[OSM-talk] Large cadastral polygons

Paul Johnson baloo at ursamundi.org
Fri Jun 12 15:37:06 UTC 2020

On Fri, Jun 12, 2020 at 10:28 AM Florian Lohoff <f at zz.de> wrote:

> On Fri, Jun 12, 2020 at 02:14:15PM +0200, Mateusz Konieczny via talk wrote:
> >
> >
> >
> > Jun 12, 2020, 13:59 by f at zz.de:
> >
> > > Changeset envelopes which span more than 100s of km² are broken.
> > >
> > Except cases where you edit/delete already created huge objects or you
> create
> > huge object that actually should be created.
> >
> These types of objects should be pretty exceptional. I try to split
> landuses to sub 1km² because i also feel the pain for
> rendering tiles. As soon as someone touches those areas you invalidate
> tons of tiles. So breaking this down also benefits us long term
> concerning workload on the tile servers.

Not just that, but cadastral type tags probably shouldn't be spanning large
areas to start with.  If your landuse or landcover polygon is crossing an
unclassified or higher highway, you're probably making a big mistake.
landuse=residential is NOT a substitute for place=neighborhood (something I
see a lot).

If you have reasonably high resolution (like, at least Esri Clarity in the
midwest) imagery available, it's often possible to see lot stakes and
fenceposts on property boundaries...that seems like a reasonable edge for a
landuse polygon.  Also makes it easier to deal with landuse changes in the
future, as lots rarely change shape, more commonly get subdivided or
consolidated; that's a trivial change.
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