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It turns out that Peoria is not just a metaphor, but a real place in Illinois. It is also the location of a rather messy GIS import of County data! Here’s the history as far as I can determine:

  • The Peoria County Government gathered data resulting in a dataset as of 1997.
  • In 2010, that dataset was considered old enough to be considered “obsolete” which apparently justified uploading it to OSM.
  • A wiki page Peoriagisuploa describes most of the details of what happened in June 2010. Basically, it’s woods and buildings.
  • Woods came in with natural=wood (but too many nodes)
  • Buildings came in with building=yes and BUILDING_T=(0..9) for a building type, as documented on the wiki page.
  • In July 2010, user account “xybot” applied some changes called “Correction of faulty peoria bulk upload” which did a very strange thing to the building tags. It changed “BUILDING_T” to “tiger:buildingType” (!) There is no such tag in TIGER (which has no buildings, let alone building types).

I studied this mess and figured out what should have occurred: mapping Peoria’s BUILDING_T onto the actual, standard OSM building types:

  • BUILDING_T=1 -> building=residential
  • BUILDING_T=2 -> building=commercial (very few of these are industrial)
  • BUILDING_T=3 -> building=school
  • BUILDING_T=4 -> building=garage
  • BUILDING_T=5 -> building=static_caravan
  • BUILDING_T=6 -> building=industrial (there are almost none of these)
  • BUILDING_T=7 -> building=yes (it was under construction in 1997, it isn’t now)
  • BUILDING_T=8 -> (make these the inner ways of multipolygon relations)
  • BUILDING_T=9 -> man_made=pier

I have been laboriously applying these fixes recently, and will finish soon. I’m doing it manually in JOSM, checking carefully, not only because that’s the quality thing to do, but also to head off any claims of “mechanical editing”. I’m also cleaning up the woods, which is not simply a matter of decimation but also a lot of manual updating because the woods are not where they were in 1997.

Discussion

Comment from Nakaner on 12 April 2015 at 07:29

If an import was a bad import like the one you describe above, it should be reverted, not repaired. If people need really a map in this area they either will reimport the data in better way (simplified geometries, better tagging) or they will map the area by on the ground survey. If there are no mappers in this town, nobody needs the data.

From my point of view, OSM is not the right place for old data. Either import up-to-date data or map it on your own! I would delete the whole data garbage.

Comment from JBacc1 on 12 April 2015 at 11:24

Nice work! Good that someone focuses not on importing, but on the maintenance… even if in this case, it should have been done before the import.

Comment from bdiscoe on 21 April 2015 at 04:43

@Nakaner, it’s not that bad. Really all that was wrong was the building tags, and excessive detail on the woods. The building geometry is actually very high quality and perfectly aligned to Bing, and since most of the buildings that existed in 1997 still exist today, it’s perhaps 99% accurate.

@JBacc1, I agree. Perhaps import procedures have gotten better since 2010? In particular, people are usually better about decimating data, I don’t see extremely excessive nodes very often… except sometimes… I should write another entry about that big subject.

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