[NUUG kart] kartverket imports to OpenStreetMap

Tyrfing OSM tyrfingosm at gmail.com
Tue Oct 15 10:51:45 CEST 2013

I have recently used N50 from Kartverket as one of my sources for manually
editing the map, and I was one of the people Norman asked to explain (OSM
user name Tyrfing).
I'm not using the data set as source for an automatic/scripted import, but
as a source from which I manually extract data. I'm selective on which
objects to extract, and I have the local knowledge needed to verify the

N50 (also known as M711) from Kartverket (The Norwegian Mapping Authority)
is the official Norwegian 1:50000 topographic maps (or at least the data
from those maps). Most of the information is quite accurate. The data sets
are available under the CC BY 3.0 NO license.

The area where I have been using N50 as source is my main mapping area
(where I also do edits based on Bing, gps, survey and local knowledge). The
area is a mountain area in the south western part of Norway, which I know

I have mainly been editing lakes, wetland and streams based on N50 as a
source. Most of these objects are not mapped in OSM for that area before.
Those that exist are mostly based on low res Landsat or Bing images (lately
the Bing coverage has improved a lot).
So most of the objects I have added is new. Some existing objects have been
updated (keeping history, changing geometry and maybe tags), but then only
if my new object is an improvement (this is exactly the same way as I would
update objects using e.g. Bing as a source).

My workflow has been (not necessarily in exact order):
1. Select a limited area.
2. Download OSM data and gps traces.
3. Manually selecting the objects from the N50 source which I want to
edit/work with in that session, and merge them onto a new layer.
4. Manually check/verify/tag each object. This includes:
4 a. Manually checking against existing OSM/gps data. Deciding if I will
keep the existing geometry or update them (either complete or partial).
4 b. Manually fix the direction of each stream based on local knowledge.
4 c. Tag objects using the regular tagging scheme, just as I would if I
used e.g. Bing or gps as source.
5. When I'm happy then I manually merge each object into the main layer.
This includes:
5 a. Connecting ways with existing data.
5 b. Creating multipolygons if needed.
6. Based on local knowledge I might then choose to add a some extra objects
from the N50 source. That might include some prominent peaks or major paths
(and paths only if they do not exist in OSM before, the OSM paths in this
area are more accurate than on the official Norwegian maps).
7. Adding additional info/tags based on my local knowledge (like names,
operator information or features like cairns, sac_scale, trail_visibility
The last two steps I might reapeat over several changesets (after browsing
the map). Then the next time I would choose an adjacent area, thus
detailing the map in "my" area organically.

I don't consider this use of data from Kartverket as an import, but as
manual editing using an external source, comparable to using e.g. Bing as a
source. The main difference is that N50 as a source is more accurate and
faster to work with.

As Ramm mentioned the data sets from Kartverket are quite extensive. Parts
of it might be suitable for importing (like admin borders or names). But
that I think I will leave to those that actually (want to) do imports.

2013/10/14 Frederik Ramm <frederik at remote.org>

> Dear kart at nuug.no readers,
> (Cc to imports at openstreetmap.org)
>    I am writing to you in my role as a member of the OSMF Data Working
> Group. Our job is to watch out for vandalism, mapping disputes,
> copyright violations, and problematic imports.
> It is the last of these that I'm writing to you about. A number of
> different users have conducted imports from "kartverket" data sets in
> the recent past. Many of these imports had technical problems - e.g.
> changesets filled with 50,000 nodes and thus very difficult to handle,
> or often we can see that people first imported something and then
> deleted half of it again, and so on.
> Importing is a difficult process and you can easily make a lot of
> mistakes. That's why we request that any import is discussed before it
> is conducted, so that experienced data importers can have a look at the
> plans.
> While I have been told that this particular import has been discussed on
> this list, it seems that either there were not enough experienced
> importers on this list, or they have not succeeded in making sure that
> this import runs smoothly. Also, the data that could potentially be
> imported seems to be on a scale that warrants wider discussion.
> I must ask everyone to stop importing any data from the kartverket data
> set for now. Please read and follow the guidelines linked from
> http://wiki.openstreetmap.org/wiki/Import (e.g. note the points about
> separate accounts for data imports), and discuss your import plans with
> the wider community on the imports at openstreetmap.org list.
> Among other things, we will want to understand:
> * what data is scheduled for import
> * how is that data converted to OSM - what tags etc.
> * who does the imports - if it is a community import, how will you make
> sure that people have enough local knowledge and technical knowledge to
> do it right
> * how will conflicts with existing data be handled
> I know this might sound a bit like we're trying to spoil your fun - but
> we aren't, we just want to make sure that the import is indeed a success
> for everyone.
> If we find that any individuals are importing kartverket data before the
> required consultation on the imports@ list is over, we will remind them
> of this. In severe cases we may have to revert an import gone wrong.
> Thanks
> Frederik
> --
> Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"
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