.

This library/tool makes use of the ohsome API (https://api.ohsome.org) as data backend and many other great open-source libraries.

Currently supported ohsome API query types are:

//standard
elements/count/groupBy/boundary
elements/length/groupBy/boundary
elements/area/groupBy/boundary
elements/perimeter/groupBy/boundary

//ratio 
elements/count/ratio/groupBy/boundary
elements/length/ratio/groupBy/boundary
elements/area/ratio/groupBy/boundary
elements/perimeter/ratio/groupBy/boundary

//group by tags within each boundary
elements/count/groupBy/boundary/groupBy/tag
elements/length/groupBy/boundary/groupBy/tag
elements/area/groupBy/boundary/groupBy/tag
elements/perimeter/groupBy/boundary/groupBy/tag

//contributors
users/count/groupBy/boundary

This software is developed by HeiGIT:

Usage

There are two ways how you can use ohsome2x.

1. Without installation using the npm package runner npx

Info: The npx command comes with the installation of npm.

To run the command-line wizard:

Syntax info:
$ npx @giscience/ohsome2x
-------------------------
USAGE:
with 'npx'
npx @giscience/ohsome2x createconfig [(-o|--out) path]
npx @giscience/ohsome2x run (-c|--conf) fullConfig.json
as local command
node ohsome2x-cli.js createconfig [(-o|--out) path]
node ohsome2x-cli.js run (-c|--conf) fullConfig.json
-------------------------

2. With installation as library to use it in your Node.js script

1. For use as library in Node.js install the package:

   $ npm install @giscience/ohsome2x

2. You find the built library in the /dist folder after executing:

   $ npm run build

3. Write your own JavaScript or TypeScript file:

   See Examples and API section to learn how to do it. Enjoy!

Example

Query the number of buildings in a bbox around Heidelberg in a yearly resolution from 2008 to 2020

Step 1. You need some input (one or many polygons): heidelberg.geojson

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {"id": "Heidelberg"},
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [ [8.625984191894531, 49.38527827629032],
            [8.735504150390625, 49.38527827629032],
            [8.735504150390625, 49.433975502014675],
            [8.625984191894531, 49.433975502014675],
            [8.625984191894531, 49.38527827629032]
          ]]}}]}

Step 2. Specify your query as JSON-file (you can use the commandline wizard to create this): myquery.json

Info: for the filter Syntax see: https://docs.ohsome.org/ohsome-api/stable/filter.html

{
  "ohsomeQuery": {
    "queryType": "elements/count/groupBy/boundary",
    "filter": "building=* and building!=no and geometry:polygon",
    "time": "2008/2020/P1Y"
  },
  "source": {
    "geometryId": "id",
    "name": "heidelberg.geojson",
    "store": { "path": "heidelberg.geojson", "type": "geojson" }
  },
  "target": {
    "horizontalTimestampColumns": false,
    "createGeometry": true,
    "transformToWebmercator": false,
    "storeZeroValues": true,
    "computeValuePerArea": true,
    "name": "heidelberg_buildings_count.geojson",
    "store": { "path": "heidelberg_buildings_count.geojson", "type": "geojson" }
  }
}

Step 3. Run the Query

$ npx @giscience/ohsome2x run --conf myquery.json

API

Basic Usage

Node:

const Ohsome2X = require('@giscience/ohsome2x');

// you can create this config using the command-line wizard, run: npx ohsome2x-cli
const config = {
                ohsomeQuery: {...},
                source: {...},
                target: {...}
}                               

const ohsome2x = new Ohsome2X(config);

// This will return a Promise
ohsome2x.run().catch(console.log);

TypeScript:

import Ohsome2X = require('@giscience/ohsome2x'); 
import {Ohsome2XConfig} from '@giscience/ohsome2x/dist/config_types_interfaces';

// you can create this config using the command-line wizard, run: npx ohsome2x-cli
const config: Ohsome2XConfig = {
                ohsomeQuery: {...},
                source: {...},
                target: {...}
}                               

const ohsome2x = new Ohsome2X(config);

// This will return a Promise
ohsome2x.run().catch(console.log);

Events

The Ohsome2X object currently provides 2 event types that can be listened to:

• progress for getting progress updates. Especially useful for iterative processing of large input datasets

  progress provides the following object to your callback (use processed and total to compute a progress percentage):

  {
      "type":      "progress",                
      "processed": <number> of already finished input geometries, 
      "total":     <number> of all input geometries,
      "cursor":    <number> that indicates the current state of iterative processing in case you configured source and target as PostGIS-Stores and specified a fetchSize,
      "fetchSize": <number> fetchSize that is currently used to fetch the next chunk of source data,
      "timestamp": <string> ISO timestamp 
  }

• finished to get some information on duration and finishing time:

  {
      "type":         "finished", 
      "duration":     <string> a human readable duration like '2 days 13 hours 45 min 12 seconds', 
      "duration_ms":  <number> duration in milliseconds, 
      "timestamp":    <string> ISO timestamp
  }

Example:

const Ohsome2X = require('@giscience/ohsome2x');

// you can create this config using the command-line wizard, run: npx ohsome2x-cli
const config = {
              ohsomeQuery: {
                  "queryType": "users/count/groupBy/boundary",
                  "filter": "natural=tree and type:node",
                  "time": "2010/2020/P1Y"
              },
              source: {
                   "schema": "public",
                   "name": "my_source_table_name",
                   "geometryId": "id", // name of the id column. Can be numbers or strings.
                   "geometryColumn": "geom",
                   "fetchSize": 5000, // this option triggers an iterative processing 
                   "cursor": null, // can be used to resume an interrupted iterative processing at a certain position. Get this information from the 'fetch' event.
                   "store": {
                       "host": "your.postgis.server.com",
                       "port": "5434",
                       "database": "your_database_name",
                       "user": "username",
                       "password": "secret",
                       "type": "postgis"
                   }
              },
              target: {...another PostGIS target config...}
}                               

const ohsome2x = new Ohsome2X(config);

// define functions to be executed when an event is reported
ohsome2x.on('progress', (evt)=>console.log(evt, ((evt.processed / evt.total) * 100).toFixed(0) +'%'));
ohsome2x.on('finished', (evt)=>console.log(evt.duration));

// This will return a Promise
ohsome2x.run().catch(console.log);

Related

• OhsomeHeX - The OSM History Explorer: Uses this library as backend
• ohsome API - WebAPI to query OSM History Data
• OSHDB - The OpenStreetMap History Database: Query OSM History Data with Java
• ohsome.org - Get information about all these technologies and more
• heigit.org - The Heidelberg Institute for Geoinformation Technology: The non-profit company behind all those useful tools.