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

[andrzej zaborowski]

Hi,

On 27 February 2013 22:45, Sarah Hoffmann <lonvia at denofr.de> wrote:
>> In the Spanish list there is a rather consensus that it is worth to upload
>> that data. Moreover, in this particular thread someone said that it would
>> be a shame that we does not import that information because it would be
>> very useful. However in the wiki about how to use Cat2Osm we have written a
>> note, telling that 3d tags can create too many geometries and that the mapper
>> should decide whether to use it or not.
>
> Usefulness is in the eye of the beholder. While you may find it interesting
> to have all this 3D information, I'd find it much more useful to have building
> outlines in OSM that are complete. The single building parts make not much
> sense for anything but 3D rendering. And I suspect that they are going to
> give you a big headache once you get around to mapping addresses.

I was one of the people arguing for keeping the height information in
the data but I proposed to possibly use a compromise between keeping
all of the polygons and dropping all 3d information.  Some
possibilities are:
* merge the shapes but also merge the building:levels tag using the
max value of those merged,
* use a weighed median,
* only merge polygons with surface area < 10 square metres.
* only merge if building:levels difference is <= 1 floor or similar.
* some combination of the above.

However I'd be wary of saying "such and such information only makes
sense for such and such use".  I see this sometimes in the local
forums where people argue we can remove information not useful for
their routing or rendering.  There are many creative uses of OSM data
that we can't know about.

Cheers