Inconsistency found in Geofabrik OSM exports ?

Hi,

I'm using the geographic .osm subsets generated by GeoFabrik that can be downloaded here:

http://download.geofabrik.de/osm/europe/france/

However, in some of them, I found some strange ways definitions (missing nodes), this sounds to me like a mistake from their side, a kind of inconsistency that occurs during the generation of those subsets. However, as I'm relatively new to OSM, maybe you can confirm that this is a mistake from their side.

Here's the definition of the way 23301557 in their file: (with only one node in it) alt text

And here's the way it is defined in OSM : http://www.openstreetmap.org/browse/way/23301557 alt text Some nodes seem to be missing.....

Can you confirm me that this is due an error on the geofabrik side and not something I'm missing in my use of the .osm file ?

Thanks a lot.

geofabrik

asked 15 Feb '11, 14:02

y0n3l
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One Answer:

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What you are seeing is the result of these extracts being created with the Osmosis option --clipIncompleteEntities=true - whenever an object crosses the border of the extract, then only the part of the object that lies inside is actually included in the extract.

Osmosis has two other options how to deal with these situations. One is --clipIncompleteEntities=false which would in your case lead to a way that references all the right nodes, but these nodes would be missing in the file. Geofabrik doesn't do that because the inconsistent files would trip up some users. The other option is --completeWays=true in which Osmosis would collect the extra nodes and add them to the output file even though they lie outside the area in question. This is not used by Geofabrik because it takes too long.

If you cannot work with this file, you will have to use the next larger extract (e.g. france.osm) and then cut out your area of interest yourself with a suitable set of parameters.

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answered 15 Feb '11, 14:09

Frederik Ramm ♦
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accept rate: 23%

edited 15 Feb '11, 14:18

Jonathan Ben...
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Thanks for your detailed answer. I would have prefer to avoid using the france.osm but if that's the only way :/ Would you know a "fast" way to get all the nodes that refer indirectly to a relation ? I "just" want ways / nodes for a predefined administrative boundary ( http://bit.ly/ifGan3 ) should I parse the france.osm "only for that" :/

(15 Feb '11, 14:27) y0n3l

Ok I think that the easiest way to do what I want is to rely on the api and ask for the members of the relation using http://api.openstreetmap.org/api/0.6/relation/7411 and so on for the ways and then the nodes..... As the api also supports multi fetch, this is a nice and fast solution.

(15 Feb '11, 14:42) y0n3l

This is not necessary. You can use http://api.openstreetmap.org/api/0.6/relation/7411/full to give you all referenced objects. However don't do any of this on a regular, automated basis - it's ok for a one-off.

(15 Feb '11, 14:50) Frederik Ramm ♦

Thanks a lot for the tip ! Yes I only need to do it one time for some relations.

(15 Feb '11, 14:53) y0n3l

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question asked: 15 Feb '11, 14:02

question was seen: 5,572 times

last updated: 15 Feb '11, 14:54

Inconsistency found in Geofabrik OSM exports ?

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