Geocoding Techniques and Uses

Posted by dunitzsantrino on January 10th, 2015

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."

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