Lab 7: Field Navigation Using a GPS Unit



Introduction:

In the previous field navigation exercise, a simple field map and compass was used to successfully find particular locations at the Priory in Eau Claire, WI. While effective in identifying the hidden points, there were some issues that made navigation somewhat difficult. Chief among them was the process of step counting, and maintaining a perfectly straight bearing. The terrain and weather conditions were the main reason for these problems. Our step count values were obtained by walking in a straight line, on concrete that was cleared of any obstructions, making the journey very easy. When actually conducting the field navigation exercise, our path was anything but clear. There was at least a foot of snow on the ground, making step counts extremely inaccurate. Additionally, maintaining a perfectly straight bearing was complicated by the abundance of trees and shrubbery that covered the wooded area surrounding the Priory. Technology has allowed for some of these inconveniences to be remedied, and a contributing factor to that is the advent of portable GPS units. For this field navigation exercise, instead of using a map and compass, a Garmin E-Trex, shown in Figure 1, was used to navigate from point to point.

Figure 1: A Garmin E-Trex, the GPS unit used in this exercise
http://www.newsroute.info/TechReviews/GarminEtrexLegend.html

Methodology

Once arriving at the Priory, each person was given an E-Trex and a set of UTM coordinates. The GPS unit had to be calibrated to read your position in UTM, and once this was done, navigation could occur. To do this, the UTM coordinates provided to all the groups on the chart needed to match the coordinates on the GPS unit itself. Northing and easting directions were given, and to get where you needed to. If the northing needed to be decreased from your current position to get to the navigation point, you would walk south. If it needed to be increased, you would walk north. The same goes for the easting position. If it needed to be decreased, you would walk west. If it needed to be increased, you would walk east. By using these values, the group was able to efficiently navigate from point to point successfully. As with the previous navigation exercise, each point had a tool that you could punch you card, recording your successful finding of that respective area.
After completing navigation, the tracklog of the E-Trex had to be downloaded onto a computer to then import the data into ArcMap for manipulation. A program called DNR GPS, a piece of open source GPS software, was used to transfer the data off of the unit and onto a computer, where it was later saved as a point shapefile. The shapefile was then imported into a geodatabase, where it could become a feature class, and was finally then able to be brought into ArcMap for manipulation. All of the tracklogs from the class were uploaded to a feature dataset, so that all of the data could be accessed by everybody in the class. Figure 2 shows a map of my tracklog, and its relation to the navigation points that we had to follow. The video below the map shows a time-lapse progression of the navigation from point to point. Be sure to watch the video in full-screen to accurately see everything that is represented on it. Our group had to follow the 1A-6A points, which are marked on the map and video, and illustrated in Figure 3.

Figure 2: Individual tracklog for my GPS unit.

Figure 3: Copy of table containing UTM values used to navigate to the points.

The next map that was produced was one of all of the members in my group and their routes, shown in Figure 4. While this may seem redundant, as all group members should have the same tracklog records, this is not the case. When trying to find the navigation point, often times we would split up and look in different directions if we thought we were close. This cannot be shown on individual maps, but the group map can demonstrate this.

Figure 4: Map of my group's tracklogs in relation to the navigation points we were following.

Finally, the last map created was a collection of all groups that participated in the exercise, and the routes that they took to get from point to point, illustrated in Figure 5. As you can see, the courses took groups across the entire wooded area surrounding the Priory. Additionally, the paths cross in certain places, adding one more challenge to navigation, as each group had to be absolutely certain of their position, or risk steering toward a navigation point that was not theirs to find.

Figure 5: Tracklog records for the entire class, relative to the navigation points they were trying to find

Discussion

Figure 6 : Snowfall map of the state of WI on March 11, 2013.
Retrived from NOAA

As convenient as using the GPS unit to navigate through the various courses at the Priory, the process was not without issue. The first was something that could not be controlled: the weather. On the date of the field exercise, March 11, 2013, the Eau Claire area was hit with a fairly substantial amount of snow. Figure 6 shows a precipitation map of the state of Wisconsin on that day, with Eau Claire County getting almost eight inches of snow.  This made getting to the Priory difficult if proper precautions and planning were not done. Unfortunately, the group that I received a ride to the location did not take this into account, with a vehicle of a classmate being unable to drive in the snow. Thinking quickly, we used my car to get a number of people to the site. Unfortunately, at this time, we were already late for the activity, and the groups had left without us. After being given our GPS units, those who had been late were instructed to find their groups. For me, this was easier said than done. I attempted to find my group, but with no luck. The GPS unit was unfamiliar to me, and while I had an idea how to use it, trying to find the point where my group left was personally difficult for me. At one point, I managed to find another group, and I joined up and completed the exercise with them. I realize that this was not following the directions, and am disappointed in my perceived confidence with the E-Trex, which led me to having to abandon my group and join another one, just to avoid getting lost in the woods trying to find the navigation points on my own, while trying to look for my group members.
Another issue that was encountered was the accuracy of the GPS unit. Because of the heavy tree cover, sometimes getting a reading was difficult, because the E-Trex would pause while looking for a strong enough signal to give accurate coordinates. This was not an issue with the field map and compass navigation exercise, as the only thing that would prohibit our understanding of the map was our eyes. If we produced an accurate map, and had plotted direction and bearing values accurately, proper navigation was almost guaranteed. By using GPS units to navigate, we were at the whim of technology. If the tree cover was too thick, the E-Trex would not have a signal, and would render navigation impossible. Also, the GPS unit relied on batteries, which die after extended use. If the GPS unit ran out of power, it became just a rectangle in your hand that you can do nothing with. These pros and cons of using both a map and compass, and a GPS unit, need to be balanced with each other, and, using this balance and understanding of the limitations of each method, an appropriate tool can be selected to tailor the kind of navigation that is required.

Conclusion:

This field navigation activity demonstrated the benefits and drawbacks of using GPS units in attempting to successfully navigate a terrain. The technology that the Garmin E-Trex can offer in assisting the user in locate their position and move them from place to place is a significant improvement in using a map and compass to do a similar task. However, as technology often fails, the GPS units are susceptible to mechanical issues, like any other piece of equipment. Batteries can die, rendering the GPS itself useless. Tree cover can block a signal, affecting the accuracy of the plotted position. And operator error in reading the coordinates and understanding the unit can also prevent successful navigation. But even after considering all of these possible avenues for error, the GPS units do make the job of tracking and orienting oneself much easier than using a map and compass. While maps and compasses do not run out of batteries, or have their signal blocked from high levels of tree cover, they cannot tell you how far off course you are, or orient you in the right direction if a wrong turn is taken. At the end of the day, each method has its own benefits and drawbacks, and it is up to the person conducting field research to choose the method that will be of most use to them, and the one that will give them the most accurate results. 



Lab 6: Navigation Using a Field Map

Introduction:

Preparation prior to data collection is a key component to conducting work in the field. It allows for one to get right to work upon arrival to the destination, and also allows for the solution of anticipated issues or problems in the field. One can plan for a long time, but there comes a time when all that work can be used to assist in actual activities. This lab was one of those times. The field navigation maps that were created in Lab 5 were put to the test at the Priory in Eau Claire, a piece of property acquired by UWEC that is being used as the daycare center that was formerly located in the old education building on campus. A tour of the location can be seen by viewing the video on the right. In addition to the physical building on site, which used to be a monastery, an extensive nature area exists, which served as the location to be test the accuracy of our maps.

Figure 1: Printed version of the map created in Lab 5



Methodology:

In order to successfully navigate the wilderness of the area surrounding the Priory, the information collected in Lab 5 was required. The map created was needed, seen in printed form in Figure 1, as well as the step count for 100 meters. This would be used to navigate from point to point. Each group was assigned six points, with a copy of our group's show in Figure 1. Using principally the UTM X and UTM Y numbers, we then were able to use the UTM grid on the field map to locate and plot the points.
Once the points were plotted, distance and bearing values were required in order to get from point to point. Distance was calculated by using a straight-edge and connecting the space between the points. Using the scale on the map, each line was assigned a number of the space from point to point. Bearing values were calculated by using a compass similar to the one in Figure 3. The direction of travel line in the middle of the compass was aligned with each of the lines used in the distance calculation, the orienting arrow was lined up with the magnetic arrow, and a direction was then observed, and recorded.

Figure 2: The coordinates of the six points to be found.

Figure 3: A compass that was similar to the one used to calculate bearing values

The values of both the distance and the bearing fields can be seen in the table in Figure 4. The distance values were used in conjunction with the step count to approximate just how many steps were required in order to get from point to point. For example, my step count was 62 for 100 meters. Therefore, it would take approximately 266 steps to get from Points 1 to 6. The bearing numbers would be used in combination with the compass to orient traveling in the proper direction.

Figure 4: Calculated values for bearing and distance

Now that the preparation was complete, it was now time to go out and see how effective our navigation skills were. To do this, three roles needed to be filled. One person would need to serve as a position marker, by standing in a specific direction at the specified bearing. Another person, the pacer, would need to move from where they were standing to the first person, making sure to walk in a straight line. And finally, the last person would need to guide the pacer, ensuring that they walked in the same direction as the required bearing. In Figure 5, an image of me pacing the distance to the orienting point, the large tree in front of me, can be seen. Picking an orientation point was absolutely essential, as it was impossible to see from the start to the end point, and if it was, the entire activity would be fruitless, as finding the point with the map would be far too simple if it was clearly visible from the starting position.

Figure 5: Keeping track of steps from start to orientation point

Once successful navigation of the distance from point to point was complete, a suspended orange flag would mark the position of a punch card, each group being required to punch all of the points in order to successfully complete the activity. Figure 6 shows the card being punched after our group had made it from the starting position to the first point.

Discussion: 

Figure 6: Punching the card confirming our finding the point

This activity was a useful and educational experience. Relying only on the map that we had created, and directions calculated ourselves was a very empowering experience. We alone held the key to our success or failure. By far, the most challenging part of the activity was keeping track of the steps. As the pacer, it was difficult remaining in a straight line the entire, especially while trying to traverse the terrain. Navigation of the landscape would have been challenging enough by itself, but when one needs to walk in a straight line and take even-stepped paces through the snow is no simple task. Additionally, some obstacles could not simply be walked over or through. Sometimes, to keep accurate count, walking around the object and subtracting the lateral steps was necessary, adding one more hassle to the job of a pacer. But despite these challenges, we were still able to accurately traverse the landscape and find the points that we needed to find, and not the ones that part of other groups' courses.

Conclusion:

Navigating the landscape surrounding the Priory proved to be a challenging assignment, but as a group, we were able to accomplish it. Each member played an absolutely critical role in successful navigation, and effective communication between the group was required in order to move in the correct direction. As mentioned before, the air of accountability present here was almost refreshing. It was up to us to design a map that could be used to successfully navigate the assigned course, and if our map was ineffective, it was ultimately our faults if we were not able to find the right point. It was also nice change of pace to be reduced to using a map and compass for navigation. In this age of technology, where our phones are able to take us from Point A to Point B, not relying on any fancy gadgets to move around is a lost art, one that is not given enough credit. Paper maps don't lose cell coverage, and compasses don't run out of power. This method of navigation is one of the most accurate, and having to learn and use it effectively was an incredibly worthwhile experience.

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.