Discrete Georeferencing (016)

Instructor's Notes

 
The lesson on discrete georeferencing was developed largely from the perspective US postal code system and the Bureau of the Census TIGER files.  However, some of the examples do use the city of Columbia parcel level file.  The parcel level geocoding or single address method can be used anywhere in the world - all that is required is that you have a set of addresses associated with a set of X, Y locations.  Therefore, the concepts should be rather universal.  From a web browser you can do a lot of the examples using the Palmetto Seafood company as an example.  But you could just as easily find another address in an other city.  Maybe a book publisher or 1600 Pennsylvania Av, Washington DC

There are several ways that you could use the materials.  If you have geocoding software you should be able to set up the TIGER data for your area and develop a set of exercises or examples.  I like to emphasize that most geocoding is based on interpolation.  The Census works on the basis of potential address range - i.e. the 100 block goes from 101 - 199, and 100 - 198 even though the actual addresses on a street rarely exceed 50% of that range.  Therefore the interpolation process can only get you so close and it is easily to demonstrate.  It is also important to note that if you end up locating an address on the basis of the center of its five digit zip code you can be very far (several miles) from the actual location.

If you have access to a GPS system you could build a point level geocoding base and geocode using a single address procedure.

If you do not have geocoding software then you can do the entire lesson with a web browser. Except that you will not create the actual GIS data base.  I particularly like http://MapsOnUS.com for locating a single address.  The students could select a number of addresses along the same street and see how the interpolation system works.  The postal service zip+4 locator is also informative.

http://bigbook.com is a good way to select and locate a series of businesses in a city.  It is a useful way to teach some economic geography by comparing automobile dealerships that tend to cluster versus grocery stores that are more dispersed.

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