[Tagging] Lyft and nameless sectioning in OSM

[Greg Troxel]

Evan Carroll <me at evancarroll.com> writes:

> *FOLLOW UP HYPOTHETICAL: *
> I've been thinking about this a lot. I'm arguing here that,
>
> * Landuse for developed land can be better automatically generated when
> there isn't a named polygon.
> * If automatically generated, we can achieve perfect accuracy or quantify
> the margins of errors (the degree to which a buildings adhere to the
> landuse that contains them).

I do not understand 'automatically generated'.  Landuse is about the
primary human use of the land, and that's something that has to be
obeserved, or come from another dataset (as an import) where it was
observed.


> Let us create a new landuse-esque tag called "density"
> Let density come in three flavors, "density=high", "density=low",
> "density=medium"
>
> * Low Density is where you have mostly single story buildings
> * Medium Density is where your buildings average to five or fewer levels.
> * High Density is where most of your buildings have more than 5 levels

That's not landuse in the traditional geography sense; you can have
hi-rise residential and hi-rise office and one is residential and the
other commercial.

And, if the buildings are on the map and labeled with levels, then
there is no need to tag what you are proposing.

> What would be ideal: (a) to have users create these polygons in OSM, or (b)
> to automatically calculate density as a function of the buildings in the
> polygon by referring to building:levels? This is a direct analogy to how I
> see unnamed landuse for developed land.

For density, it seem a, but for landuse it is perfectly reasonable for a
mapper to observe that an area is filled with shops and add a
landuse=retail polygon.  It may be that a building or so within that is
commercial not retail, but that's ok.

>  There is an application for
> landuse, and for density. However, I don't understand why these are better
> left to users rather than automatically generated. If we want to support
> landuse for developed land moving forward, I highly suggest automatically
> inferring it from the contents of polygons created in the method outlined
> in my reply to Joseph Eisenberg. =)

Part of the issue is that landuse should more or less follow property
lines, unless there is some reason why not.  a several-acre parcel with
a house and some trees is still landuse=residential on all of it, absent
farming or some side industrial business.

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