[OSM-talk] Proposal for import guidelines

[THEVENON Julien]

>>>> De : Lester Caine <lester at lsces.co.uk>

>>>> Sees the light :)
Great !


>>>> SO while we have this type of raster data from as a background in 
potlatch and josm and some elements of it in vector files from OS and 
other sources. You are having to stitch together 'pictures' and then 
your 'automatic processing' is recreating vector data from the 
'pictures'?

I don`t know all details but yes this is something like that


>>>> I understand the problems now ... and it only really works because the pictures can be simply vectorised.

yes has pdf is vectorised but if i rember well what you see as a simple yellow rectangle is an overlay of different rectangle inside pdf code explaining partly why we have some geomtry problems with contigous buildings.


>>>> SO I would be asking if the 'pictures' can be merged to create a single 
raster overlay for France to use as a background 'source' which could 
potentially be used to trace from, but can be used in conjunction with 
BING imagery to corss check?
The French cadastre licence doesn't allow us to redistribute cadastre data as they are so I think it is not legally possible to do that.
The other issue is related to projection : Mercator for Bing and Lambert 9 zones for French cadastre. In addition to that not all the french cities have vectorised cadastre data. There are still a lot of cities which have raster data that are just scan of cadaster paper plan without georeferencing ( Feurs in 42-Loire by example )


>>>> I would classify that as my base import 
since it's not externally available? We have several versions of the OS 
data along with the historic maps for the UK, and I feel sure that 
should be achievable in France as well?
I don't know if some people are interested in historic maps or such kind of map aspects in french community

>>>> The vectorised files are 
the 'staging layer' and I'm sure that since you are providing each 
building as a shape then in the future it should be possible to maintain a 'building_id' that can be used with the sort of merge tools I am 
looking for to handle this type of data?
We have a tool called "bati fusion" that try to perfom a diff between OSM files to make merging easier by using building shape comparison I think but I don`t know if it is massively used. I personnally know the guy who developped it if you are interested

Cheers
Julien
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