Assignment 5: Creation of Topographic Map for Land Navigation Exercise

Introduction

This week's assignment was to create a topographical map, using a UTM coordinate system, to be used for land navigation. This report, along with the next couple will not be held to as high of standard, as there will be a fully encompassing report at the end of the land navigation exercises.

The purpose of the land navigation exercises is to learn how to navigate in the natural environment without the use of technology (such as GPS), as current technology relies on batteries to operate, which can be expended, leaving you stranded unless you have other means of finding your way about.

The location of the land navigation exercise is The Priory, a 112-acre mostly wooded area that was a monastery, but was purchased by UWEC in 2011 and converted to a Childcare Center.

Method

The first step we had to accomplish was establishing a pace count. This is necessary for having a semi-accurate idea of how far you are traveling from one location to another when not using high-tech equipment. To do this we measured out a 100 meter distance using our distance surveyor like we used last week, and then counted the number of paces it took us to travel that 100 meter distance. A pace is started from a stand-still and you lead with your left foot, counting with every step of your right foot. Each student did this three or four times to determine their average. My average pace was 64 per 100 meters. This pace count, however, will not be quite as accurate in the field due to the fact that this was on level terrain. Once we are at the Priory, the varied terrain and snow will cause our numbers to increase.

Next, we went into the lab to begin making our maps. The professor provided all of the data we needed to make our map. The data consisted of: a navigational boundary of the Priory, a point boundary which is where the points we will have to locate will be in, 5 meter contour lines, a 2-foot contour DWG file (CAD file), and aerial photographs of the area. The DWG files were obtained in a UWEC survey upon acquisition of the land. The 5 meter contour was created from a 1/3 arc second DEM, which was downloaded from the USGS seamless server. The aerial photographs were obtained from the Wisconsin Regional Orthophotography Consortium (WROC). With all the data provided, we were allowed to choose what we wanted to use.

In order to use all of the data effectively, it is important to ensure all of the data is in the same projection. This is sometimes easy to forget in ArcGIS 10.1, as data is projected on-the-fly. Though this is nice at times, if you forget to check and start running analyses with on-the-fly projections, you can quickly run into errors. Having all of your data in the same coordinate system is vital to the usefulness and accuracy of your maps. While most people are aware of the latitude/longitude coordinate systems, these cannot be used effectively to measure distances between points as their units of measurement are degrees. In order to measure distance, you need a coordinate system that is measured in meters or feet. Being in Wisconsin, we essentially had three useful options: UTM, State system, and State Plane system. In Wisconsin, the state is split between UTM Zone 15 and 16, but Eau Claire is well within Zone 15. State systems and State Plane systems provide greater accuracy in a small area, and are especially good for areas that are near the edge or between two UTM zones. We used UTM Zone 15N with NAD83 datum reference.

With the projection decided, it was time to either ensure the data was already UTM Zone 15N, or project it using the Project tool. It is very important to not confuse Project with Define Projection. Define Projection merely overwrites the coordinate system information, and is intended to be used on datasets that have either unknown or an incorrect coordinate system define. In order to actually convert a dataset from one coordinate system to another, the Project tool must be used. An issue arose with our 2ft contour file, which was a DWG (CAD file). This dataset had an unknown coordinate system, but was unable to have a projection defined. In order to properly load the file we had to add our projected orthoimage first, which set the data frame projection to UTM Zone 15N. In ArcMap 10.1, this means that any further layers are projected on the fly to UTM Zone 15N. As discussed earlier, this is not the ideal method to use, but for what we are doing it will work.

With all of the datasets in the proper projection, it was time to create maps to be used next week in the field. Each of us in the group needed to create at least one map, which we would discuss with our group and decide on which one we wanted to be printed out for use. Both of my maps used the 2-foot contour to provide us with the best idea of what the terrain was like. Figures 1 and 2 show my maps, with Figure 1 having the orthoimage as the bottom layer to show the environment.

Figure 1: Map of the area of interest, using the orthoimage of the area as the bottom layer. The 2-foot
contour lines are used to provide elevation.  A grid system with UTM coordinates overlay the map
to provide a way to navigate the area.

Figure 2: Map of the area of interest, with only the 2-foot contour lines for elevation.  The exlusion
of the orthoimage is intended to provide a simpler map that will be easier to read.  This map also
contains a grid system with UTM coordinates in order to navigate the area.

Discussion

After completing my maps, it was time to meet with the group and decide which maps we wanted to use. We decided on using Joel's maps, as we all liked his use of the colored DEM to show elevation (Figure 3). His second map was also simple and clear, using just the 2-meter and 5-meter contours to show elevation (Figure 4).

Figure 3: Joel's first map that uses a transparent, color-coded DEM to show elevation, and the
orthoimage underneath to assist in visual referencing.

Figure 4: Joel's second map contains 2-meter and 5-meter contours for elevation, and
also shows the location of buildings and the pond.  A grid system with UTM coordinates
is also provided for navigation.

Conclusion

This assignment demonstrated the importance and necessity of ensuring all datasets being used are in the same coordinate system. At the same time it showed the malleability of cartography, which was seen in the differences in the maps each group member made. While the data being used follows strict guidelines, the map itself is a creative endeavor that can have many useful results.