In the past year I have worked on the evaluation of OpenStreetMap data. I was helped by Patrick Weber, Claire Ellul, and especially Naureen Zulfiqar who carried out part of the analysis of motorways. The OSM data was compared against Ordnance Survey Meridian 2 and the 1:10,000 raster as they have enough similarity to justify a comparison. Now, as the fourth birthday of OSM is approaching, it is good time to evaluate what was achieved. The analysis shows that, where OSM was collected by several users and benefited from some quality assurance, the quality of the data is comparable and can be fit for many applications. The positional accuracy is about 6 metres, which is expected for the data collection methods that are used in OSM. The comparison of motorways shows about 80% overlap between OSM and OS – but more research is required. The challenges are the many areas that are not covered – currently, OSM has good coverage for only 25% of the land area of England. In addition, in areas that are covered well, quality assurance procedures should be considered – and I’m sure that the OSM crowd will find great ways to make these procedures fun. OSM also doesn’t covered areas at the bottom of the deprivation scale as well as it covers areas that are wealthier. The map below shows the quality of coverage of the two datasets for England, with blue marking areas where OSM coverage is good and red where it is poor.
The full report is available here, and if someone is willing to sponsor further analysis – please get in touch!
The paper itself have been published – Haklay M, 2010, “How good is volunteered geographical information? A comparative study of OpenStreetMap and Ordnance Survey datasets” Environment and Planning B: Planning and Design 37(4) 682 – 703