[Talk-us] parcel data in OSM

[Phil! Gold]

* Jason Remillard <remillard.jason at gmail.com> [2012-12-28 16:16 -0500]:
> So the question is, what should the exact criteria be for including an
> "open space" parcel in OSM. Consider some of the various types of
> property.

I've used parcel data as a layer in JOSM to trace from.  It lets me be a
little more accourate about some area boundaries than I could from just
aerial imagery (and walking a GPS along, say, the border between a golf
course and a residential area with private houses is a little out of the
question).

I'd be resistant to the idea of bulk import (pretty much anything beyond
pulling individually-checked polygons into OSM) because I've seen a lot of
places where a naive import of the parcel data available would have made
for wrong or at least weird OSM data.

I've seen a number of places where a single entity acquired its land over
time, so the parcel records show multiple parcels that should be a single
OSM entity.  Similarly, I've seen a lot of places where a public road cuts
through a single entity's land (golf courses especially, but also parks
and residential areas).  I feel it's more correct to make a single polygon
that crosses the road, but parcel data would usually have the road
splitting the area.  I've also seen a few places where parcels were too
broad, where a single parcel needs to be divided into several different
OSM landuses.

This is just my experience with the handful of counties in Maryland that
have parcel data available under an OSM-friendly license.  Maybe other
jurisdictions have data that would provide a more one-to-one
correspondence with OSm features.  Even in those cases, an importer would
need to make sure that the import fits topologically into OSM, interacting
properly with existing data.