GIS II: Lab 2, Georeferencing

Goals and Background:

The goal of this lab is to review the process of georeferencing using ArcGIS software. This will be done using the ESRI georeferencing course and data as well as data from the University of Wisconsin-Eau Claire. 

Methods

For the historical Eau Claire map, the Mcenterlines shapefile is added first and has a projected coordinate system of NAD_1983_HARN_Adj_WI,_EauClaire_feet and a projection of Lambert_conformal_conic. The historical map has no an undefined coordinate system and projection. This means that the Mcenterlines shapefile is the referenced data for the historical crop. 

For both of this data, the georeferencing toolbar is used. To make creating links easier, a side by side screen is used as seen in Figure 1 below. 

Figure 1. Side-by-side view of the historical, undefined Eau Claire map (right) and the georeferenced Mcenterlines map (left). The study area is consistent between the two maps.

Results

Figure 2. Historical map of Eau Claire, WI overlaying the modern Mcenterlines shapefile (in green). The historical map is at 50% transparency. Note the change in water features, ward boundaries, and street names. Historical maps, like this one, are often drawn in an obsolete local grid system and are not very accurate. There was also issues with georeferencing the historical map and getting it as close to the modern basemap and Mcenterlines files as possible.

Figure 3. Comparisons of the water features in the Eau Claire, WI area. The purple outlined area represents the location of water features today and the light blue represents the location of water features in 1878. Some of these changes could be anthropologically caused while some may be naturally caused. Anthropogenic causes include dams, bridges, and flood barriers to name a few.

Sources

All data came from ESRI and the University of Wisconsin-Eau Claire.