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

[THEVENON Julien]

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Le mer. 26 sept. 2012 21:48 HAEC, Lester Caine a écrit

>Looking at the source material, there is nothing which can be used to separate the blocks displayed into separate buildings, and since we have no means of identifying different levels of building, adding 'detail' for that seems pointless? All that can be 'accurately' extracted from the source material is that there is a 'block' of buildings? So if you are not actually surveying the buildings and identifying individual buildings, then normal practice is to draw a single box. Frederik's example is the sort of thing that SHOULD have been tidied up before importing.

please don't forget that you are talking about something that is considered as a bad import by the french community and that you are currently focusing on one building whereas there thousand correct buildings imported by hardworking mappers.
you also seem to consider that there is only cadastre in the life. majority of contributos also use there local knowledge. I personnaly know where buildings are separated in my city and where there is a single one or at least I can go to check directly. I don't know by heart the number of level for each building and I have other priority at the moment(I prefer to concentrate on missing roads by example) but I think it would have no sense to remove correct details provided by cadastre just because I cannot had the details at the moment. a mappers keen of micro mapping or osm2xp will just have to add the missing details if he want.

Please don't consider that what you think useless is useless for everyone. few weeks ago we had a request from a guy that would like to use osm data to compute solar energy potential production. For the moment this not possible but it can be done by adding some tags to separated adjacent building to indicate orientation of roof. by keeping only the external shape of building block it will not be possible

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>Hand tracing hundreds of individual elements and not committing them often does not make sense. What I am talking about here is selecting hundreds of vectors from a file without checking them, and having to select each individually would help the checking process. Then perhaps the sort of questionable mapping demonstrated would not happen?
>Personally I would prefer to see http://www.remote.org/frederik/tmp/funnybuilding.png as a single closed outline box. If the vectors are not providing closed objects then there is something wrong with the data anyway and in my book it should not be allowed to be imported? With a decent editor, one should be able to select the outline of a block and simply import that ...

where did you see open building objects ?

cheers
Julien