[OSM-talk] Advanced Relationships

[Laurence Penney]

Existing nodes (but not 2-nodes) could be hijacked for house number 
tagging.

For direction finding, that's really enough - the route itself has 
been found and all you have to do is interpolate between nodes to 
estimate when to stop.

ViaMichelin has a decent presentation of house numbers on this OS 
MasterMap derived map:

http://www.viamichelin.fr/viamichelin/int/dyn/controller/Cartes-plans?mapId=-t4dsv31kx5qcye&dx=192.5&dy=412&empriseW=691&empriseH=562

The following examples refer to the OSM node where New Row joins St 
Martin's Lane. To decide which street the numbers applies to, we could 
repeat the street name(s):

    house_number=80 St Martin's Lane|28 New Row

Or superway IDs:

    house_number=80(superway:45923845)|28(superway:45353432)
    (assume that ID is added by a tool)

Or we could use compass directions and record the side of the road:

    house_number=80(W)|28(N)
    or house_number=80(270)|28(0)

    |
    |NE
  NW|N
   W ------
  SW|S
    |SE
    |

In the diagram, N and S are references on the E-W road, NE is the 
first house on the E side going north away from the junction on the 
N-S road; the W indication would normally be used for the house facing 
the junction, but the SW and NW indications would be used if the N-S 
road's name changed as it passed the junction.

For higher resolution, I think building/address nodes and building 
perimeters are the way to go. Include the street name in the node name 
to avoid ambiguity. (And have something that can easily receive the 
PAF when it becomes available for free!)

However I'm concerned that any numbering scheme piggybacking on 
existing nodes - especially if we try to record which side of the road 
it is - is too fiddly for users. Since in some areas there will 
inevitably be full address and building data using nodes and 
perimeters, why not use that throughout?

-- L


Frederik Ramm wrote:
> Hi,
> 
>> Very simply, you tag a node on a way as 'house_number: 50'. You then
>> tag a node somewhere further along the way as 'house_number: 70'. So
>> if you're looking for house number 60 on that street, it's between the
>> two. Of course, someone can also come along and tag a node as
>> 'house_number: 60', giving more precision. No extra editor support
>> required.
> 
> We might also use extra nodes - not nodes making up the way, but  
> nodes sitting on their own to the left and right. This would separate  
> the road itself from the houses which is a good and a bad thing at  
> the same time:
> 
> A good thing, because the location of house number 70 is fixed, it  
> doesn't change if someone decides to change the road (e.g. add a  
> previously-unmodelled extra parking lane and such). On a detailed map  
> (like OS Landranger maps) you'll even have indiviudal houses as  
> little squares.
> 
> A bad thing, because it is not always obvious to which road such a  
> "number node" belongs. That's probably the same problem that has been  
> discussed a while ago, and applies equally to bus stops, telephone  
> cells and so on - we do not currently attach them to a road, and  
> association is by proximity only.
> 
> Bye
> Frederik