OpenStreetMap

Adding in missing roads from South Australian open data

Posted by CloCkWeRX on 7 October 2013 in English (English)

http://data.sa.gov.au/dataset/roads is CC-BY-A and explicitly OK'd to go into OSM; and more importantly contains every road in SA as of about March 2013.

I'd import it if I could be bothered fighting the technical challenges. The main problem is not the pain of converting the shapefile to something OSM understands, but avoiding duplication given the granularity of modelling in both datasets.

Instead, I'm spending a little time using OSM Inspector to find clusters of unnamed roads and fixing them by hand.

I'm doing this by:

  • Using QGIS (sudo apt-get install qgis)
  • Loading the shapefiles provided
  • Changing the rendering to show the road name as a label
  • Manually inspecting the shapefile to discover street name + type (it also contains surface, width, etc info)
  • Correcting OSM

It'd be nice to evolve this from manual processes into a few automated sanity checks (find a list of all unnamed ways, find the corresponding candidates from the shape file, present to a user), and in the other direction provide the dataset providers a GeoRSS feed of new changes - particularly if people map into new areas; where for example OpenStreetMap currently has the most detailed maps of the St Clair Redevelopment.

If you want to lend a hand, or shepard the import of suburb boundaries through the import process, please reach out :)

Comment from SK53 on 7 October 2013 at 13:45

A fairly naive approach is to buffer existing OSM roads (try 10,20 & 50 metres) and then do a difference operation between the buffered roads & the SA road data. Obviously you'll lose roads within the buffer distance of existing roads but it will probably identify the vast bulk of roads which are missing.

Will probably work best in PostGIS rather than directly in QGIS unless you have loads of memory.

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Comment from Mappo on 9 October 2013 at 15:57

For inspiration, there was at least a couple of projects in the UK that dealt with crowdsource assimilation of similar data:

http://humanleg.org.uk/code/oslmusicalchairs/

http://wiki.openstreetmap.org/wiki/OSM_and_OSL_differences_analysis

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