[OSM-dev] How to tag addresses
Robert (Jamie) Munro
rjmunro at arjam.net
Thu Jun 14 11:40:51 BST 2007
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Dave Hansen wrote:
> On Wed, 2007-06-13 at 16:14 -0700, Brandon Martin-Anderson wrote:
>> The problem with address geocoding is like this: there is absolutely
>> no national standard for street addressing, let alone international
>> standard. Any and every assumption you make about the way addresses
>> should work can be and is violated all the time. Street addresses can
>> even be out of order, even in some places in the US. The only way to
>> use a single dataset for address geocoding on a national scale is dumb
>> brute force - for every little segment one or more address ranges is
>> specificed for both the right and lefthand side of the street (with
>> respect to the direction the line is traveling, even when the line is
>> a two-way street).
> Sounds sensible. I do worry what happens if, for instance, a segment
> has its direction changed. This is pretty common when people are
> merging ways together. Whatever was doing the merging would need to
> have the knowledge to flip around those address tags.
> Would it be more sensible to make these cardinal-direction-based,
> instead of left/right? Addresses for the north and south sides of the
> street? If the street was perfectly north/south, you could pick either
> east or west to be the surrogate north.
I've previously suggested that you use north/south if the road is within
45 degrees of horizontal, and east/west if it's within 45 degrees of
vertical. If it's bang on 45 degrees, or even just close, you can use
either. This way it won't go wrong if someone moves a node slightly.
>> This his how the TIGER/line dataset works. The OSM may be a bad place
>> to store address range information, as vandals or well-meaning
>> uninformed people could easily ruin it and it would be very difficult
>> to detect. But i figured as long as I'm importing the TIGER dataset, I
>> might as well give it a go.
> It does seem like whatever happens with the TIGER data, we should
> probably at least annotate it well enough in OSM to tell where it came
> from. That way, we could do things like add the addressing information
> at a later time if we have to.
>> I have a proposal for how you could do it with no extension to the
>> TIGER data model. I attached a diagram which illustrates the problem
>> and my idea. In order to keep an address range for a set of segments
>> which may be a small sub-portion of a way, you add a tag to the node
>> which says where the dates start on a particular adjacent segment. For
>> example if a node abuts segment id=23423, where the address is 1440,
>> then the tag would be "address_23423 = 1440".
Sounds like another use for my relationships proposal, but I'd say this
was a relationship between a node and a way. So you could say this node
is at number X of way "High Street".
Robert (Jamie) Munro
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