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

[Lester Caine]

Paul Norman wrote:
>>> 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.

My current practice is to work against 'house number' so I'm slowly splitting 
semi's and terraces so that each has it's own house number. I'm not making any 
distinction between single story and two or more story - something which I think 
the Cadastre data does provide extra detail for but without tags in the raw data 
- only splitting a property where there is a detached garage or other structure 
on the same land parcel. Car ports are just part of the one profile and I'm not 
at the moment mapping 'patio areas' which seem to get attached as buildings 
without walls? Pavement cafe terraces and the like should be correctly tagged as 
such.

The problem *I* am seeing with the cadastre data I have looked at is that a 
building is not simply one or two profiles, but several seemingly unrelated 
elements all strange shapes and not relating to the imagery. Since there is no 
explanation of the detail my feeling was that these SHOULD all have been 
combined into a single element in the raw processing until such time as real 
detail of a difference was available? I'd EVEN be happy with a 'bot' going 
around the current data and combining adjacent or overlapping buildings into one 
where there IS no other tagging? This would at least give a better 
representation of what is known and I believe would substantially reduce the 
number of building elements?

-- 
Lester Caine - G8HFL
-----------------------------
Contact - http://lsces.co.uk/wiki/?page=contact
L.S.Caine Electronic Services - http://lsces.co.uk
EnquirySolve - http://enquirysolve.com/
Model Engineers Digital Workshop - http://medw.co.uk
Rainbow Digital Media - http://rainbowdigitalmedia.co.uk