creating named buildings


I’ve been trying to figure out the consensus about creating named buildings in OSM. I’ve seen 3 different ways of handling things in well developed map areas.

1) Just put a single point, and the name key filled out (maybe with additional info)
2) polygon with building:yes and name filled out
3) polygon with building:yes (maybe even name and other info filled out) + a single point in the middle of polygon with name, etc… (many times more extensive information on the point than on the polygon)

My question is, which one of the 3 should I use if I want to make good quality maps:
1) probably not, since if I more info such as the building outline, then it should be included

2) does this display the the name (and additional icons like “museum”) properly on the map after rendering? because if yes, then no need for 3)

3) is used extensively, but seems to me to duplicate information in a non-trivial way (from the point of of view of the renderer)

I think I’m in favour of 2) (polygon only with building=yes) but would like to hear the opinion of more experienced people…

I use both 1 and 2. The way I see it, 2 is a better level of detail, which means if you are in the mood for a bit of more detailed mapping you should definitely go ahead and draw in the building outline.

You could also convert things from approach 1 to approach 2 when you’re bored. This is clear-cut good contribution when you’re working with your own nodes. Of course when converting other people’s nodes, there’s a chance you might receive complaints or criticism for fiddling with somebody elses data, but in my opinion this criticism would be misguided. Going from individual nodes to building outlines is always a good improvement in the level of detail.

BUT… mappers shouldn’t feel bad about taking a shortcut and just doing approach 1. Approach 2 is a better level of details, but is certainly not “required”, and approach 2 involves a lot of fannying around with the editor, so consider this: What is more useful? An entire town of buildings mapped out as nodes, or just one neighbourhood with all the building outlines done. Nothing wrong with approach 1.

Approach 3 shouldn’t really be used, See Good Practice. “One feature, one OSM-object” …but another common approach in a city context, is to draw a single outline of a building which then contains several features tagged as individual nodes. e.g. a row of shops/cafes in a city block. That seems fine to me.

There’s lots of “level of detail” questions when mapping, particularly when you start mapping house numbers! Generally more detail is better (more “depth” to the data if you like) but don’t burn out your editing energy on that kind of thing at the expense of mapping more features (more “breadth” to the data)

Thanks for the clear explanations Harry.

I have a follow on question.
I’ve mapped a building using point 2, however it’s a two storey development, with the same footprint.
It is a supermarket with a library on top.

How would I name these? I looked at the Level tag but I’m unsure how to have separate names?

Any Ideas?

Dave F.

Yeah I don’t know either to be honest. The situation crops up quite rarely, since most interesting amenities are on the ground floor, especially where they are large with significant building outline. Quite often I’ll see things like dentists on a floor above, or restaurant in the basement, but with a ground floor entrance, so then I’ll tend to tag the entrance with a node (alongside other nodes for shops appearing at ground level)

But when it comes to building outlines and libraries above supermarkets, I don’t know. Stick a note= tag on there and forget about it :slight_smile: Mind you it has probably been discussed at length in the mailing list archives somewhere.