Creation of a Field Navigation Map Activity

Introduction

          This lab acted as a preliminary for a field activity in a few weeks at the Priory. Priory Hall is a UW - Eau Claire off-campus residence hall that is almost surrounded steep, forested slopes. To prepare for that upcoming field outing, we were tasked to create two field navigation maps with different coordinate systems.

          Coordinate systems are a key tool for navigation. Along with navigation tools, like the modern GPS unit, a reference system is needed in order to place geographic features and locations spatially and to navigate them.

          The two coordinate systems that we will focus on for this activity are the geographic coordinate system and the Universal Transverse Mercator (UTM) coordinate system.

          The geographic coordinate system uses a 3-D model of the earth and latitude and longitude - angular measures that originate from the center of the model to define locations (Figure 1). The values generated by latitude and longitude are often written as decimal degrees or degrees-minutes-seconds. The prime meridian is defined as 0 degrees longitude with the other lines of longitude, or meridians, ranging to -180 degrees to the west and +180 degrees to the ease. The equator acts as 0 degrees latitude with additional lines of latitude, or parallels, ranging to -90 degrees to the south and +90 degrees to the north. Since latitude and longitude are not uniform units of measure due to the shape of the earth, great distortion of the land area, especially towards the poles, occurs when displaying the geographic coordinate system in a 2-D format, like a paper map or ArcMap (Esri; Esri, 2016).

Figure 1: Geographic coordinate system showing how latitude and longitude locates a point on the model.

                    The second coordinate system we worked with was the UTM coordinate system. The UTM coordinate system is based on the Transverse Mercator, a cylindrical projection (Figure 2) Projections are the transformation of the earth's shape into a 2-D plane (Esri). In UTM, the globe is divided into 60 zones, each 6 degrees of longitude long (Figure 3). Each zone contains a central meridian where there is the least distortion (Esri, 2017).

 Figure 2: The cylindrical projection of the Transverse Mercator  (GISGeography, 2017).

Figure 3: The 60 zones of the UTM coordinate system  (GISGeography, 2017).

          

Methods

          Before beginning creating our navigation map, we evaluated the raster data and shapeless provided for us by our professor. This included three LiDar images that made up our study area and the surrounding area. We also had colored and black-and-white imagery of the south-eaters part of Eau Claire. A scanned image of a USGS standard series topographic map of Eau Claire was available for use. Two shape files included 2-ft. contour lines and the boundary line of our study area.

          Evaluating the data, we saw that one of the files didn't have a defined projection. It is crucial that the data have a projection labeled and correctly. If not, you could ruin your data and whatever you intend to use it for. To name the projection, we used the Define Projection tool, located in Data Management-Projections and Transformations tab (Figure 4).

Figure 4: Define Projection tool.

          Once that was completed we needed to decide what data we wanted to use for our map. I decided on the color image of South-East Eau Claire, the study area boundary, and the 2-ft, contour lines. Good practice would have us project our selected data into one projection and not rely on on-the-fly projection. The Project Raster tool in the Data Management-Projections and Transformations-Raster tabs is used to change the projection of my raster data (Figure 5). I used the NAD 1983 UTM Zone 15N coordinate system of the Transverse Mercator projection as my UTM map and GCS WGS 1984 coordinate system for my geographic map. Each data set that I used was projected once for each coordinate system.

Figure 5: Project Raster tool.

          However, not all the data I chose is raster data. For vector data, use the Project tool in the Data Management-Projections and Transformations tab to change the projection of the boundary and contour data (Figure 6).

Figure 6: Project tool.

          To clean up the layers a little bit, I used the Clip tool in the Analysis Tools/Extract tab to clip the 2-ft. contours within the study area boundary (Figure 7).

Figure 7: Clip tool.

          For each map, I set the image raster to display a 30% transparency so the data doesn't look too busy. Then I displayed the boundary and 2-ft. contour layers on top of the image. In layout view, I went to data frame properties to set up the grids for my maps. For the geographic coordinate system map, a graticule grid is the appropriate choice. Intervals were set for 5 seconds and labels were in decimal degrees. For the UTM map, a measured grid is best for knowing how far your moving in the field. Intervals were set at 50 meters. Labels were customized as mix font, 5 font size, no decimals, and to the left of the tick marks.

Results

          The UTM map (Figure 8) and the GCS map (Figure 9) all contain the same elements to complete each map: a north arrow, a scale bar, a RF scale, coordinate and/or projection name, grid, background, data source, and a watermark with my name.

          It important in map making that you don't overcrowd your map and keep it balanced. Giving the background image a 30% transparency kept the map from looking too busy. The boundary layer was given a bright color to distinguish it from the background and contour lines. Lastly, the contour lines were given a more pastel color so the layer pops out but doesn't become overwhelming.        

Figure 8: Navigation map of the Priory with a UTM Zone 15N projection and a UTM grid spaced by 50 meters

Figure 9: Navigation map of the Priory in a WGS 1984 geographic coordinate system with a grid in coordinate decimal degrees.

Conclusion

          I chose my data because I felt it would help with our navigation the best. The boundary line was needed to show us the extent of our study area. The 2-ft. contour lines give us a good idea of the elevation of the area. The colored image of Eau Claire would assist us in distinguishing different features like buildings, lawns, forests, and fields. I felt that the scanned image of the topographic map was too busy for in the field. The Lidar images could've added elevation information, but I thought that the contour lines were sufficient enough and complemented the colored image background, which offered useful information for navigating.

          If you look at a map of the UTM zones, you'll see that Eau Claire is in Zone 15N. That is why I chose NAD 1983 UTM Zone 15N as the coordinate system to project my UTM data in. For the GCS map, I chose the GCS WGS 1984 one of the most recent and widely used geographic coordinate systems.

          I predict that the UTM map will be the most helpful in navigating the study area. Distance is easier to measure with the UTM measured grid. In addition, the final map looks less stretched out than the GCS map, especially given the information we now know about geographic coordinate systems. Though, I wonder if the GCS map would be more useful in figuring out our location with a GPS given its grid is in decimal degrees. We'll have to wait and see until the field activity at the Priory.

Sources

Esri. (n.d.). Coordinate systems, map projections, and geographic (datum) transformations . Retrieved October 16, 2017, from Esri Resources: http://resources.esri.com/help/9.3/arcgisengine/dotnet/89b720a5-7339-44b0-8b58-0f5bf2843393.htm

Esri. (2017). Universal Transverse Mercator. Retrieved October 16, 2017, from ArcGIS Desktop: http://desktop.arcgis.com/en/arcmap/latest/map/projections/universal-transverse-mercator.htm

Esri. (2016). What are geographic coordinate systems? Retrieved October 16, 2017, from ArcGIS For Desktop: http://desktop.arcgis.com/en/arcmap/10.3/guide-books/map-projections/about-geographic-coordinate-systems.htm

GISGeography. (2017, September 2). How Universal Transverse Mercator (UTM) Works . Retrieved October 16, 2017, from GISGeography.