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
--
Audemus jura nostra defendere...
[Let us dare defend our rights.]
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