[postgis-users] RE: geocoding

[David Bitner]

I'm probably the person that you saw in threads working on a plpgsql
geocoder.  Ralph is right, it is much more of a text parsing problem
than a spatial problem.  PL/PGSQL and PL/Perl (great for splitting the
text into component parts with regular expressions --  ie
streetnumber, streetname, street prefix direction etc.)  together with
good indexes and precalculated fields (like metaphones of the
streetnames) can make a very effective text parser and matcher just
utilizing what's good about the PostgreSQL database itself.  Throwing
the line_interpolate_point or centroid (if a polygon based geocoder --
from parcels or zipcodes etc.) from PostGIS into the mix is just
iceing on the cake.

On 5/20/05, Ron Mayer <rm_postgis at cheapcomplexdevices.com> wrote:
> Ralph Mason wrote:
> > Randy George wrote:
> >>     Address => longitude, latitude
> >>
> > I cant answer your question specifically, but it's not a spatial
> > problem, more text processing / parsing.  PostGIS really would add noshing.
> 
> I think postgis does indeed help in some ways.
> 
> For one example, using "line_interpolate_point(geometry,proportion)"
> to avoid writing the code to walk the MULTILINESTRING yourself.
> 
> Another way PostGIS can help geocoding is handling "dirty" addresses
> that often incorrectly have the neighboring zip-codes or cities on
> streets close to borders.  An indexed spatial query to provide a bit
> of extra tolerance around zip codes & cities is one way of helping
> those cases.
> 
> 
> I think a couple additional functions they're thinking of adding
> to postgis (something to find the tangent to the line at that point
> so you can put a point to the left or right of a street?) will
> eventually help even more.
> 
>      Ron
> 
> PS: and yes, Paul, we're still looking for the $$$ to hire you
>      guys to help us with that ;-)
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