In March 2008, I started comparing OpenStreetMap in England to the Ordnance Survey Meridian 2, as a way to evaluate the completeness of OpenStreetMap coverage. The rational behind the comparison is that Meridian 2 represents a generalised geographic dataset that is widely use in national scale spatial analysis. At the time that the study started, it was not clear that OpenStreetMap volunteers can create highly detailed maps as can be seen on the ‘Best of OpenStreetMap‘ site. Yet even today, Meridian 2 provides a minimum threshold for OpenStreetMap when the question of completeness is asked.

So far, I have carried out 6 evaluations, comparing the two datasets in March 2008, March 2009, October 2009, March 2010, September 2010 and March 2011. While the work on the statistical analysis and verification of the results continues, Oliver O’Brien helped me in taking the results of the analysis for Britain and turn them into an interactive online map that can help in exploring the progression of the coverage over the various time period.

Notice that the visualisation shows the total length of all road objects in OpenStreetMap, so does not discriminate between roads, footpaths and other types of objects. This is the most basic level of completeness evaluation and it is fairly coarse.

The application will allow you to browse the results and to zoom to a specific location, and as Oliver integrated the Ordnance Survey Street View layer, it will allow you to see what information is missing from OpenStreetMap.

Finally, note that for the periods before September 2010, the coverage is for England only.

Some details on the development of the map are available on Oliver’s blog.

Are SatNavs dangerous?

31 July, 2008

The Daily Mirror recently put out a summer story on the risks of using SatNavs. While I would question the statistics and the reliability of the information, as it is probably based on a quick phone survey of 2000 people and then extrapolated in some unclear manner, I do think that we need to understand more about the tunnel vision that SatNav devices create in user’s mind.

The problem of showing a users only small section of reality without the full context is surely the right way to provide information in a short burst that does not risk them too much. While I still want to see some research on how long do users look at their SatNavs using an eye tracker (if anyone is willing to sponsor this – we’ve got the equipment!), I’m confident that there is solid reasoning behind the visualisation as it is now.

So, although this is suitable visualisation, we have an unintended consequence of tunnel vision view of the environment through which the user navigates. We are now starting to see some of the misshapes that occur due to this, and that is an area that requires more research and understanding.

See also the comments in the recent Interactions by Elisabeth Churchill about SatNav

During the Intenrnational Cartographic Conference in Moscow last August, one of the presenters, while discussing GeoVisualisation, showed the Röyksopp (2002) ‘Remind me’ clip. As it is has been so long since I’ve followed MTV, or music videos on YouTube it was the first time I had seen it…

The common comment on this brilliant videoclip is that it is about infographics. The designers of the video stated that

“as graphic designers we appreciate the way statistics can describe the whole world. It’s funny and frightening how the smallest aspect of the way we live can be translated into numbers. It also shows how predetermined our lives can seem from this point of view.”

However, there are some interesting Geographical aspects: notice how much of the information is spatial and how scale plays an important role in the transitions between different visualisation. Other Geographical notions that this video prompts are Globalisation, Western Urbanisation, the culture and geography of consumption and surely several more.

Interestingly, 3D representation is not so central and much of the information is provided through 2D representation.

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