[OSM-dev] missing nodes
marqqs at gmx.eu
marqqs at gmx.eu
Tue Oct 16 17:33:10 BST 2012
Hi David,
did you find out exactly where in your toolchain these nodes get lost?
Maybe it's the filter process with Osmosis? I wouldn't assume a bug, I think it's more likely a misunderstanding in how the program options should be used.
I'm not sure about the official API definition but it might be perfectly normal that not every noderef has a corresponding node in the file.
If you do cheap extracts (e.g. with osmconvert without "--complete-ways" option) the way objects will not be modified. Each way object will stay complete, even if all of its nodes (but one) has been removed from the file.
Regards
Markus
-------- Original-Nachricht --------
> Datum: Tue, 16 Oct 2012 16:40:18 +0100
> Von: David Prime <david at primefarm.co.uk>
> An: dev at openstreetmap.org
> Betreff: [OSM-dev] missing nodes
> Hi All,
>
> I'm relatively new to processing the OSM datasets and trying to extract
> interesting data. What I'm trying to do is build a dataset of all UK
> roads.
> I first used osmosis with a way filter based on the highway tag, which
> worked reasonably well. However, when I delved into the data, I noticed
> that a lot of my ways had node refs to missing node entities in the file
> I'm extracting data from (a recent england dump). Now, I expect some roads
> to get chopped off at borders and so on but I've done it manually via a
> java program that parses the full england dump and I've counted
> ~1.3million
> ways which reference nodes that I could not find in the same XML file.
> This
> seems excessive to me, unless I'm misunderstanding some aspect of the data
> model. Any ideas from the old hands?
>
> Many thanks,
> David
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