[OSM-dev] Land Information New Zealand (LINZ) -> Openstreetmap import first pass

[andrzej zaborowski]

2009/6/30 Joe Richards <joefish75 at yahoo.com>:
> I've been working on the LINZ data import, on attribution/legal as well
> as the actual import.  The LINZ data I have is actually via the NZ
> Open GPS project

Would it make sense to get access to the original dataset from which
the NZOGPS dataset is generated, before attempting import?  There are
surely things that don't fit in the Garmin format and were left out,
also I seem to remember that format uses 5 decimal digits accuracy
(which isn't terribly bad but using the original values would be
better) (it may have been specific to the Garmin files I had to deal
with and not a general rule, please correct me).  Otherwise, when the
LINZ data becomes available it will take another big effort to merge
data imported so far with new data that became available.

On the other hand I realise it's best to import as soon as possible so
that people can get on with mapping even further details and fixing
any problems in imported data.

>
> I've hacked around with a few other scripts and have created a python
> script which creates .osm files, and then imported them into a local
> postGIS instance I run at home.  From there I've generated tiles using
> Mapnik  and uploaded them to a dev server for your perusal....
>
> Upload is still in progress but most are there already (starting in the
> north and working south).  It's just south of Christchurch already and
> I have gone and rendered Dunedin, Queenstown and Glenorchy ahead
> of time.  If you find zoom 16 is not visible then zoom out a bit until you
> find the available tiles.  As mentioned all of the north island is done.
>
> http://linz.dev.openstreetmap.org/~JoeRichards/
>
> Notes:
>  * import was done on a basic world map (from vmap0) to provide
> coastlines where they were missing
>  * some large rivers have a lot of detail, but some seem to be missing
> altogether (e.g. Lower Hutt river) - this was also missing in the NZOGPS dataset,
> not sure why
>  * tiles are still being generated and uploaded now (Tue 30th June),
> but all of the north island to 16 zoom levels is done as well as the
> Tasman... South of Christchurch is still being uploaded (although some
> tiles are there at lower zoom levels)
>  * I think most of the road types (primary, secondary, trunk) etc
> might be completely off, including the link roads.  Please send me any
> specific instances or comments on this
>  * No attempt made to support anything like turn restrictions or
> relations since this was missing from the original dataset

If you see POLYLINEs with type 0x19, these would be turn restrictions
in the Garmin format, and if you see POLYGONs with multiple DataN
(e.g. Data0) elements, those would be multipolygons.  When I made my
conversion script, before I discovered the multipolygons, I saw
missing objects, like the rivers you notice are missing, which makes
me wonder whether they're coded as multipolygons and not getting
converted.

It would be interesting to make the script you used emit some info of
the number of objects that have not been converted.

http://repo.or.cz/w/ump2osm.git has the script I use for converting
the MP format to .osm, I took the approach to error out on unknown
object types to make sure every bit of information gets converted.  It
has some smart bits like figuring out the class of a roundabout based
on the classes of roads that meet the roundabout, converting address
information (housenumbers, etc), assigning layers (bridges, tunnels),
etc. but I don't know how many of these features were specific to the
dataset I dealt with and how many were part of the garmin format /
Polish Map format.

Turn restrictions are especially painful to add to converted data
afterwards compared to adding during the conversion.

Regards

>
> Source (GPL) is here
> http://trac.openstreetmap.org/browser/applications/utils/import/linz2osm/mp2osm_linz_jr.py
>
> Anything in the code marked as TODO or FIXME requires special attention and verification.
>
> Enjoy and feel free to comment!