[OSM-talk] house numbers revisited

[Martijn van Exel]

Op 17 apr 2008, om 14:00 heeft Frederik Ramm het volgende geschreven:

> Hi,
>
>> As you can see, I employ four tags to indicate house number ranges:
>> * houseno:left-min
>> * houseno:left-max
>> * houseno:left-scheme
>> * houseno:right-min
>> * houseno:right-max
>> * houseno:right-scheme
>> Left and right are relative to the direction if the way.
>> Min is the first house number on either side, again looking in the   
>> direction of the way.
>> Max is the last house number on either side, looking in the  
>> direction  of the way.
>> Scheme can be one of 'even', 'odd' or 'mixed'.
>
> Pitfalls include:
>
> * what if way direction is reversed?
> * what if way is extended, merged, split?

That will be a problem indeed. Could theoretically be solved with  
strong editor support, but that does not fix the intrinsic flaw. You  
never know when a script comes around that reverses direction for some  
valid reason, outside the editors. Someone on talk-nl suggested using  
a NSEW-based tagging scheme, but this is not unambiguous either.
>
> * what if way provides access to houses with the address of another  
> way (corner buildings typically - house is on A street but entry is  
> from B street)
> * what do you do with letters? At least in Germany they sometimes  
> have 2, 4, 6a, 6b, 6c, 6d, 6e, 8...

You could override the ranges with individual tags on the buildings,  
but I guess the buildings would have to have a relation to the way then.
>
> * what if there are gaps in numbering? split the way?
Either that, or accept that there may be nonexistant numbers in the  
range
>
>
> Some of this may not seem to important but I would really like to  
> have house numbers on the map, and if at all possible I'd like to  
> avoid printing a number that doesn't even exist.

I'm hadn't even thought of actually having house numbers on the map,  
but for routing / geocoding they can be extremely useful.

> [...]

> A completely different (and quite OSM-like!) option is dropping all  
> this complex logic, left-right-blah tagging, number schemes,  
> relations and all, and just put simple nodes: "This is B street  
> number 25". This brings redundancy, typos, and all - but we're used  
> to that. It would be *extremely* easy to edit, and renderers or  
> routers would have to do a little bit of processing to work with the  
> data. Not too hard probably.

I like it for its obvious OSMity. The schemes could co-exist I guess.
>
> I'm not saying either of these is best. We'll have a little "house  
> number hacking workshop" here in Karlsruhe where some of us will try  
> and decide on a working scheme and implement this in a renderer/ 
> editor if possible, and enter a few house numbers for the local  
> area, just to see if it works.

Interesting. Keep us informed!



-- 
martijn van exel -+- mvexel at gmail.com -+- http://www.schaaltreinen.nl/