On Thu, Dec 20, 2012 at 5:03 PM, Adam Franco <adamfra...@gmail.com> wrote:
> Hello All, > > I'm pretty new to the OSM community and have gotten involved through a > hobby project analyzing road > geometries<https://github.com/adamfranco/curvature/wiki>. > I live in Vermont, a state where more than half of the road-miles are > unpaved graded-gravel. For the benefit of my project and hopefully the OSM > community I have been working outward from my home tagging highway > surfaces <http://www.openstreetmap.org/user/Adam%20Franco/edits> as > gravel, asphalt, or concrete based on direct observation as well as looking > at high-resolution aerial imagery where available. > Welcome! I lived in Vermont for many years, and can certainly attest to the poor nature of some of the roads. Sometimes the asphalt roads were in worse shape than the dirt ones, except for those washboard roads. > What I am interested in doing is bulk-tagging the surface of roads based > on public data where no surface tag has been manually set. Before I begin > this project (and pester my department of transportation for data) I wanted > to check with the community about the permissibility and feasibility of > this effort. > Glad to see you're interested, and especially glad that you came to the list to get the community involved. > A few questions: > > * Has anyone located a good source for state or national road surface > data? The TIGER data doesn't seem to include surface information as far as > I can tell. > I've seen condition tagging on many Massachusetts roads, which I believe came from the MassGIS import. I believe that was a wholesale import and replacement of existing data at an early point, rather than data being conflated. * While the devil is always in the details, I'm assuming that a relatively > safe import could be done by only adding tags to ways that don't have > surface tags already. Are there other considerations I should be thinking > about related to not worsening the OSM data? > What you would do is automatically add the tag if none exist, and then flag any conflicting items for later manual review. However by far your biggest issue is going to be conflation of this data. First, you'll need to match roads between the two datasets, which is a significant challenge. The bigger challenge would be to automatically split the OSM roads at the points where the surface data changes in your dataset. I've never seen anyone do this. The more doable approach is using the dataset as a second layer with JOSM or Potlatch to manually conflate. You might even be able to write a JOSM plugin which would help with this, perhaps extending the conflation plugin I started a while ago. Also Potlatch has some functionality thanks to Cyclestreets to help with this sort of thing: http://wiki.openstreetmap.org/wiki/Potlatch_2_merging_tool > * Is this a project that the OSM community in Vermont, the broader region, > or nationally (assuming data is available) would support? I'd rather not do > a lot of work to prepare it if there is no desire for inclusion in the data > set. > I would say absolutely, but if you truly want automatic bulk conflation, you've got a long hard road in front of you unless you have some mad skills. Even then you'd need to demonstrate it to the community that it works without bugs. Using JOSM or Potlatch for manual conflation seems like an easier path, if not as exciting or fast. Also, think about how to show this data. Consider creating a custom map rendering that shows these surface tags, as it will be good motivation to contributors. I'm sure others will chime in with more thoughts. -Josh
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