[Tagging] tagging the multipolygon model (was landuse and military)

[Ben Laenen]

Pieren wrote:
> It doesn't fail so much because most of the time, landuse values are
> exclusive (residential, industrial, forest, etc). It is already enough
> complicated to add polygones or multipolygones for landuse. We can see
> that this is only done in countrysides or small urban areas but not in
> towns/cities. We cannot ask people to create a second polygon which
> will most of the time be a copy of the landuse : "land covered by
> buildings used for residential" or "land covered by trees used for
> trees farm". I think we should better enforce landuse to be exclusive
> by removing the non-exclusive values like military.

Residential isn't exclusive at all. Not to say that what it's actually used 
for in OSM can have different meanings amongst different mappers. You'll find 
many parks in OSM for example inside a residential polygon. I've never seen 
holes in a landuse=residential polygon at locations where shops are. By far 
most uses I've seen for landuse=residential are for areas which are generally 
used for where people live, and usually have entire villages or cities inside 
one polygon. That's not ground cover, that's telling what the area is used 
for.

Proper ground cover would have no such thing as a "residential area". It would 
have tags for "building" (and subtags for what kind of building it is), or 
"garden".

I'm not saying that current landuse=residential/industrial/... doesn't have 
any merit. It's quite nice to make maps for big areas. But at the level where 
you start to show individual buildings only proper ground cover can be used.

Either the landuse=residential/industrial/... kind of tags have to move out of 
the landuse key, or we have to come up with something new.

Now, ground cover in OSM is made up of several tags under different keys (like 
natural or landuse), while same keys can often be found to map usage instead 
of ground cover, resulting in conflicts (like the original discussion of this 
thread where landuse=military can also be many other things; a farm could have 
crop fields, meadows, orchards, ). It's just such a mess now and things need 
to be split up and thoroughly revised or we'll regularly end up in discussions 
like this in future.

Ben