Field Navigation Part Three

Use of handheld GPS units for field navigation.

Introduction:

Over the last two weeks our group, Andrew Peterson, Amy Bartel and I have completed two separate exercises associated with land navigation; those exercises included the use of available data and resources to create a navigation map, and using that map to do traditional land navigation using the map and a compass. The navigation exercise was done at the Priory and the immediate surrounding area. 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. For this week’s exercise we used modern technology (handheld GPS units) to navigate another portion of the area surrounding the Priory locating several points along the way.

Methods:

For this week we were not allowed to use a map to aid in our navigation. We were restricted to the use of handheld GPS units and given the coordinates of the points we were to locate (figure 1). The point locations were given in UTM NAD 83 coordinates. Our GPS units were also set at UTM. Again, there were three courses, each consisting of six points, to navigate and six teams navigating. One team on each course navigated the course forward (1,2,3) while the other team navigated the course in the reverse order (6,5,4).  Our group was to navigate the second course in the reverse order.

Fig.1. During this exercise we used a handheld GPS unit to
navigate to several points on one of three courses set up at
the  Priory, in Eau Claire, WI.

We began by starting a track log on the GPS to record our movements throughout the exercise. In order to locate a point we first checked the point coordinates of the point we wanted to navigate to, then we observed our coordinates on the GPS unit. Now the tricky part, we first had to get ourselves moving in the correct direction. In order to figure this out we had to ‘wander around’ a bit and figure out which way was which and get our bearings in relation to the point we wanted to navigate to. After we had a general idea of which direction we wanted to travel in we began to walk in that general direction, while walking we had to continue to watch our location on the GPS to be sure that we continued in the correct direction, adjusting our travel according to the easting and northing on the GPS (figure 2).  After we located a point we would repeat this process for each consecutive point until we finished the six point course. At the conclusion of the course we stopped the track log.

Fig.2. While navigating the course we had to
 maintain constant interaction with our GPS units in order to keep our bearings. 

After the exercise we downloaded our track logs using DNR Garmin software. We connected the units to a computer using the USB cable supplied then opened the Garmin program. We clicked on track and download. After the data were downloaded we went to file and save to our file as a shape file. Then in Arccatalog we import the shapefile to our geodatabase as a feature class and projected it in UTM, which we also saved into the Priory geodatabase for use by other students for their mapping. I added the locations of all of the points around the Priory to my existing map and then added my tracklog and created a map representing myself (figure 3). I then added the tracklogs of my teammates to the map and created a map of our combined efforts to locate our six points (figure 4). I gave each team member an individual color and shape to distinguish one from another.  Finally, I added all the available track logs from my classmates to the map in group layers. Each group was given a unique color and each member of the group was given one of three symbols, these same symbols were used for all groups. Then I finished with a map of the class’s efforts during this exercise.    

Fig.3. Map of the Priory with Stacy Camren's track log. There was a lot
of 'wandering' during this exercise. 

Fig.4. Map of the Priory with all of the track logs from the members
of my group. Note two track together and one separate from the
others, one member was late and had to navigate the course without
 the other two members.

Fig.5. Map of the Priory with all available track logs from the class.
There is at least one track (black) that does not seem to fit any of the
 courses, it was also not clearly identified in the geodatabase as to who's
track it was. 

Discussion:

There were several challenges this week; the first was getting our entire team together. One member of the team was late and we were forced to begin without them. Because of this we did not actually see the other member of our team until we were finished. The second challenge worth mentioning is both the new snow and the amount of snow present. The new snow was clinging to the trees very heavily and in some instances may have reduced the effectiveness of our GPS units by blocking or reducing satellite reception (figure 6). The amount of snow present made it incredibly difficult to walk in areas where there was a combination of a steep slope and snow cover that was more than knee deep (figure 7).

Fig.6. There was several inches of new snow , much of it
was still clinging to the tree branches and may have reduced
the accuracy of the GPS units.

Fig.7. Much of the area was covered with snow that was knee
deep and deeper making it very difficult to travel in.

The last of the large challenges was using the GPS to locate the UTM point coordinates. While navigating from point to point you naturally do not walk in a straight line. This can be cause by many things such as one leg being slightly longer or stronger than the other, or even the Coriolis Effect. But much of our deviation over these short distances was caused simply by obstructions such as trees, brush or in one instance a fence that had to be navigated around (figure 8). The difficulty was every time we made a directional change, either on purpose or not, we had to figure out what our bearing to our point should be again. This resulted in very inefficient direction of travel and a lot of misdirection; however, we did not have to be as precise when navigating around obstacles.

Fig.8. There were some areas that you are
forced to navigate around due to trees and
brush.

Overall we finished the course much faster than we did with traditional methods. Traditional methods used much more time to prepare and required more cooperation between individuals, however if done well traditional methods were much more direct.    

Conclusion:

It appears to me that each of these methods may have an appropriate use depending on time and manpower. Between these two I would choose to use traditional land navigation because of its simplicity and directness and the fact that I am comfortable with this method. If possible it would make sense to use both technologies simultaneously. It also would have made a difference to insert the navigation points as waypoints and navigate directly to them.

Field Navigation Part Two

Use of a compass and map for field navigation

Introduction:

Last week our group, Andrew Peterson, Amy Bartel and I, used available data and resources to create a navigation map. This map included the Priory and the immediate surrounding area. 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. Now that we have a usable map and we are at the location the map covers,; how do we use the map to navigate and what are we navigating to?

Methods:

After arriving at the Priory each group was given a list of coordinates (table 1) to points located in the area surrounding the Priory. At each of these points there was a numbered flag with a related paper punch denoting that flag and location. The flags were arranged to produce three individual navigation courses consisting of six locations each. As a class we had six groups of three people each. With only three courses, three of the groups would navigate the courses beginning to end while the other three groups would navigate the courses from the end to the beginning. Our group was assigned to the first course and would navigate it backwards.

Point #	Latitude	Longitude	UTM Y	UTM X	Altitude
1	44.76487	-91.51319	4957906	617662	313
2	44.76573	-91.51378	4958001	617614	301
3	44.76716	-91.5141	4958159	617585	255
4	44.76939	-91.51164	4958410	617775	260
5	44.76804	-91.51072	4958011	617970	278
6	44.76443	-91.51118	4957860	617822	297

  Table.1. Point number, coordinates and altitude for the six points 

  located on the first course. Two groups navigated this course, one 

  navigated the course in numerical order while the other navigated it 

  in reverse order.

The first step to navigating the course was to locate the points on the map. Our map had a UTM grid in place and we were provided with both Latitude and Longitude and UTM coordinates of the points (figure 1). To place the points we followed our grid with its labeled x-y coordinates and transferred the points from table 1 to the map (figure 2), our grid was set at 20 meter intervals so there was some interpolation to gain the most accurate position on the map. At each of the six points we marked the point with a permanent marker, this helped keep the marks visible during inclement weather, and labeled them.

Fig.1. This is the map we produced for use in this exercise.
The map contains and aerial image of the Priory, 5 meter
topographic lines, the search area we were constrained to
and a UTM grid overlay.

Fig.2. We are using the coordinates from table one to
plot our way-points  on our map of the Priory.

Now that we had our points plotted and we knew what direction we would be navigating in we could figure out our bearings from point to point and the distance between the points (table 2). To do this we used a map compass. The compass we used was my Brunton type 7. This compass allows you to utilize the grid on the map to set the compass to north after which you can simply read the azimuth bearing. OK  it is a bit more involved than that.

Points	Bearing	Distance (meters)
1 to 6	105	165
6 to 5	47	210
5 to 4	334	445
4 to 3	218	310
3 to 2	172	160
2 to 1	153	110

 Table.2. These are our point pairs and 

  their bearing and distance measures.

To gather the azimuth bearings from the map we begin by placing the long edge of the compass baseplate on the map using it to connect one navigation point to another one pair at a time, in our case we began by connecting point one with point six. We had to be sure the direction of travel arrow always pointed in the direction we wanted to move (figure 3), our point order was 1-6-5-4-3-2-1. Failure to do this could result in traveling the opposite direction we wanted. After lining up two of the points we turn our attention to the housing of the compass. The housing contains the actual needle and a series of parallel lines (orientating lines) in the bottom of the housing. In the North side of the compass housing there are also marks used to adjust for magnetic declination. In the Eau Claire area we have already determined the declination to be approximately 58 minutes west which is minimal enough that for the scale of this exercise we did not worry about it. We turned the housing until the orientating lines ran parallel to the north/south UTM lines on the map (figure 3). This was also critical; the orientation lines are bi-color black and red, red faces north and black faces south. The housing must have the red portion of the lines and the north arrow facing north on the map failure to do this could again lead to navigating in the wrong direction. After we lined up the edge of the compass between two points on the map and adjusted the housing to point north we were able to read our azimuth bearing. The numbers that run around the dial are azimuth. Located under the dial at the direction of travel arrow is an index mark, the number immediately over this mark is the azimuth for our direction of travel from point to point (figure 4). We repeated this process for each of the pairs of points on the map. Two of the sets of points were longer than the compass so we used straight edge from point to point and held the edge of the compass along it. To get the distances between each of the points we used the scale on the map and measured the distance from point to point.

Fig.3. This is a simulation of the UTM grid on our map. This was
done to clearly show how the orientation lines match the north/south
grid lines, the red portion of the lines and the north arrow are directed
north in concert with the map. Also note the orientation of the compass
in the direction of travel from point 1 to point 2. 

Fig.4. Here we can see the index mark beneath the dial of the
compass. The index mark is concurrent with the bearing arrow
on the base of the compass.  The sample bearing here is 148 degrees. 

For the field navigation we use the azimuth bearing we previously determined and the point to point distance. The three members of our group volunteered to each do a job navigating, the jobs were using the compass to determine our bearing (Stacy), pace the distance from point to point (Andrew)and to assist in determining the direction of travel (Amy). This worked well because we each had strong points. Andrew and Amy’s pace counts were very specific and did not very over several trials, and I had previous experience using a compass to navigate. To navigate from point to point we began using the compass to determine the direction of travel. I stood at point one and rotated the housing of the compass until our bearing for the pair of points was at the index mark on the compass housing. Then, holding the compass out in front of me with the direction of travel arrow pointed away from me, turned my body and the compass as one until the red portion of the arrow (north) was within the orienting arrow, also red, inside the housing. An easy way to remember this is “red Fred in the shed”. Once we achieved this we can look across the compass in our direction of travel. Just as when we were using the compass on the map we had to be sure the compass pointed in the direction of travel and that the red portion and north faced north or we would not be navigating in the correct direction. After we got our bearing Amy would walk out in that direction as far as she was able to while maintain a clear line of site with me (figure 5). When she got as far as she could go I would communicate with her verbally if she was close enough or using hand signals to get her as precisely in line as we were able. Then using the distance measured on the map and dividing it by 100 meters then multiplying it by Andrews pace count we could determine the approximate number of paces to the next point. Andrew would pace to Amy (figure 6) and we would repeat this process until we were at or in the vicinity of the point we were looking for. After reaching each of the points we would use the available punch to mark our card, evidence that we found the point (figure 7). Then we would continue on to the next point.

Fig.5. Amy is getting set on our bearing. At this particular spot
the large White Pine was directly in our path. In order to get
around it I had Amy go to the far side and hold her arms out so
I could estimate better where her body center was for our reset.
Andrew is aiding in communication. 

Fig.6. Andrew is pacing to Amy, the process of extending our
bearing and pacing our distance was performed until we reached
our next point.

Fig.7. Amy is using the punch at point two to mark our card.

Discussion:

We encountered several issues while plotting the points. The first was our grid, as instructed we used a universal transverse mercator (UTM) grid on the map. UTM will work with a global positioning system (GPS) system but not so well with a map and compass. Because we were using a compass and magnetic north we should have used a Geographic Coordinate System instead. However, this was not a large issue do the large scale of our map and the relatively short distances we were covering. The second issue was with our choice of marker used to mark the points on the map. We used a basic marker with a wide tip which does not allow for a very precise point, a Sharpie marker would work much better. When gathering the distance and azimuth data for the points we had to give it our best guess as to the actual point on the map. This may have influenced our readings slightly. We also had to account for the fact that when we tested for our pace count we were on flat level and clean ground, during the navigation exercise we were in knee deep snow traveling up and down steep hills. Much of the difference was accounted for by adding paces to the distance, not very precise though.

We were able to successfully navigate from point one to point six a distance of 165 meters. We were off by about 20 feet at point six. From point six to point five a distance of 210 meters, we were right on and had no issues. From point five to point four a distance of 445 meters we were not successful. This stretch contained areas with a very high density of brush and trees which in concert with the large hills caused us to make repeated calculations at short distances. Each time we had to reset we open the door for greater error in our navigation. This combined with the possible errors discussed earlier caused us to miss our target by about 35-40 meters. The time involved in the numerous resetting also limited us to only finding the three points. We were unable to finish the course as we were rapidly losing daylight.  

Conclusion:

This was a great exercise utilizing a very low tech tool, the compass, to do fairly accurate field navigation. Personally, I have used similar techniques to triangulate the position of radio collared animals. By using a radio antenna to get the direction of an animal from your position on a road and reversing the procedure described above  you transfer the bearings from your position to the animal onto a map. you would do this from at least three different points. Where the bearing lines cross each other is the approximate location of the animal. I enjoyed reinforcing those skills and techniques while getting to rummage around in the outdoors.

  

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.