Field Navigation Part One

Construction of a map for use in field navigation.

Introduction:

For the next two weeks we are working on one project, Field Navigation. This project has been split into two smaller projects; the first is to create a map for use in the actual field navigation exercise, and the second is to use the map to navigate a plot of land and locate several items along the way. The plot of land we will be navigating is known as the Priory. The Priory is located approximately 5 kilometers south of the University of Wisconsin Eau Claire (UWEC) campus on Priory Road. Directions to the Priory from UWEC are as follows. From the main campus area take Roosevelt Avenue east to State Street, turn right on State Street and follow it south until you come to Lowes Creek Road, turn right on West Lowes Creek Road, you will cross over Interstate 94 then come to Priory Road, turn right on Priory Road and watch for the sign for the Priory on your right.

Methods:

Pace count is used in navigating, by knowing how much distance you cover with each stride you can estimate distance covered on the ground on a map. We  began by going outside and measuring out 100 meters using the True Pulse 360 B (figures 1,2), and then walking that distance repeatedly (figure 3). In doing so we were able to get an average pace count over that distance and estimate the distance we cover with each stride. My pace count was 69. With each two step pace I cover about 1.5 meters. Knowing this we can use the map to estimate distance to an object then use our pace to put that distance on the ground. We will use this in the navigation portion of the exercise next week.

Fig.1. One student walked out down the sidewalk while another
used her position to measure out 100 meters using the True Pulse.
   

Fig.2. Amy using the True Pulse to range the distance
of the student walking away on the sidewalk,  looking for
a distance of 100 meters.

Fig.3. Students walking 100 meters to get their pace count.

Construction of the map was done using Arcmap and Arccatalog. In Arccatalog I created a file geodatabase for navigation. Then I explored an assortment of data that was located on the university system in a geodatabase for the Priory. After looking at the data available I decided I wanted to keep the map fairly simple yet have usable information on it. I chose to use a color aerial image of the area of interest (AOI) which shows buildings and the overall lay of the land but also shows the varying vegetation types. I also chose to include a data set of 5 meter topographic lines. This data was obtained from the United States Geological Survey (USGS), as a 1/3 arc second digital elevation model (DEM).This is not a very precise data set, at 5 meters, but it gives a general flow of the topography in the area. The combination of the topographic data and the areal imagery should be very effective for compass navigation.

In Arccatalog, using the data located within the Priory Geodatabase, I used the toolbox and the clip tool to clip the data sets being used and save them into my navigation geodatabase. To accomplish this I used a polygon feature class which covers an area just larger than the property at the Priory. After the data was clipped and saved into my geodatabase I also copied the polygon feature class used to clip the data and another containing the actual property.

In Arcmap I set the work space projection to UTM Zone 15N, then had to use the project tool to project the polygons layers into UTM Zone 15N, and used the project raster tool to project the aerial image also. I layered the map with the aerial image on the bottom then the topographic lines over that. I included the search area, layered over the others, as a guide to limit our coverage during our navigation. Both the search area and the topographic layers were given bright colors to stand out against the background of the map. To aid in the navigation process I added a grid over all other areas. The grid is also set to UTM Zone 15N. The grid was added by going to the properties of the data frame then selecting grids. Select add new grid and finish the process. After the grid was been added I went back to the grid properties and adjusted the format to show lines at 20 meter intervals, label the edges so they were all readable when the map was held upright, and adjust the labels to only show the labels we wanted, the others were reduced font and given a light color.

I finished by adding a scale, a simple legend containing the search area and topographic lines, and a compass arrow designating north. These were each given backgrounds so they were easily distinguishable from the rest of the map. I also added the data sources, map projection, the name of the map maker and the date the map was produced. This was also given a background to make them more visible to the reader. the final map will be used in the field navigation exercise next week (figure 4). 

Fig.4. This is the completed map for use in the field navigation exercise. The map includes a base of aerial imagery
of the Priory, 5 meter topographic delineations, and the search area surrounding the Priory. A UTM grid at 20 meters was layered over the map to assist with navigation. All data layers were projected in NAD 83 UTM Zone 15N. 

    

Discussion:

While analyzing the data in Arccatalog I observed the projections of the data. All data that I used was projected into the same coordinate system to minimize troubles with data matching between layers. The data that was not used included 2 meter topography. This data was stored as a DRG file and many encountered trouble with the projection of it in Arcmap. The data had to be brought into the data frame in a specific order because the data frame will take the projection of the first item brought in. I chose not to use this data because it made the map to busy. There were too many lines for such a small area however a different project may have warranted the use of such data. We also had some aerial images that had higher resolution than what I used; however these were grey scale images and didn't show the vegetation as well as the color image. The color image was taken either in the late fall or early spring meaning the environmental conditions of the vegetation were very similar to what they are now in early March allowing for groups of vegetation to be easily distinguishable. Had we been doing this later in the summer the gray scale images may have been better.      

Conclusion:

For this project I found it useful to think about what the conditions were at this time of the year and what we were trying to accomplish. Using this information I made what I believe to be the best choice in data selection giving us a clear map with usable data and not over filling it with data we would not use or that would be impractical.