Geocoding is the assignment of geographic coordinates to a location, typically one identified by name or address. I’ve covered address geocoding in an earlier post, in connection with converting US addresses to points in a KML file for use in Google Earth. Reverse address geocoding refers to finding the address closest to a set of geographic coordinates, and I’ve found a website/webservice that will do this for US addresses.
The Geonames Reverse Address Geocoder mashes Google Maps and TIGER address data to create an interface for reverse geocoding a geographic point into the nearest address and street intersection. Here’s a screen shot of the site:
Clicking and dragging moves the Google Map around; while there’s no zoom slider, clicking on “+/-” will zoom you in or out, and you can use the overview window in the lower right to select a region as well. You select a spot on the Google Maps window by clicking on it, and a pink marker balloon is placed on the map, as in the picture above. The site then uses US Census TIGER data to come up with the closest address, and closest screen intersection, to the selected point:
It also displays a list of street segments closest to that point in the pane below the map image, along with the range of addresses associated with that segment. Click on the links in the “Street” column, and those street segments will show up in pink on the map, as in the screenshot above.
If you want to plot a specific geocoded address on the map, enter it into the “geocode addresss:” box above, and the site will use the Google geocoder to come up with a location for that address and mark it on the map. But if the address you geocode using this box is off the displayed map, you won’t see it. Reverse geocoding for both intersections and addresses is available as a web service; scroll down to the bottom of the page for info on how to do that.
The following web site has lots of tools and links for transcoding location info:
http://www.nearby.org.uk/