RE: geocoding

If you are limited to the US, you can use the Tiger files supplied
by the U.S. Census. Each line segment has fields like primary name,
secondary name, starting address left, starting address right, ending
address left, ending address right. You can generate the lat/long
by finding the segment by matching the street name, and then
extrapolating to match the street number.

I think one reason companies can charge thousands of dollars is that
the accuracy of the Tiger files is not great. In particular, there
are errors with street names and some (many?) of the newer streets
won't be there at all.

It would be interesting to see a comparison of hit rates. If the
vendors don't provide one, then maybe the Tiger files aren't so bad
after all ... ;)

Also, I think there is an initiative by Galdos, Inc. to provide the
latest Tiger files in GML format, which should be interesting.

--
Mark Bucciarelli    Peregrine Systems, Inc.       R&D, Boston
(413) 253-0020      mbucciarelli@peregrine.com    Yahoo: m_bucciarelli
http://www.peregrine.com 
> -----Original Message-----
> From: Nate Tanner [mailto:Nate.Tanner@knowledgenet.com]
> Sent: Tuesday, July 03, 2001 3:57 AM
> To: 'openmap-users@bbn.com'
> Subject: geocoding
> 
> 
> Hi ya'll,
> I am working on a little project, not using openmap at this 
> point, but I
> figured this was the right crowd for this question. For part 
> of the project
> I basically want someone to come to a web page, enter their 
> address or major
> cross streets, and hit submit. Then I want the server to geocode the
> location and return the latitude and longitude. 
> I've seen some commercial products that cost thousands of 
> dollars that will
> do this sort of thing, but I figure there's got to be some inexpensive
> options, even if I have to do a little data manipulation 
> myself. Where can
> ya point me?
> Thanks in advance for any help,
> Nate Tanner
> -----Original Message-----
> From: Ken Anderson [mailto:kanderson@bbn.com]
> Sent: Friday, June 29, 2001 7:46 PM
> To: Tennessee Leeuwenburg; openmap-users@bbn.com
> Cc: rshapiro@bbn.com
> Subject: Re: printing
> I'm not an openmap developer, and I haven't printed myself, 
> but Rich Shapiro
> has. I think getting transformations and clipping right can 
> be tricky. Maybe
> sending us your code or trying random algorithms might help.
> k
> At 01:13 AM 6/29/2001, Tennessee Leeuwenburg wrote:
> >Hi all,
> >
> >I've implemented printing in Openmap, but I have one 
> persistent problem.
> The image I get has (obviously) the same dimensions as the 
> map. In my case,
> those dimensions aren't the same aspect ratio, and are larger 
> than, what
> will fit on the printable area of an a4 page. This results in 
> clipping. I've
> found that rescaling the image will rescale my printed output, but not
> actually change where the image is being clipped. (i.e. my 
> output changes
> size/ratio, but only the clipped output appear, even though 
> the new size
> would be large enough to accommodate the entire image. Any 
> ideas anyone?
> >
> >-Tennessee
> >==============================================
> >This email contains information which may be useful. The views
> >expressed within may or may not be the views of the author.
> >==============================================
> >
> >-Tennessee Leeuwenburg, Silver Stream Pty Ltd
> >0418 300 881
> >
> >--
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