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

[Werner Poppele]

Cruz Enrique Borges wrote:
>> "The height of a building gives a lot of information about the people
>> living in that building" - please explain it. For me it sounds amusing
>
> The information about the height is code as "number of floors" in the
> source file (catastro). Even more, you can make a fair guess making
> "3m = 1 floor" (as is what we are doing when exporting).
>
> Now, you have the "total surface" of the building multiplying the number of
> floors times the build surface area. Next, you have several possibilities
> depending of what you are doing and the information you have:
>
> - In the worst case you can estimate the mean number of person per square
>    meter with the population data from the National Statistics Agency.
> - If you have information about the total number of person in the building
>    you can "fain grain" the information. For example, in our work, we have a
>    fair estimation of the number of individual houses that there is in a
>    particular build, so we can have the person/per build information
>    (this information in given by a enterprise and is private but national agency
>    have this information, we are not ).
> - Now you have a estimation of the "local density" of the area. High density
>    areas normally consists of tall buildings in the city centre while low density
>    consists of suburbs areas. And now you can start characterizing the zones
>    if you like.
>
> And most important of all, we are talking about GIS here, if you want or need it in
> the other way, you can create the union of these geometries. But you can't do it from
> backwards, from one building get the separated parts.
>
>>  From the aerial images it looks like 2, maybe 3 free-standing houses for
>> a single family. It is very difficult to determine that from the
>> data you imported because the houses consist of 3 to 5 separate
>> building ways all of them tagged in exactly the same manner.  You
>> will need to do a complicated geometric analysis and add a lot of
>> guess work to determine the actual number of houses.
>
> This could be a problem, but please note that we have the parcel information
> too. With this data you can make the fair guess that you will have one
> building per parcel. Note that the case with non adjacent builds is trivial
> as you can just take the union of all the polygon as the base surface and the
> highest height or, as we are only interested in the surfaces, just take them
> as different builds. Obviously with this kind of guessing you will make lots
> of mistakes. For example in adjacent houses but normally if this case is
> mapped as a whole block and you don have any clue of the number of houses
> or the total surface. Even more, this can be guessed using the parcel information
> an/or the policy number and stuff like that.
>
> Please note that, in this case we are not interested in the "number of houses"
> as this is public information (at least in the Spanish Statistic Agency).
>
> Of course, this type of information complicate the analysis BUT you can still
> make the same calculation your are doing now AND you can do lots of new things.
>
Thanks a lot for your informative answer

WernerP


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