Lab 5: Development of a Field Navigation Map

Introduction:

Many activities are conducted in the field, from complicated things like surveying, and all the variations that come with that, to even the most basic, like recording data. But one thing that is unavoidable is the need to navigate through the terrain. To do this effectively, one needs the actual tools for navigation, be something like a compass, or even an advanced GPS unit. Additionally, the navigator needs to be able to know where they are in relation to other things in the area. This can be done by the use of a standardized grid system, where each grid section is an equal distance, like a coordinate system grid. For this lab, we were required to create a map to be used in the following week for navigation at the Priory, a wooded area just outside of the city of Eau Claire, WI.

Methodology:

The first step in creating an accurate field navigation map is to determine a sort of standardized distance marker. Since the terrain at the Priory is going to be varied, bringing a long measuring tape would be impractical and time consuming. Instead, a pace count was recorded for 100 meters. To do this, a 100 meter section was measured, and then the number of paces per person was recorded. In the navigation of the Priory, the person with the most consistent pace should be the distance walker, to ensure that the distance covered can be easily measured.
Once this step was completed, the design of the actual map itself was next. A number of images of the City of Eau Claire could be selected as a base layer of the map, to get a reference point before starting to navigate the terrain. An aerial image of Eau Claire West, the Southeast quadrant, as well as several raster images of the areas surrounding the Priory, were all obtained through the WROC_Specs PDF file in a data folder that we were provided with prior to map design. Contour lines were also provided for us, at two foot and five meter increments. The two foot, a significantly higher degree of detailed lines, were provided through a University of Wisconsin - Eau Claire survey that was provided to the institution when they purchased the Priory, and the land surrounding it. The five meter contour lines were retrieved from a 1/3 arc second DEM  obtained from the USGS seamless server, which was also where a topographic map scanned into ArcMap for use in this project, a .DRG, was retrieved from.
Like any project involving field methods, problems arose that needed to be addressed. The main one was an issue with the coordinate systems not matching up between the aerial photos, raster data sets, topographic maps and lines, and the contour lines. The two foot contour lines, a .DWG file, is originally an AutoCAD file, not a shapefile or feature class. This means that the projection will not always allow the lines to show up on the map, when laid over the rasters. This happened because the projections of the different images and basemaps were not the same, and thus would not line up with one another. The Project tool needed to be used in order to have all of the components of the map in the same projection, which was decided to be the North American Datum (NAD) 1983 Universal Transverse Mercator (UTM) Zone 15N section, which is one of the most accurate projections for the Eau Claire area. Initially, the files were imported into ArcMap through the Project on the Fly feature, which tries to line up the data in the same projection system. But in then end, that feature did not accurately do its job, and all of the components needed to be projected in the same system.
Once this was taken care of, however, the actual map design went smoothly. A few map options were available. Initially, I thought that using the topographic map provided in the geodatabase, as illustrated in Figure 1, would provide a sufficient map for the activity. However, the lack of aerial imagery did not show a good reference point for the user. Our group each made a map of their own, with Figure 2 showing the map that I created, and in the end, the map shown below in Figure 3 was the one that we decided to use. We chose the five meter contour lines, instead of the two foot ones, just because of the ease of importation and consideration of navigation next week. If the contour lines conflicted with the rest of the data, navigation of the Priory would be considerably more difficult. The .DWG file was causing too much of an issue, and we decided, for simplicity's sake, to use the five meter ones. Additionally, we used the aerial image of Eau Claire West, the Southeast quadrant as a reference layer, deciding on the color image over the black and white raster files.


Figure 1: Topographic map made using the data provided in the geodatabase for the project. The map proved to be confusing and was decided not to be used, for lack of a good reference area.




Figure 2: The field navigation map that I created for use at the Priory next week.

Figure 3: Navigation map adopted by our group for navigation of the Priory next week.

 Discussion:

The most difficult part of the design of the navigation map was by far the issue involving the coordinate system differences in the data provided. The Project on the Fly feature of ArcMap is extremely useful, but it also spoils the operator by getting them into the habit of not actually projecting each piece of data imported to ensure that it matches the data frame's coordinate system. Between the raster data sets, topographic maps, .DWG files, and point and navigation boundaries, three separate coordinate systems were used. If any one part of the map was not in the same coordinate system, navigation would be considerably more difficult, if not impossible. Problems will likely arise when actual utilization of the map occurs in the field, but it was certainly beneficial to have these addressed and taken care of prior to going into the field, just so that will be one less thing to account for at the Priory.

Conclusion:

While not being as labor intensive as other laboratory sessions, this week's project was no more important in the education of geospatial field methods. Having to deal with the issue of projections and coordinate systems may have been frustrating, but overcoming those problems provided a valuable educational experience by forcing us to take all of the factors into account prior to actually going out in the field to test out the maps that our groups had made. Addressing these issues now, as opposed to trying to compensate for them while out in the field makes sense, and prevents further hassles that our groups would no doubt have to account for while trying to navigate an area with a map that has conflicting features in different coordinate systems.