Monday, March 3, 2014

Activity #5: Creating a Field Navigation Map

Introduction

Later in the semester, when weather conditions are more hospitable, our class will be going to The Priory for an activity involving navigation by map and compass. For that exercise, we will be using navigation maps that we created during this current activity. Our professor provided us with several different data sets that we could use, though we didn't have to use them all. With this data, we were to create two maps: one using a Universal Transverse Mercator (UTM) projection, and one using a Geographic Coordinate System (GCS) using decimal degrees.

Methods

Pace Count

Before we started making the maps, we found our 'pace count.' Pace count is the number of steps an individual takes within a set distance, in this case 100 meters. As a class, we went outside and marked 100 meters using a laser range finder. To find our pace count, we simply walked the 100 meters and counted every other step (I counted only when my left foot hit the ground). I did this twice and came up with a pace count of 66 the first time and 67 the second time.

Knowing our pace count will come in useful when we eventually do our map and compass navigation. While at The Priory, we will be able to measure distance on our navigation map, then be able to estimate how far we travel by counting our steps. When we found our pace count, we were walking on a flat sidewalk with no obstructions. This won't be the case when out in the woods, meaning our pace count will be higher. We'll have to take that into consideration while navigating.

Map Creation

To create the maps, the class was given access to many different data sets. It is important to avoid the temptation to put all the data on the map, however. Though it seems that more data would be better, in this case the map could be too cluttered. Since we are using these for navigation, we want to be able to see our grid and contour lines more than anything else.

For the first map, I chose to use a Wisconsin UTM projection with a grid system based on meters (each grid line at 50m). This would make navigation easier because my pace count is based on 100 m distance. I also wanted to keep this map more simple for navigation purposes. Figure 1 shows the 2 ft contour line data set, and Figure 2 shows the same data but with our navigation boundaries overlaid on top. The red box is the extent of where our points will be located, so all of our navigation will be concentrated there. Figure 3 shows the 5 ft contour lines. As you can see, this data is only available to the extent of the black box, which is a shapefile created by our professor to show a maximum extent of our study area.
Figure 1 - 2 ft contour line elevation data for Priory

Figure 2 - 2 ft contour line elevation data with navigation
boundary and point boundary boxes

Figure 3 - 5 ft contour lines within navigation boundary
For the second map, I used an unprojected coordinate system using the Geographic Coordinate System of decimal degrees (GCS NAD 1983 2011). The grid system than was also displayed in decimal degrees. I set the interval to .001 degrees on both the x and y axis. I also used a satellite image of the Priory (Figure 4) as well as a DEM (digital elevation model) (Figure 5) in this map, neither of which I used in the first map. This time I left out 2 ft contour lines and just used the 5 ft contour lines (Figure 3) to avoid the map getting too cluttered.
Figure 4 - Satellite image of part of Eau Claire. Black box
shows our study area.

Figure 5 - DEM of part of Western Wisconsin. Black box
shows our study area.

 Results

My first map, the one using a UTM projection, is shown in Figure 6. This map contains 2 ft and 5 ft contour lines. I labeled the 5 ft contour lines so there was some reference. Figure 7 is the second map I created that is using the Geographic Coordinate System in decimal degrees. As I mentioned earlier, I added satellite imagery as well as DEM data colorized showing higher elevations in green, and lower elevations in red.
Figure 6 - Navigation map of The Priory featuring 2 and 5 ft
contour lines using a UTM projection and grid system every
50 ft.

Figure 7 - Priory map featuring 5 ft contour lines using a GCS
coordinate system and a grid system in decimal degrees
every .001 degrees.

Discussion

The first map I made I think will work best for navigation. I used both 2 ft and 5 ft contour lines with no other data sets so that I could see detail in the terrain with out making the map too cluttered. Since this map uses a grid system in meters, it will be easier to use my pace count to judge distance. The second map will be more for reference. That map has more visual data, so that if we end up off course we can find a land mark and get our bearings. Since this one uses decimal degrees, it would be more difficult to actually navigate by because distance would not be as easy to calculate.

Conclusion

I am really looking forward to using our navigation maps in the field. Typically, this activity would be followed by the activity where we actually go to the Priory, but because there is still a great deal of snow on the ground and still very cold, we are putting that exercise off until later in the semester. As a geography student, I have made many maps. This is the first one that I will put to use and have to depend on, so I am eager to test it out.

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