[Geocoding] General Nominatim questions

[Sarah Hoffmann]

Hi,

On Mon, Oct 15, 2012 at 11:33:17AM -0700, Charles Randall wrote:
> Hey all -
> I've got a couple of random Nominatim questions for the group:
> 
> a. Nominatim accuracy: A number of times, when I put in a specific house
> address for Nominatim, I get back a lat long, which doesnt vary with street
> numbers.
> - I assume this is because of the data files used.

This happens, when the house numbers are not in the database, then the
coordinate of the street is returned.

> - Do people do anything to make these more accurate?

You can always survey house numbers and add them to the OSM database.

> b. Address details option in URL:
> I'm curious, if I set the nominatim query string to have the option
> "addressdetails=1", what exactly is coming back in the data I see returned?
> I feel like the different sets of place id's returned is the lat long
> address details of the other street options that are listed on the main
> screen when you do a query.

I'm not sure I understand that question. What you get back with addressdatails
is a list of the parts of the address together with their designation (street,
city, county, country, etc.)

> c. Are there particular xml files for US address data that some people find
> are more accurate than others?

Not sure how that relates to Nominatim. It's primary source is data from OSM,
there are no other xml files. You'll find different excerpts in the internet
but they all come from one source - OpenStreetMap.

For the US, it can also be made to use Tiger house number data on top of the
OSM data, which will most help with your problem from question 1. I can't 
really comment on the accuracy of this additional TIGER data. Maybe others 
know better.

Sarah