[Talk-us] Staleness view

Martijn van Exel m at rtijn.org
Wed Jul 4 18:05:08 BST 2012


Thinking about good locations for a mapping party, or just about where
to go by yourself for a mapping session, can become harder in places
where the map is pretty much complete looking.
Looking under the hood can be helpful. For example at the age of the
data. Older data is more likely to need updating that data that was
just edited a little while ago. Of course, this is a significant
simplification, but knowing where data has not been updated for a
while will be helpful for QA and targeting mapping efforts.
I started a prototype of 'staleness' visualization and I'd like to
hear what you think. The main reason is that we will be running a
mapping party in DC on July 15th and we were talking about where to
go. So I did the analysis for DC[1] initially, and then for
Amsterdam[2] to see if it made sense in a totally different community
/ geography setting. I think it shows data staleness in a nice, not
too cluttered way, but I'd love to hear your thoughts. Should this be
rolled out on a wider scale? Integrated with existing tools? (it's
just a shapefile with a geoserver WMS on the back end, pretty
portable.) There's some more background in a blog post[3] and the
thing is on GitHub[4] if you want to see how it was done.
Some ideas I have myself are (for another couple hours of
procratination, of which there should be few):
* grid-based analysis with averages per cell instead of individual
data points. Looks more boring, but may have better information value.
* Doing a 'stale POI' specific map / web service. Isolate meaningful
POIs and serve those up. Stale POIs are particularly likely to need
some updating; restaurants and shops change owners and close all the

[1] http://mvexel.dev.openstreetmap.org/dcstaleness/
[2] http://mvexel.dev.openstreetmap.org/staleness/amsterdam.html
[3] https://oegeo.wordpress.com/2012/07/03/a-look-at-stale-openstreetmap-data/
[4] https://github.com/mvexel/staleness
martijn van exel

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