Steve Chilton of Middlesex University recently created a cool map in GeoCommons comparing street coverage for OpenStreetMap (OSM) and Google/TeleAtlas in several cities across the globe. It provided a fascinating perspective and thought it would be cool to share it with the community.

The project began with work by Bernard Zwischenbrugger to visually compare coverages between OSM and Google/TeleAtlas. Then Alex Mauer picked up the ball and did a numerical analysis of coverage. Steve then took Bernard’s original visual comparison (location data) and Alex’s scoring (numerical comparison) and produced a map to visualize the results of the comparison:

The size of the circles are proportional to the values for both, so small circles equal poor coverage and large circles equal good coverage. The overlap of the circles shows who appears to be doing better (orangey/brown showing means that osm is doing better, blue google). OSM is the top layer so a tie will have OSM looking better, but you can click the layers on and off to see both views of the coverage.

Alex’s original assessment was that OSM is slightly ahead of Google/TeleAtlas worldwide and in in Africa and Asia. In Europe, OSM is well ahead. Google is slightly ahead in Oceania, and well ahead in North and especially South America.

Steve would have liked to be able to show results on a combined scale from +5 (for osm 5, google 0) to -5 (osm 0, google +5), with 0 for equal, but we do not yet ha ve a bi-polar colour scale for point data in the software. A great suggestion for future development.

It will be interesting to see how Google’s launch of MapMaker for 162 countries will impact this comparison in the future. Many thanks to Steve for loading the data into Finder and making cool maps with it.


16 Responses to OpenStreetMap vs. Google/TeleAtlas Street Coverage

  1. Menno says:

    Nice map…

    One small comment though: in the article it is said that “In Europe, OSM is well ahead.”. From what I see this is not the case, Google is ahead of or equal to OSM within the countries of the European Union and well ahead within the countries of the mediterranean basin (except for Italy). The only countries where OSM is scoring (much) better than Google are the countries of the former eastern europe, the independent states that made up the former soviet union and Scandinavia (including Iceland). To say that OSM is well ahead of Google within Europe seems somewhat simplistic. What I think that can be seen clearly in the map is the strength of an initiative like OSM within countries that have limited resources to publish up-to-date datasets at street level (many African countries) while in countries with a strong cartographic tradition (for example the former British colonies) Google has been able to tap these resources and is ahead of OSM.

  2. Sean Gorman says:

    Hi Menno – Alex is an OSM member, so might have been a bit biased on the coverage comparison ;-) I think the current state of the map is probably more a reflection of where TeleAtlas has made investments to map countries. TeleAtlas is in the business of selling data, so seems logical they will invest in mapping countries in detail where they can make the most money.

    I’d wager Google’s goals are a bit different since they do not sell data. Instead they are looking for viewers of their maps which opens a wider net. I think this is probably one of the motivating reasons behind MapMaker. The street data vendors were not mapping areas where Google had significant visitors from, most likely because they were not profitable markets to map in detail. So, Google created a tool to do so. I think the consensus is it would have been better to incorporate OSM in this effort, but that is a different debate. The nice thing is with the data mapped out it opens the discussion in a new way, for fresh perspectives like yours. Thanks to Steve for that!


  3. hash says:

    Very interesting! I didn’t realize that OSM was so far ahead in W. Africa, which is particularly useful for me to know for Ushahidi.

  4. I just want to clarify that the map only compares (most) capital cites and not countries. Unfortunately the way the map was embedded in the blog page curtailed the title which included this information. There are people within the OSM project working on metrics for measuring both accuracy and coverage at neighbourhood/county/country levels – both of which need to be quantifiable for the data for it to be accepted (and used) widely in the geo-community.

  5. Sean Gorman says:

    Thanks for the clarification Steve. Look forward to seeing the new metrics. In the spirit of crowdsourcing another blog pointed out that Munich was accidentally geo-coded or mislabeled as Monaco. Can’t wait to get annotations on the map so the feedback is harnessed in a systematic manner.

  6. Menno – well, it depends on what you compare. As a traditional streetmap for drivers, Google Maps is still ahead of OSM pretty much everywhere in the EU, you’re right.

    But OSM is ahead with cycle routes (, footpaths, and a bunch of other stuff not shown on Google Maps – even if you take the dreaded ‘mashups’ into account. I can actually use OSM as a cycling or walking map in my area now; certainly can’t say the same for Google.

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