[postgis-users] Geocoder for PostGIS

[Rich Gibson]

Hi David,

A postgis solution basically just didn't work when Schuyler first
implemented it.  The data and indexes were about 40 gb, and
performance just didn't cut it.

The flexibility of a SQL solution would clearly be nice, but Schuyler
couldn't make it work effectively (ie. fast enough).

Interpolating along the line, rather than endpoints, is not
particularly hard-and is something we've considered adding.  It will
add some space to the database, but not horribly so.

Cheers,
Rich

> 
> Schuyler's solution with BerkleyDB relies on specific import routines
> and hard coded hashes that hold the mappings to find street types and
> directions.  If this approach were broadened to have a shapefile
> import with configurations and mappings held in separate files we
> could make it suit our needs.  The result would likely be faster and
> it would have the advantage of being a stand alone solution.  The
> drawbacks though would be precision (Schuylers approach just
> interpolates between road endpoints not along the line -- not a big
> deal for most applications, but important for some) and ease of
> customization -- with a SQL database solution it is possible to ease
> the creation of new localizations using SQL.  For example, the way my
> geocoder is set up is so that I can create my base street type
> mappings by selecting the unique streettypes from my roads dataset
> into a new table.  That table then has two columns one with the
> "correct" form of the street type and one with a regular expression to
> map any other common ways of depicting that street type (ie RD,
> R(OA)?D )  I have to fill in the regular expression column by hand,
> but it is easy as I know all and exactly all of the street types used
> in my data. These little customization shortcuts would be, in my
> opinion, more difficult to create outside of a nice SQL environment.
> 
> On 8/15/05, Abe Gillespie <abe.gillespie at gmail.com> wrote:
> > I disagree with making a universal geocoder depend on PostGIS.  I
> > think it's a better idea to have it completely independent of PostGIS.
> >  Once it works on its own, say a separate library, only then should it
> > be rolled into PostGIS.
> >
> > -Abe
> >
> > On 8/15/05, David Bitner <osgis.lists at gmail.com> wrote:
> > > I've got my PL/PGSQL / PL/Perl geocoder at http://foo.gyttja.org.  I
> > > have tried to develop it so that it could have different types of
> > > datasets plugged in.  I'm all for getting a standard base.
> > >
> > > I would propose keeping the work completely within the database, I
> > > have found that PL/Perl is great for the address parsing, but it adds
> > > a requirement for the user.  Additional "clients" could then be added
> > > for PHP or Perl or ASP or whatever to access the PostgreSQL/PostGIS
> > > geocode function.
> > >
> > > In order to make a worldwide geocoder, we should keep as many
> > > components of the geocoder separate as possible so that we can reuse
> > > as much code as possible between localizations.  The two
> > > functionalities that will change between geocoders depend on the local
> > > way of presenting an address (ie 4000 East Harriett Parkway,
> > > Minneapolis, MN 55560) and the type of dataset geocoding agains (do
> > > you have both left and right address ranges, can we make a function
> > > that geocodes off parcel data).  We should also have some functions to
> > > standardize and index the information in the source data.
> > >
> > > On 8/15/05, Stephen Woodbridge <woodbri at swoodbridge.com> wrote:
> > > > Paul,
> > > >
> > > > I think we might need to define the code and/or development environment
> > > > also. For example is it going to be:
> > > >
> > > > 1. inside postgres
> > > > 2. php, perl, C, java, etc or one language and wrappers, etc
> > > >
> > > > It would be nice to see a design section that would be organized by
> > > > country that people with local knowledge can update with country
> > > > specific addressing requirements and address parsing requirements, etc.
> > > >
> > > > A data section, that is more oriented to identifying data sources as
> > > > opposed to storing data by country might be useful.
> > > >
> > > > Just some thoughts,
> > > >    -Stephen Woodbridge
> > > >     http://imaptools.com
> > > >
> > > > Paul Scott wrote:
> > > > > On Mon, 2005-08-15 at 05:29 -0400, "René F. Viancos S." wrote:
> > > > >
> > > > >
> > > > >> Someone knows an opensource development  for geocoding in PostGIS
> > > > >> and/or PHP
> > > > >>
> > > > >
> > > > >
> > > > > Seeing as though this thread comes up with _alarming_ regularity, I
> > > > > propose that we *start* a project for exactly this.
> > > > >
> > > > > We could divide the source tree by country, and let everyone
> > > > > interested contribute some country specific code. Once that is done,
> > > > > try then to create a generic "world-geocoder" of sorts. I am sure
> > > > > that the Mapserver Community would also like to get involved.
> > > > >
> > > > > I am prepared to host such  a project, as well as provide additional
> > > > > mailing lists etc, to keep it off this list (eliminating unnecessary
> > > > > mail to uninterested parties).
> > > > >
> > > > > Comments? Thoughts? Flames?
> > > > >
> > > > > I could have this set up in a matter of minutes, so let me know. I
> > > > > think that this project will create some respite for all users of
> > > > > this list :)
> > > > >
> > > > > --Paul
> > > > >
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