Last week we added new data to the geocoding service that resolves addresses down to their exact location
This means that we are now able to return two latitude / longitude pairs per address - one that represents the middle of the address land parcel (for Display), and one for where the address connects to the road network.
Fortunately, this is one of those features where a picture is worth a thousand words, so I will stop trying to explain it and just show some differences
Address Point Geocoding difference
The red star shows where a regular geocoding data set would place the address
The blue star shows where we now tell you the center of the address parcel
The green star shows where we know the address connects to the road network
In the screenshot above, the red star represents where a regular interpolated geocode would place the address on the road. Regular geocoding data does not actually contain every single address on a road. instead, it normally contains the length of the road, and the range of house numbers along the length or the road (e.g: 1-99 Main Street). So if you looked for 50 Main Street, math would be used to work out the approximate location of where #50 probably is between #1 and #99
However, with the new Address Point data, we know the actual physical location of each particular house. So, in the screenshot above, the blue star shows us the center of the physical land parcel - as you can see, its a LOT more accurate!. Then the green star shows where the actual address connects to the road network, so we can really deliver you right to the doorstep of the location you are trying to get to.
Here is where we need your help, faithful reader. Adding Address Point Data represents a massive increase in the size of the data we are using in our geocoding service, and we are load-testing before we roll out to full production. Please take the time to hit our Beta geocoding service at http://platform.beta.mapquest.com/geocoding as much as possible.
when using the service the response will inform you if it has resolved to a Point in two different ways.
Firstly, the GeocodeQuality node contains a pure text description like this (JSON):
Secondly, the GeocodeQualityCode will start with a "P1" for the granularity value - like this:
For a full understanding of the geocodequalitycode value and what the different response values mean, the GeocodeQualityCode page in the documentation breaks it all down
Lets finish this post with some more screenshots that show the accuracy difference of address point versus interpolated geocoding