Field Navigation Maps

Introduction:

Our focus for class this week was to create a field navigation map. We will be using this map along with a compass to locate specific points in a wooded area known as the Priory in Eau Claire next week.  Working in groups of three, we each created two maps and later narrowed it down to two maps that we liked best. There are certain challenges that arise while making a map—one of which is balancing the amount of information included so that it has the proper amount of information and doesn’t overcrowd it. Another challenge is finding, choosing, and managing the data to suit the purposes of our project. As we went about making our maps, we encountered these issues and were able to work around them to produce useful navigation maps.

Methods:

Obtaining the data:

In order to save time and allow us to focus on the creation of our maps, we were provided data for the priory in a geodatabase created by our professor. The data included two foot contour lines(Figure 2), five meter contour lines (Figure 1), a DEM, outlines of the mapping area, and aerial photographs of the priory. If we were to find this data on our own, it would have been much more complicated. The aerial images came from a USGS seamless server and the five meter contour lines were derived from the DEM also provided by USGS. The two foot contour lines were taken from a University of Wisconsin-Eau Claire survey of the priory shortly after it was purchased by the university.

Figure 1: This is the line feature for the five meter contour lines. I wanted to compare the five meter contour lines and the two foot contour  lines to show the difference in detail. It was used in my final aerial map.

Figure 2: This is the line feature for the two foot contour lines. It is much more detailed  than the five meter contour line and was used in my final elevation map.

Preparing Data in ArcGIS:

Again, we were fortunately provided with the data already formatted for the most part by our professor. However, if were to obtain the raw data, we would have to take several steps before we could work with it in ArcGIS. Firstly, we would have to make sure the data was in a file format that can be used with ESRI products. If we were to create the two foot contour lines for example, we would have had to extract them from the DEM and save them as a separate line feature. Then, we would need to make sure all of the data is in the projection we wanted. We chose to use UTM as our coordinate system as opposed to a geographic coordinate system so as to reduce distortion for our area of interest, the priory, and have map units that can be measured. UTM is much better suited for large scale projects like the one we are working on. The zone for our area is UTM Zone 15 North.

For the most part, we did not have any issues with the projection of the data as on-the-fly projection in ArcMap corrected the differences in coordinate systems (five meter contour lines were in GCS North American 1983, aerial was in NAD 1983 Wisconsin Transverse Mercator, navigation boundary was in NAD 1983 UTM Zone 15 North). The on-the-fly projection uses the coordinate system of the first feature brought into ArcMap and sets each subsequent feature to the same coordinate system so they may be viewed together. We did run into some problems with the two foot contour lines, however, because they had an undefined coordinate system. Therefore, they were unable to be projected using on-the-fly and would not be displayed with the other data. We were able to resolve the issue by starting a new ArcMap session and adding the two foot contour lines immediately after adding the clipped aerial image. In this case, ArcMap was able to use the on-the-fly projection for the two foot contour lines. The layer coordinate system was set to UTM so that the grid had the correct units and all the layers were in the correct context.

Creating the Map:

Once these steps were taken to prepare the data, we were able to start making our maps. Before deciding on making two maps, I tried to make one map including all of the features I thought pertinent (Figure 3). After seeing the result, an extremely congested map, I created two maps each to be used for a slightly different application. My first map was centered on the aerial photograph of the priory (Figure 4). I added the five meter contour lines so as to have a general idea of elevation and a polygon outlining even more specifically the area that we will be working in. I also included a twenty by twenty meter grid to use as a reference. I had previously chosen a ten meter by ten meter grid, but this was unnecessarily small and crowded up the map.  My second map centered on elevation of the area (Figure 5). I used the DEM and the aerial photo, but set the aerial at a fifty percent transparency so that only major features were visible (Compare Figure 6 and Figure 7). I also added the polygon and grid for this map so as to more easily compare specific points with my first map. Each map also includes a scale bar, north arrow, information on sources, and coordinate system information.

Figure 3: This is a map that includes all of the data given to us from our professor to create a field navigation map of the Priory in Eau Claire. As can be seen, this map is very cluttered and difficult to read.

Figure 4: This is one of my final maps for the field navigation project. It  is based on an aerial photograph of the priory.

Figure 5: This is my other final map for the field navigation project. It is based on elevation data of the priory.

Figure 6: This is the DEM I used to make the elevation map in Figure 5 before I  added the aerial photo. It is difficult to ascertain any sort of position on the map and would still be even if a grid were provided.

Figure 7: This is the DEM with an overlay of the aerial photograph of the priory for the field navigation project. It is much easier to locate a position as compared to the DEM in Figure 6.

Final Selection/Results:

For our final maps, my group and I had to decide which maps would best suit our needs in the field next week. In comparing our maps, we noticed that they were very similar and the selection came down to very fine details because each map included the same features in the same format.. For our aerial map, we chose another group member’s because it was cartographically pleasing (Figure 8).  For the elevation map, we chose the one I created simply because it had the aerial overlay to more easily compare maps (Figure 5).

Figure 8: This is the final aerial map created by my group member Kory Dercks for our field navigation project.

Conclusion:

Through the creation of our maps, we learned that there is quite a bit of work that goes into creating an accurate and efficient map. Collecting data can be complicated as it can come from many different sources and formats. Projecting the data is another very important element in making a map, as we learned after encountering issues with the two foot contour lines. Lastly, it is vital that the map has a sufficient amount of data without overcrowding the map. It must be easy to read while still including all the information necessary for the map reader. We will be testing the two maps our group chose as we navigate the priory next week.