[NUUG kart] Import of norwegian administrative boarders

Gnonthgol gnonthgol at gmail.com
Wed Aug 22 16:34:57 CEST 2012

The norwegian mapping agency have several datasets called N50, N100, ..., N2000, N5000 where the number indicates what resolution it is made for. So N2000 is made to be printed on 1:2.000.000 maps etc.

The current administrative boundaries in OSM are mainly from an import done some years ago when their N5000 dataset was PD. The only source we found however was a WMS and the import was not according to the current procedures. It was done by several mappers on their personal accounts and the source tags was therefore not consistent.

Since then the mapping agency made the N5000 dataset "free" by putting a CC BY-SA license and publishing it in vector format. The 20th of April this year they did the same with the N2000 dataset, but after a few hours silently changed the license to CC BY. This makes it available for importing to OSM in both CC BY-SA and ODbL.

After studying the shapefiles and asking the mapping agency I know that they have created the N2000 data by taking their original data and simplified it with 500m and 300m accuracy (depending on boundary) and then manually correcting. On their roads layer I have seen that their "correcting" involves moving the elements so that they do not overlap. I have not seen this on the boundaries yet, but we have to look for such things when we are importing. The data we are importing consists of 17693 nodes

My plan for importing this is:
0. Use a separate account only for this import
1. Open the shape file in josm
2. Download an area of norway from xapi with all the ways with the tag boundary=administrative
3. Copy all the nodes from the shapefile to the downloaded layer
4. Go through all the nodes manually and add them to the existing ways or merge them with existing nodes
5. Remove the source tag on the ways where that is appropriate
6. Upload on the import account and add import=yes and a source tag on the changeset (I will not add a source tag on all nodes)

This will preserve the existing way and node ids, manual contributions and all relations. It have been discussed on the norwegian mailing list.


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