Assignment 4: Navigation Maps

Introduction

For this assignment, the goal was to produce two maps of an area *three miles* south of the UW - Eau Claire campus; the Priory residence hall. In a later lab, student groups will have to navigate their way through the Priory's forest using only the GPS points of the route and their maps. 

To start with a bit of background knowledge on coordinate systems was an important part of creating these maps (see Results section). Coordinate systems are a common tool used for navigation in coordination with others such as Global Positioning System (GPS) units. Since the Earth is 3-D and maps are usually 2-D, such as the ones created for this assignment, these coordinate systems endure distortion when making the transformation- the projected coordinate system attempts to minimize that distortion. The two coordinate systems used for these maps are the unprojected geographic coordinate system (GCS), and a projected coordinate system (PCS), the Universal Transverse Mercator (UTM). 

Figure 1: Geographic Coordinate System (Environmental Research Institute, 2016).

The GCS was the coordinate system used to make the first map for this assignment. This coordinate system is based on degrees of latitude and longitude originating from the center of the Earth (see figure 1). The intersection of the prime meridian and equator serves as the central axis for this system. The degrees can be written in decimal degrees or degrees minutes seconds, both of which will be used in the future navigation lab in coordination with GPS coordinates.

Figure 2: Transverse Mercator Projection (GIS Geography, 2017).

Figure 3: UTM zones (GIS Geography, 2017).

The PCS used to make the second map for this assignment was the UTM. This PCS is a cylindrical projection that divides the Earth into 60 zones (figures 2 and 3). On a local level (mapping within one zone), this projection minimizes distortion of surface features better than the GCS.

Methods

Once the two coordinate systems used for this lab were conceptualized, those concepts were used to make two navigation maps in ArcMap. For this assignment, the students were given a few different data files to choose from: a USGS topographic map, some aerial imagery covering the land surrounding the Priory, some LiDAR digital elevation models (DEMs), a two foot contour line shapefile, and the navigation boundary. Since the class will be traversing some varying terrain, I felt it was important to include the layers that would show me the variations in terrain, so I chose to use the DEMs and the USGS topographic map for a layered hillshade.

To produce these maps, I started by bringing in the Navigation Boundary layer, USGS Topographic Map raster, and the LiDAR DEM rasters to a blank ArcMap document (figure 4). 

Figure 4: Layers used to produce both maps.

Once this was done, ensuring that the coordinate systems of each layer were either the GCS or UTM coordinate systems uniformly was the next step. I began with the UTM map. To do this, the coordinate system was established in the data frame properties, then each layer was projected to the correct coordinate system (if it wasn't already). 

• First, right-click Layers in the table of contents window and click on Properties. This will take you to the data frame properties window. From there click on the Coordinate System tab and ensure that the coordinate system is checked to NAD_1983_UTM_Zone_15N.  
• Next, right click on each of the layers shown in Figure 4 and go to their Layer Properties to determine if they need to be projected. This information can be found in the Source tab (figure 5).

Figure 5: Layer Properties window displaying that the layer is already projected in the correct coordinate system.

• If a layer has a different coordinate system than the one highlighted in Figure 5, then it needs to be projected. To do this search for the Project tool (if shapefile) or Project Raster tool (if raster file) in the search window or toolbox window of ArcMap. 

Figure 6: Project tool window.

• A popup window will open (figure 6). Set the input raster, output raster location and name, and appropriate coordinate system. Do this for all subsequent rasters and shapefiles. 
•  One trick for this is to import the coordinate system from a layer known to have the appropriate coordinate system (figure 7).

Figure 7: Add coordinate system from layer with known coordinate system.

After all of the layers were converted to the same coordinate system, the layered hillshade was created. This was done by first organizing the layers correctly: 

• First, ensure that the Navigation Boundary layer is listed at the top of the drawing order, then the USGS Topo layer, then the DEM layers. 
• Next, set the Transparency property of the USGS Topo layer to 70% in the Layer Properties window, under the Display tab (figure 8). 

Figure 8: Set transparency of USGS Topo layer.

• Then, check the Use hillshade effect box in each of the DEM Layer Properties' (figure 9).

Figure 9: Check the Use hillshade effect box for DEM layer properties.

Upon creating the layered hillshade, the map was made by switching from Data View to Layout View. From there, the following were added to the map:

• North arrow
• Scale bar
• Projection, coordinate system, author, and data source information
• Labeled grid

To create the second map using the GCS, just repeat the above steps, but with the GCS instead of the UTM coordinate system. 

Results

Figure 10: Navigation map using UTM projection.

Figure 11: Navigation map using GCS.

Discussion

The purpose of these maps are to provide the student with resources that will be used to aid their navigation through the navigation area. While many other students used the 2 ft contour shapefile with the Eau Claire imagery underneath, I felt as though I wouldn't be able to use that information effectively in the field. Knowing a bit about myself and the nature of this activity, I figured really getting a sense of variations in the landscape would help me to be most effective in navigating my way through the upcoming lab. Having once upon a time striven for a geology minor, the spatial recognition of physical landscape and terrain features resonates with me more so than surface features and the busy 2 ft contour lines. Hopefully using the data I did will prove to help me effectively work through this lab. 

Looking at the resulting maps (figures 10 and 11), I feel as though the UTM map (figure 10) will be more effective to use instead of the GCS map (figure 11). With the 50 meter scale and less distorted projection of figure 10, it will aide in more accurate navigation than figure 11, which is distorted and has a larger grid scale- creating more room for error.