Geocoding is the process of turning an address, city, state, zip or postcode into mappable coordinates.
Batch geocoding using our service is as easy as pasting in a list of location. BatchGeo uses the Google Maps Geocoding API, known to have some of the highest quality data available. Other services require you to write code or manually geocode addresses one by one, but our service performs everything you need to do in a few easy steps.
First the street is found by matching the street name, direction and street type against a block range in the street center line database. The point is set a certain distance from the street center line, after all the building is not likely to be in the middle of the block. However there is no good way to know just how far back from the center of the street the building is, so it's guessed. Usually this is a global value set when the geocoder is configured. Generally you would pick around 50 feet from the address block. There is no way to know for sure how far back the building or building entrance is located, but 50' is usually close.
The final step (and least accurate) in the geocoding process is to try to approximate a location along the block using the address number. Reason being is the address range on your average block face is a nice big range like 1000-2000, or 100-200. However on average there only exists a dozen or less properties on a block. The geocoder does not actually know how many properties are located on the block, the centerline data does not indicate this. In fact it's not even sure if the address is really there or not. You can test this yourself by going to our single address lookup tool and entering an address number on your block that doesn't exist.
The geocoder's best guess about where the address might be located on the block is done by taking the street number calcing it's position along the centerline using the block range. Example: If the range was 100-200, and the address number was 150, the geocoder would place the point halfway along the block range. Again, this is a guess at best. If the geocoder manages to place the point right on top of the address it is just getting lucky!
Other things can help the accuracy, like setting an offset from the start of the block range (similar to the offset from the center line.) The geocoder does know which end of the street to start the calculation from (for example does the 100 address start on the north end or south end, east or west.) But for the most part, geocoding is not that accurate when looking at precision beyond the block range.
Our geocoder uses the Google Maps Geocoding API, which wherever possible utilizes actual parcel information, so geocoding is far more accurate.