[Talk-us] parcel data in OSM

[Brian May]

On 12/28/2012 4:47 PM, Phil! Gold wrote:
> * 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.
>
+1 on all points. I've seen the same things in FL and use parcels as a 
backdrop in JOSM to help guide hand digitizing boundaries for things 
like parks, golf, schools, hospitals, retail, residential areas, etc. 
And as Phil said, sometimes it doesn't make sense to follow the parcel 
lines exactly, such as if the parcel boundary extends into a road and it 
makes more sense to draw the boundary where the park area appears to end 
some distance from the road.

Brian