OpenStreetMap
MapRoulette Challenges 'Ways Needing Smoothing' and 'Crossing Ways' Completed
Posted by mvexel on 3 October 2014 in English.If you have logged in to MapRoulette today, you may have noticed that the Ways Needing Smoothing and Crossing Ways challenges are now gone. There is a simple reason: they are done!
Congratulations!
Together, we resolved more than 100 thousand suspected ‘sharp angle’ errors in the Ways Needing Smoothing challenge, and just under 25 thousand crossing ways in the Crossing Ways challenge.
So at least for the United States, we now have much less of this:
.. and many less situations where two ways cross but should really have an intersection node. (Sorry, in this case an image does not say more than a thousand words..)
Not all suspected cases turned out to be real errors. For the crossing ways, about two thirds of the cases were eventually marked as ‘fixed’ by MapRoulette users:
For the Ways Needing Smoothing, the fixed rate was much lower, about 40%:
This low rate can be explained in part by MapRoulette users fixing more than they are asked to fix! What I heard a lot is that mappers would load a smoothing task in their browser, and ending up spending a lot of time cleaning up the area around the error - often resolving other MapRoulette tasks without even knowing it. So it’s not as bad as it looks, and I received mostly really positive feedback about this challenge.
I have a new challenge in the pipeline that also has to do with TIGER fixup - a separate diary is forthcoming about that!
As always, if you have a good idea for a challenge, don’t hesitate to get in touch with me so I can help you get started! Better still, subscribe to the MapRoulette mailing list and share your ideas with the MapRoulette community!
Discussion
Comment from Be A Mapper on 3 October 2014 at 22:24
Well done.
Martijn, I really like what you and Serge are doing with maproulette.
Comment from SimonPoole on 3 October 2014 at 22:34
Martijn, congrats.
I may have asked this before, sorry if I have: the ways need smoothing task at least motivated some mappers (well at least myself) to clean up the surrounding areas (i remember correcting a larger city where all the roads were more than one block off, OSM based navigation devices would have miserably failed there), has there neen a noticeable improvement in routing quality in the US after completion of the task?
Simon
Comment from mvexel on 3 October 2014 at 22:54
Be A Mapper, thanks! I hope for more good challenges in the future.
Simon, thanks. Yes, there would be a noticeable improvement in routing quality for those particular locations where TIGER misalignment is really bad. Scout is pretty forgiving when it comes to determining which road you are on - as are most GPS based navigation systems - but where it gets really confusing, like this for example:
…you will get wrong guidance and ‘rerouting…’ prompts consistently. In those places, GPS based routing applications will immediately benefit from targeted improvements. I have a similar challenge lined up that identifies OSM ways that are significantly misaligned from more recent (2014) TIGER data, which should help resolve some of the remaining TIGER mess.
Can you believe we are still cleaning this up, 5 years after the import?
Comment from raykendo on 6 October 2014 at 15:42
Great job everybody! I had a lot of fun with those challenges.
For the “Ways Need Smoothing” challenge, another possible reason for false positives that I noticed were Interstate crossovers, splits, and merges. They would look super sharp as you cut over from the northbound lanes to the southbound lanes, for instance. I ran into a few of these. Some I smoothed out, and others I skipped because I wasn’t sure.