Week 12 - Network Analysis, Geocoding, & ModelBuilder

This week we covered some pretty dense topics:

Geocoding

What is geocoding? Geocoding is the process of transforming a description of a location--such as a pair of coordinates or an address--to a location on earth's surface (Esri 1995-2013). In our lab assignment, we learned how to create an address locator in ArcGIS, then conducted geocoding by address matching, and finally matched unmatched addresses using the Interactive Rematch window interface. I found the re-matching section to be extremely valuable because the Interactive Rematch window isn't very intuitive, but our lab instructions were so awesomely written providing me the tools and knowledge to follow through and successfully execute the assignment goals. This exercise also emphasized the importance of data accuracy, as the old mantra goes, "garbage in, garbage out". Unfortunately, as GIS practicioners conducting analysis, we may not always be in control of the data that may be provided to us, and if it requires geocoding poor and inaccurate data, then it will result in poor geocoded matches. As a rule of thumb, the unmatched rate should be 5% or less.

Network Analysis

A network is a system of interconnected lines and intersections that represent possible routes from one location to another (Jensen & Jensen 2013). Thus, 'network analysis' means examining these networks, leading to new insights to address very important problems. When we think of networks, we automatically think of transportation (cars and other vehicles getting from one place to another), but networks go way beyond this--in fact, networks are both natural and man-made. Some examples include: airplanes on flight paths, bicycle trails at parks, animal voyages to and fro nesting habitats, goods and resources traveling on trains/railroad systems, the flow of water and sewage, oil in pipelines, electric utilities, and more (amazing!). So why has GIS been so immersed in these networks? Well, we (humans) have always been intrigued in identifying the optimum route within these networks. In our lecture we covered undirected and directed networks, network costs, impedances, barriers, service areas, location-allocation modeling, and the National Hydrography Dataset (NHD).

For our lab assignment, we learned how to utilize ArcGIS's Network Analyst Extension to create a small map output of an optimal route involving 3 stops at 3 different Emergency Medical Services (EMS) stations in Lake County, FL. We got familiarized using the analysis layer in the Table of Contents, Location Snap Options settings, the Create Network Location Tool, configuring parameters under the Analysis Settings window, the Solve button, and the Directions Window.

ModelBuilder

ModelBuilder is a visual programming language used to build workflows; these workflows (or models) string together sequences of geoprocessing tools, feeding the output of one tool into another (Esri 1995-2013). During this week's lecture, we got an introduction to ModelBuilder by completing an exercise via Esri's Web Course entitled, "Building Models for GIS Analysis Using ArcGIS". In the exercise, we examined a gas utility model that was already built and answered questions about it. The purpose of this exercise was to understand how this model was put together, which can help us in the future when building our own. The power of ModelBuilder lies in designing and creating a reusable and shareable workflow which can maximize productivity by more effectively and efficiently automating tasks. We will be covering ModelBuilder more in-depth next semester in the GIS Programming class.