[OSM-talk] All you've ever wanted to know about the french cadastre

[Paul Norman]

> From: Martin Koppenhoefer [mailto:dieterdreist at gmail.com]
> Sent: Saturday, September 29, 2012 5:21 PM
> Subject: Re: [OSM-talk] All you've ever wanted to know about the french
> cadastre
> Am 30.09.2012 um 02:04 schrieb Paul Norman <penorman at mac.com>:
> 
> > in a city where the buildings are joined). A complete analysis is
> > beyond the scope of this email, but we can get an idea from [2] and
> > the fact that the most common unsimplified building area in the import
> > is 6 square meters[3]. This indicates that the case of a  building way
> > with attached ways to represent the porches and other attached areas.
> 
> I guess these are mainly garages and car ports, not porches

The distribution of building sizes indicates otherwise. The most common
building size in the cadastre imports is a mere 6 square meters (65 square
feet). Wikipedia gives the area of a Ford Fiesta as 7 square meters, and
that doesn't leave any room to open the doors. You might be able to fit a
Smart Fortwo into a 6 square meter garage but I doubt you'd be able to open
the doors.

Just for reference, the 1950s garage at home that barely fits a small car
though the entrance has an area of about 17 square meters.

> > If you assume wall=no buildings attached to buildings without a wall
> > tag can be combined, I would estimate that the number of ways is at
> > least 1.5x what it needs to be.
> 
> -1, I'd suggest building=roof for those that are roofs. IMHO it is nice
> to distinguish them. Why do you think that mappers wouldn't do this as
> well?
> If it's different buildings attached to each other they shouldn't be a
> single blob.

In the recent talk@ discussions most mappers who commented on the issue of
how they'd normally map the examples given said they'd do it as one
building. If we were talking about houses and garages or carports I could
see doing it as two, but as indicated above, these aren't that large.