[Imports] [Cat2Osm2] Tool for exporting Spanish Cadastre data in OSM suitable format

Cruz Enrique Borges cruz.borges at deusto.es
Thu Jan 17 09:31:36 UTC 2013


Hi everyone,

We sent a message to imports list a few months ago when we finished
the first version of Cat2Osm. This is the results of almost two years
of work back-to-back with the spanish OSM community. It is a tool for
converting a whole municipality's spanish cadastre data [1], to an OSM
file for then checking manually some small errors cadastre could have,
fix them and import the necessary data into OSM. Please notice that
this is not meant to be a tool to mass import, in fact it is a tool to
help local mappers to improve existing data or having a good starting
point in empty places. We repeat, this is not an automatically import
tool!!

The first version exported too much data and created lots of relations
so we've been working with spanish OSM community on a second version
of Cat2Osm2 [2], that simplifies the result by losing some extra info
like:
- reducing the number of relations.
- not taking in account building levels
- create the union for all rural areas which share the same tags
- pass building tags to parcels and remove the building when their
geometries are the same

It also exports the result divided in urban/rural blocks which makes
it very easy for users to validate everything is ok, remove
unnecessary geometries and merge it with existing data. We also export
in separate files linear or points elements that can be also 
interesting to import.

What the spanish OSM community mainly wants to use from the result is
urban related data such as: buildings or parcel landuses and rural
landuses. However, Cat2Osm2 also exports street geometries that could
be suitable for checking if the existing street data is correct or
have a good start point. In fact the import list have already allowed
the use of this kind of data.

Here's a link with the result for a village called AldeasecaDeAlba in
Spain [3]. If you look for Aldeaseca de Alba in OSM [4] you will see
it almost has no data (only street without names). Cat2Osm2 exports
the files separately as we previously said but it also concatenates
them into a global big file just in case someone wants to use the
result for his own GIS or for a quick review of the result. You will
find all this files in previous link. Please note that the concatenated
files is only intended for debug actions and the actual import process
will be made with the split files inside the directories.

Once they've exported the result, at least two users have to review
each block before upload. We have already some wiki infrastructure to
coordinate this actions [6] but probably it would be better to have
a more productive one. 

There exists a import guide [7] with the general information in 
English and a user guide [5] with tips that will be updated when local 
mappers gain more experience working with this data. Please notice that 
this work-flow will change as it is based on the use of the last 
version on an specific city and cannot be suitable for other places. 
We have already created imports accounts (one per province) [6] and 
distributed to some expert users that would be in charge of the upload 
process. We will be very strict with the process; we will not allow to 
upload data with other accounts and if somebody does not respect the 
rules we will ask the admins to take the appropriate action against 
them as we have already done on several occasion.

We hope you find this results suitable for being uploaded in those
places where some data is needed.

[1] http://www.sedecatastro.gob.es/
[2] http://wiki.openstreetmap.org/wiki/Cat2Osm2
[3] http://paginaspersonales.deusto.es/cruz.borges/AldeasecaDeAlba.zip
[4] http://www.openstreetmap.org/?lat=40.81818&lon=-5.44678&zoom=17&layers=M
[5] http://wiki.openstreetmap.org/wiki/Minitutorial_para_cat2osm_Avila
[6] http://wiki.openstreetmap.org/wiki/Spanish_Cadastre/results
[7] http://wiki.openstreetmap.org/wiki/Spanish_Cadastre_import

-- 
Cruz Enrique Borges Hernández
Email: cruz.borges at deusto.es

DeustoTech Energy
Telefono: 944139000 ext.2052
Avda. Universidades, 24
48007 Bilbao, Spain



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