Geocoding is the process by which longitude and latitude
coordinates are added to an address record. In some cases the address can be
enhanced with additional data such as census data, parcel boundaries, and
property characteristics.
Geocoding data can be used for
Location Based Services (LBS), which are a general class of computer
program-level services that use location data to control features. LBS include
services to identify the location of a person or object, finding the nearest
ATM, or the whereabouts of a friend. LBS
includes parcel tracking and vehicle tracking services, and can also include
mobile commerce when taking the form of coupons or advertising directed at
customers based on their current location. In addition, the technology is used
for distance mapping, spatial searches, and for Geographical Information
Systems (GIS) where geographic data is stored and analyzed, helping management
gain a more complete view of their customers and prospects.
There a four major geocoding levels each with differing levels of precision.
This does not mean, however, that lesser levels of accuracy are not valuable or
without necessary applications for business.
The most accurate level of geocoding
is rooftop to the delivery point. This is a geocode showing precisely where a
parcel or package can be delivered to, such as the front door or the postbox of
a property.
A secondary level of geocoding
precision is obtained by using interpolated data. The word "interpolate"
means to calculate an estimate based on known values. This method incorporates street
data where the street network is already coded within the geographic coordinate
space by applications like Navteq and TomTom. The Geocoding
engine takes an address and connects it with a street and a specific series of
house numbers. It then interpolates the position of the address within the
segment.
The third level of geocoding is
street centroid data and this denotes the center of a street that an address is
located on. This is done by dividing the streets into segments based on known
coordinates at the beginning and end of a street. This is used when more
precise geocoding information is not available.
The two broadest levels of
geocoding are ZIP™ centroid and city centroid. The returned centroid in these
cases does not indicate the exact geographic location of an address, but an
estimate based on either calculating an average of latitude/longitude coordinates
in a specific postal code (ZIP™ centroid) or by averaging latitude/longitude
coordinates of street segments within the given municipality (city centroid).
As business becomes more
internationalized each year, the demand for geocoding global addresses also
increases. When considering a specific geocoding engine, it's important to
understand that geocoding levels of accuracy for each country are different
from company-to-company. The level of accuracy depends upon the various data
sources the vendor is pulling from. One vendor, for example, may have rooftop
level geocoding for Russia, Australia, and the Czech Republic, while these same
countries may be categorized under a less-accurate level of geocoding at a
different company. You will also find that companies use different names for
their levels of geocoding accuracy: "interpolated rooftop," for
example, versus "address point interpolated."
