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OpenStreetMap for GIS Pros - 2014

OpenStreetMap for GIS Pros - 2014

Workshop given in UCC, 29th Jan 2014.

Richard Cantwell

January 29, 2014

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  1. Agenda: Introduction to OpenStreetMap: The origin of OSM Project Structure

    / Management Data Licensing How OSM represents data in GIS Terms: Nodes / Ways / Relations Key / Value pairs TagInfo Contributing: GIS Based Editors Consuming: Tiles, Files and API’s: Tileservers – your own and/or others Files – Downloads, Databases & QGIS API’s – OverPass Turbo TileMill Spatialite Wider Issues: Comparing OSM and Commercial Data What now for Commercial Mapping? The future of Tiles Close: Contacting OSM 10 'Takeaways' Q & A
  2. Introduction to OpenStreetMap: OSM in 2 minutes: The origin of

    OSM How OSM is organised Data Licensing
  3. Project Structure • “Rather Light” • “Do-ocracy” / “Meritocracy” •

    Somebody has to run the servers etc.: OSM Foundation (OSMF) • Contributors are a broad church
  4. How OSM represents data in GIS Terms: Nodes / Ways

    / Relations Key / Value pairs TagInfo
  5. Geographic Information is represented as: Nodes Point Ways Line Closed

    Line Area (Polygon) eg. Roundabouts Relations Multi (Point / Line / Polygon) eg. Bus Routes / Inner Rings
  6. Contributing: Wide Range of Editors: • In Browser • In

    Desktop GIS • Mobile • Paper (!)
  7. Consuming: Tiles, Files and API’s: The OSM ‘Stack’ Tiles –

    your own and/or others Files – Downloads, Databases, QGIS API’s – OverPass Turbo TileMill – quick overview Spatialite – SQL without the overhead
  8. OpenStreetMap – Tile Usage wiki.openstreetmap.org/wiki/Tile_Disk_Usage OSM does NOT pre-render every

    tile. Pre-rendering all tiles would use around 54,000 GB of storage. The majority of tiles are never viewed. In fact just 1.79% have ever been viewed. This is because the majority of tiles are at zoom level 18 and the vast majority of those contain nothing of interest (the sea, for example) By following an on-the-fly rendering approach we can avoid rendering these tiles unnecessarily. The tile view count column shows how many tiles have been produced on the OSM Tile server. Tile server disk usage: 1,272 GB used. (6 Jan 2012). (z0 to z15: 252 GB, z16 to z18: 1,020 GB)
  9. Why make your own? Tile Usage Policy You’re in control:

    Design and Content Need tiles in EPSG:27700? 29903? Having OSM Data in a Database enables a lot of things You will learn a lot
  10. www.switch2osm.org Tileserver Software Stack • Software Stack: • mod_tile: apache

    module, serves and expires tiles • renderd: priority queuing system for rendering requests • mapnik: does the actual rendering • postgis: Spatially enabled PostgreSQL database • osm2pgsql: loads osm data into the postgis database
  11. Steps for setting up your own Tileserver • Download and

    install libraries (apt-get) • Install PostgreSQL / Postgis • Install osm2pgsql and Mapnik (python) • Install mod_tile and renderd • Install & configure mapnik style-sheet • Configure renderd and mod_tile • Tune PostgreSQL • Download Planet and Coastline data • Import into Postgis • Start tileserver www.switch2osm.org
  12. Phew! Is there an easier way? • Postgis and Tilemill

    • maperitive.net – Reads .osm / .pbf, exports bitmaps & SVG • tiledrawer.com – Amazon EC2 based rendering / hosting
  13. osm2pgsql Approx 70 Minutes for a small extract (Ireland .pbf

    = 69MB, Planet is 23GB) Would be faster on a machine with more RAM and SSD disks Whole Planet can take days osm2pgsql -s -U username -d gis -C 100 /path/to/downloaded/osm/data -s = Slim mode -U = postgres username (owner of gis database) -d = database name (usually gis) -C = amount of memory in MB, usually 800, but my PC is a bit old
  14. Using the Data API “The Overpass API (or OSM3S) is

    a read-only API that serves up custom selected parts of the OSM map data. It acts as a database over the web: the client sends a query to the API and gets back the data set that corresponds to the query.” wiki.openstreetmap.org/wiki/Overpass_API overpass-turbo.eu
  15. Extract Raw Data – Embedded in a map <div> on

    a web page map.addLayers([ make_layer("http://overpass-api.de/api/interpreter?data= node[amenity=pub](bbox);out+skel; (way[amenity=pub](bbox);node(w););out+skel;", “Blue") ]);
  16. osmosis – java based command line OSM data processing tool

    Some examples of the things it can currently do are: • Generate planet dumps from a database • Load planet dumps into a database • Produce change sets using database history tables • Apply change sets to a local database • Compare two planet dump files and produce a change set • Re-sort the data contained in planet dump files • Extract data inside a bounding box or polygon wiki.openstreetmap.org/wiki/Osmosis
  17. Spatialite – SQLite Spatial www.gaia-gis.it/fossil/spatialite_tools/index spatialite_osm_map – converts .osm to

    a sqlite format usable in a GIS spatialite_osm_raw – converts .osm to a sqlite format usable for stats spatialite_osm_filter – generates an OSM.XML file masked by an input polygon spatialite_osm_net – generates ‘routable’ data from roads
  18. spatialite_osm_map / raw – importing .pbf file www.gaia-gis.it/fossil/spatialite_tools/index spatialite_osm_map –o

    input.pbf –d output.sqlite Took about 30 mins (compared to 70 for osm2pgsql) Resulting .sqlite file was 300MB for the map, 1.5GB for raw
  19. Left as an exercise: Other services that you can run

    / setup: Nominatim – OSM’s Geocoder. pgRouting – PostgreSQL based routing OSRM – Open Source Routing Machine, closely tied to OSM Using Osmosis to keep your tileserver up to date pgRouting.org project-osrm.org
  20. Wider Issues: Comparing OSM and Commercial Data What now for

    Commercial Mapping? Privacy & Data Protection The future of tiles
  21. VGI: OpenStreetMap • Limited to what is ‘visible’ • API’s

    limited, aimed at data editors • ‘Viral’ nature of data licence • Focus on map data • ‘Warm Geography’ • Aims to be of Public Interest • Instant data updates, Sporadic • ‘Depth’ Issues (coverage, completeness) • Weak Metadata / Standards Commercial GeoData Providers • Wide source of inputs • API’s extensive, aimed at data consumers • Derived data issues • Focus on services • ‘Cold Geography’ • Aims to be Authoritive • Moderated update process, Consistent • ‘Width’ issues (limited featureset) • Expensive
  22. OSM Wiki: wiki.openstreetmap.org OSM Help Forums: help.openstreetmap.org OSM-F Blog: blog.osmfoundation.org

    OpenGeoData Blog (OSM News): opengeodata.org IRC (Internet Relay Chat): irc://irc.oftc.net #osm Mailing Lists: lists.openstreetmap.org/listinfo Contacting OSM
  23. 10 'Takeaways' License Check obligations if mixing data Data Model

    Area / Multipolygon handling is complex Usage Policies Desktop prob not an issue. Server, web different Build Your Own No apt-get install tileserver Yet Tilemill Great for designers, self hosting options exist Shapefiles Easy, not complete Postgis Starting point for many possibilities Data APIs Great for snapshots in geojson or POI webpages Spatialite Spatial Database without the Database Data vs Services Is OSM commoditising data? Is that bad?