Geocoding Addresses

Another form of analysis that Cartographica performs is Geocoding, or GEOgraphic enCODING of data that is not native GIS data. Although similar in some ways to the process of importing other data, there are two special kinds of data we will treat separately: addresses and photos.

Cartographica has two distinct, and powerful, address geocoding capabilities. Prior to version 1.2, Cartographica provided geocoding based on address information that was already in the map. This was usually street information received from a government agency or a data provider. More recent versions of Cartographica have also added the ability to geocode using Bing Maps geocoding services. This service provides high-quality, constantly-updated geocoding capabilities for addresses in a large area of the world. Although it is easier to set up, there are reasons why you might not want to use it for geocoding. Some of these reasons include: historical geocoding, where the data that you are geocoding uses streets that no longer exist or have been realigned since the time of the original data collection.

The Bing Geocoder is available to users who have active maintenance or active subscription products. If your Cartographica license is a perpetual license and you need access to the Bing Geocoder, you will need to have an active maintenance plan.

Bing Geocoding

Using the Bing geocoder removes most of the configuration headache from the process of geocoding. In many cases, it is more up-to-date than files that you can obtain about the area that you are geocoding and it is certainly easier to configure.

Configuring Bing Geocoder
  1. Choose  Tools > Geocoder Options…  
  2. Select  Bing Geocoder tab and click  OK.
    You are now ready to use the geocoder in this map.

Internal Geocoding

Geocoding is a complex function and requires all the right data be in place to do it well. Cartographica has a powerful Geocoding capability, but to use it, you must gather data first. Most data is accurate to the last census update and may be more recent, based on the government's move to modernize and increase accuracy in the data or your commercial source. Keep in mind that if you are trying to geocode an old address, your accuracy may suffer if the data is too new, since some street realignments, renaming, renumbering, and removals may have changed the landscape since the address data was taken.

In comparison to Bing geocoding, the Internal geocoding is much more strict in terms of how it interprets data. So, you should expect to use highly regularized data to match the TIGER/Line files; for example, "100 A St SE" in DC will not match "100 A St" using Tiger/Line data.

First, you need to figure out the area of your search. Generally speaking, you want to limit geocoding to a limited number of counties, to reduce the amount of work necessary on your computer. However, if you must do a large area, or if your area is undefined, there are geocoding services that can do bulk geocoding for a small fee.

Preparing to geocode with TIGER data
  1. Locate the TIGER files on the Census Bureau web site. First, go to the TIGER/Line Shapefiles page, then select the particular year you're interested in. To use these files, you will need at least the Edges layer for the area that you're working with.
  2. Locate the appropriate files on the server and download the state, county or counties that you are interested in using for geocoding. After unzipping the files, choose File > Import Vector Data… and then select the edges .shp file for import. This will import the edge data for that area.
  3. If you need to geocode more than one census area, you may either merge the two layers into a single layer and use the new layer as the geocoding layer, or to run the geocoder twice, once with each layer selected.
  4. The next step is to configure the geocoder. Choose  Tools > Geocoder Options…. If you are using standard TIGER/Line or Shapefiles, Cartographica should set up the geocoder automatically. In most cases, not only is the layer determined, but the field names are chosen as well. If you are using a file from a different source, or of a different vintage, you may need to set up the individual field names. At a minimum, Cartographica requires: Numbers From and Numbers To (for either side of the street or both), the Street Name, and Street Type (Rd, Ave, etc.). Each of the other entries (prefix and suffix, zip codes, state, and city) are optional but will increase the accuracy. In the case of City or State, you may type in value to match the City or State section of the address.
    However, it is not a requirement to use TIGER files for geocoding. The need is to have a minimum set of parameterized lines. Any line layer can be selected as the Geocoding layer.
Configuring Internal Geocoding
  1. Choose Tools > Geocoder Options.
    The  Geocoder Options window appears.

    Geocoder Options Window
  2. From the  Geocode using layer menu, select the layer that has the attributed lines in it.
  3. Each of the geocoding fields in this dialog provides a more specific way to find the data.
    For each field in the geocoding layer that you want to match to addresses, select an appropriate Geocoding Fields entry and choose the corresponding field. Generally, the more fields that you use, the more precise the geocoding will be. However, there are times when avoiding certain data fields is appropriate due to inaccurate data or the format of the original addresses.
    The most important features are  Street Name Street Type (ave, rd, street, etc.) and Numbers From and  Numbers To on the right and left sides of the street (indicated by the left and right columns). If you have these at a minimum, your data will probably geocode pretty well.
    If you have  Zip Codes for the left and right sides, those can help make things noticeably faster when working with large sets of lines.
  4. If you have data for only one state and the data does not contain a state column, type in the state abbreviation in the State field to automatically exclude any addresses not in that state.
  5. Once you have selected all of the geocoding options, click  OK.
    Now that you have set up geocoding, you can use it for the  File > Import Tabular Data… or  File > Acquire Database Data… features. Each of these have options to read the data as addresses and then geocode them.

Geocoding vCards

As an easy demonstration of Cartographica's geocoding abilities, you can geocode vCards (or addresses dragged from the Address Book).

Geocoding your address book
  1. Set up the Geocoder options properly.
  2. Drag any vCard onto a Map window
    A new layer named  Geocoded will be created with the address(es) from the vCard(s) you have copied.