[postgis-users] Adding to geocoder data for better results?

[Stephen Frost]

* Kent Richards (info at kentrichards.net) wrote:
> When geocoding some addresses (perhaps, unincorporated areas), the returned results are not even in the ballpark.

That really depends on what parts of the address you trust.  If the zip
codes in your data are 100% accurate then you could modify the geocoder
to fall back to using that if the street isn't found (or the city, of
course), but...

> select * from geocode('46896 California 1, Big Sur, CA 93920');
>                          addy                          |                      geomout                       | rating 
> -------------------------------------------------------+----------------------------------------------------+--------
>  (,,California,Via,,,"Dana Point",CA,92624,t)          | 0101000020AD10000073368950A46A5DC082C23F6CC5BB4040 |     38
>  (,,California,Via,,,"Dana Point",CA,92675,t)          | 0101000020AD100000CCE9BF1EA76A5DC05EB5F600C9BB4040 |     39
>  (,,California,Via,,,"San Juan Capistrano",CA,92675,t) | 0101000020AD1000006679E728A16A5DC0467CB31001BC4040 |     40
> 
> Dana Point, CA is ~350 miles from Big Sur, CA.
> 
> The search zip (93920) doesn't appear to be in zip_lookup or zip_lookup_all.
> 
> "Big Sur" doesn't appear to be in place.

It sounds like this is a large part of the issue to begin with- if the
zip code and place aren't known to the geocoder, I'm not really sure how
you expect it to be able to produce a better answer based on them...
Unfortunately, the USPS still (afaik) wants to charge for public
information like zip code data.  I'm not working with the USGS data much
any more, unfortunately, but you could also make sure that you're using
the latest data from them (they release once/year, last I checked).

> I have voter registration data that includes full addresses for registered voters.  Is there a way to add this data to the geocoder tables so that geocoding returns something in the ballpark for addresses such as this?

If you have geolocation information (POINT data) for those addresses
then you might be able to incorporate it into the geocoder data, but I'm
guessing you don't or you wouldn't be using the geocoder to begin
with, and I don't see how just addresses could help with geocoding...

Another option would be to look at using the OpenStreetMap data.  I had
intended to and more-or-less just never got around to it.

	Thanks,

		Stephen
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