[OSM-talk] Yet another street number scheme

[Frederik Ramm]

Matias,

> Is there anything inherently wrong with this system? 

No, it is just another way to do it. If you feel it suits you better 
than the existing schemes, use it.

> I wrote it thinking about ease of editing and efficiency both in storage and 
> for use by software, most schemes I have seen are bad in two or more of 
> those.

You will not find a scheme that has no problems. One big problem with 
yours is that if a way is split in two, then things become veery 
difficult; you basically need an editor plugin that then splits the 
relation into two as well, with the nodes from one half of the way in 
one relations and the others in the other. Splitting ways is a 
relatively common operation I think.

Also, you are re-using the existing nodes in a street. This means that 
if someone moves these around to improve the shape, the house numbers 
move with it which might not be desirable. - What happens if you have an 
extra node beside the way (e.g. a pharmacy) for which you want to add a 
house number?

With the current state of editors, I cannot see the "ease of editing" 
you talk about.

As for the efficiency in storage, I suggest you take the long-term view: 
I am 100% sure that at some point in the future, OSM will have at least 
one node for every house, more likely a building outline for every 
house. Look at this if you don't believe me:

http://informationfreeway.org/?lat=51.03267406093207&lon=13.718639663339111&zoom=15&layers=B0000F000F

At this point it will be trivial (easy to edit, easy to handle, and 
requiring little extra storage) to simply add a house number tag to 
every one of these buildings. Any sort of complex relations for roads 
with interpolation rules for house numbers will then simply be 
unnecessary. Your scheme is not suitable for giving a number to every 
single house on a street (of course it *could* be done but would become 
very cumbersome), so you will have to phase it out slowly and replace it 
by direct tagging.

The Karlsruhe schema which I use surely has its flaws as well, but the 
"long term view" is already built in there - you can tag individual 
houses now *or* you can do interpolation, and there's a (IMHO) rather 
seamless transition. The schema is widely used already (325k house 
numbers tagged world-wide), and we'll soon also have a cool debug tool 
for it that helps you spot problems (or omissions) in numbering.

But of course, you can try out your own scheme as well. With a little 
programming effort, every one of them can be converted into the other 
anyway.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"