Tuesday, March 1, 2011

Notes on a Saskatchewan OpenStreetMap Canvec import

  I finally got around to doing my first OSM data import session.  I had some spare time and was frustrated with the lack of OSM progress in Saskatchewan, so I imported a Canvec sub-tile for Melfort, Sask.

    It was surprisingly easy, thanks to the great work of Daniel Bégin in supplying .osm formatted Canvec data, and Steve Singer's blog on  Importing Canvec.

  I used Josm to import the geometry and Potlatch to add the street names (the street naming was tedious, but somehow felt rewarding).  
 
Josm
  Josm looks like a powerful OSM editting tool and can be a little intimidating.  Fortunately you can do a lot with a couple of simple workflows.  Steve's blog covers the basics of opening the Canvec data and downloading the current OSM data for the area.
 
  Now to replace the existing low-res roads in the OSM data with the higher-res roads in the Canvec data, ensuring the new roads connect to low-res roads just outside the import area  
  1. Activate the OSM layer and add nodes to the existing OSM road data at the edge of your import area.  This will make the connecting of the new roads to the existing OSM road network easier.  When a node is added, select the node then click the "Split a way at the selected node" button.  This will let you select just the OSM roads with in the import area.
  2. Select the e
  3. Activate the Canvec layer.  Click "Open a list of all relations". Search. Copy. Edit->Merge Selection. Delete.
  4. Activate OSM layer.  Zoom to each of nodes you added.  Move the OSM node to Canvec node.  Select both nodes.  Tools-> Merge Nodes
  5. Upload

  Now to upload the other relations in the Canvec data.
  1. Since you've deleted the highways from the Canvec dataset in the previous workflow, activate the Canvec data and select everything.  Copy. Activate the OSM layer. Paste.
  2. Upload. A dialog will likely appear showing a list of errors and warnings.  If there are errors, cancel the upload.
  3.  The errors are likely related to duplicated ways of railways.  Delete the duplicates and upload.
  
Road Data
  For others planning to do some OSM work in Saskatchewan, here's a summary of free and license-friendly sources of street GIS data:

Canvec (.osm format)
    ftp://ftp2.cits.rncan.gc.ca/osm/pub
    - old geometry
    - no street names
    - no address ranges

GeoSask Road Network
    ftp://portaldata:freedata@ftp.isc.ca/PackagedData/Sask_Highways/SURN09.zip
    - geometry same as Canvec (old)
    - complete street names, but poor capitalization and spelling: "MACLOED AVENUE"
    - no address ranges

Geobase Road Network
    http://www.geobase.ca/geobase/en/search.do?produit=nrn&language=en
    - new geometry
    - complete street names, poor capitalization and spelling: "Macloed Avenue"
    - no address ranges

StatsCan
    http://geodepot.statcan.gc.ca/2006/040120011618150421032019/1814062006_05-eng.jsp
    - newer geometry but positional accuracy poor
    - incomplete street names (unless you combine NAME and TYPE attributes) "MacLeod AVE"
    - has address ranges