Priory Navigation 2: Orienteering at the Priory

Introduction

As part of a comparative example of how technology does not have to be relied on for every task we set out to an orienteering course two miles south of the UW-Eau Claire campus. For those unfamiliar to the term, orienteering is a sport in which competitors use an accurate, detailed map and compass to find points in the landscape. A standard orienteering course consists of a start, a series of control sites that are marked by flags, and a finish. The location for this orienteering course was at the "Priory." A 112-acre parcel of land recently acquired by the University of Wisconsin - Eau Claire and now acts as the UWEC children's center and an individual room - dormitory.

The navigation course exclusively sticks to the surrounding areas. These areas have a host of forest cover, ranging from pine trees to a dense forest of deciduous trees and underbrush native to the area. For this exercise we were instructed to create two identical maps, with the exception of having one in UTM and another in decimal degrees. The maps were created prior to the exercise with the knowledge that we would be given the location of the flags once we reached the orienteering course. Upon arrival we were given the coordinates to flag locations and our respective courses.

Methods

This navigation exercise was completed using a map, compass, and pace count. More detail on the creation of the maps and how to find/follow a bearing can be found in a previous blog post. However the essential elements to the maps were decided based on simplicity and effectiveness. The trade off between detail and clutter was difficult to interpret. After careful consideration these elements were deemed "essential" to creating the most effective map:

• 2 & 5 meter contour intervals
• An aerial imagery basemap
• A grid overlay (added in layout view)

Using the map shown in figure 1 we were able to plot the points using the grid. For better understanding I have added a shapefile of the start/finish points as well as the flag locations. When we performed the exercise we were not given this shapefile. Instead we were given the table shown in figure 2 with the location and elevation of each point.

Figure 1 shows one of the maps used to navigate the priory course. Using the 15 points shown above, the course
was split up into three tracks. The track we navigated started at "2 Start" and included points 5-10. Originally the
groups were not given the point feature class indicating the exact locations of the points, instead we were given
a table with coordinates in UTM and lat. and long. which we were then supposed to plot on our maps using the grids
we created for each map. The map above was created using a UTM grid at 50 meter intervals.

Figure 2 shows the information describing the locations on
the orienteering course at the Priory. Either decimal degrees
or UTM coordinates could be used to plot the points. Another
useful feature was the elevation. The terrain at the Priory was
quite variable and often times knowing the elevation helped
guide your eyes while searching for the flags.

Figure 3 Shows a basic illustration of how
distance and azimuth can be used to find
a bearing and navigate a map. The image
also shows the starting point of our
navigation course. This view is from the
"runners" perspective looking back at
the person walking the pace count, and
the other in charge of finding the bearing.

Navigating the course worked most efficiently with one person in charge. The demand for one person to direct the others comes from the nature of the three tasks. One person must diligently monitor the group's bearing, another must keep track of the pace count, and another runs ahead to a land mark. The runner is more of a safety net. If the landmark (tree, rock, stop sign, corner of building, etc.; unique features) is in line with the bearing, then as long as the group reaches that location they won't be off course. Once at the land mark, the bearing is found, a landmark is picked out, and the runner goes to that new position. The next task is more a matter of consistency. As long as the pace counter keeps a consistent stride and walks a straight line, the distance to the orienteering flag should be accurate. We found once the runner reached the landmark, then the pace counter could start walking, and the compass holder could help make sure the pace counter was walking a straight line on the bearing. Figure 3 shows a quality example of the environment during the first section of the course, as well as a visual graphic of using distance and azimuth at a conceptual level.

Discussion

One of the difficulties came when the word "race" was introduced. Naturally everyone wants to win, so speed is a major factor. Unfortunately we learned speed was not the ONLY factor. With rushed careless work came results of the same quality.

One of the flags we struggled with was a product of hasty work. When plotting the points our analysis of where we thought the point was, told us to look on the East side of the hill. The flag was actually located on the base of the North facing slope. The green point labeled "8," in figure 4, shows where point 8 actually was, and the purple arrow in that same figure shows where we plotted the point. This error only was a difference of 30 meters or so, but this meant the flag around the side of the hill and out of sight. Looking at the contour lines of figure 4 can give you a better understanding of how the hill is shaped and the problem we encountered.

Figure 4 The yellow dashed lines show how the UTM grid can be used to successfully find point 8 (UTM_X: 617,928 and UTM_Y: 4,958,342....values taken from figure 2). One of the points was placed 30 meters farther south than the
actual flag location. This meant we took the path of the purple arrow, up over the hill and back down the other side.
In addition to the wrong location, we were also looking 10 meters higher than the actual flag location. It wasn't until we
looked at the coordinates again and found a more accurate location that we found the location 30 meters to the north west.

Figure 5 shows an example of how
vegetation can make following a bearing
difficult. Having to weave in between trees,
over fallen trees, through brambles, along
steep slopes, etc. All of these impact the
number of steps taken and create error
when trying to interpolate the correct
distance from the pace count.

Another problem we encountered was the systematic error that resulted from the changing environment. Areas that had dense foliage were difficult to traverse meanwhile keeping an accurate pace count and bearing. Figure 5 shows an example of one such difficult situation. In an ideal world a navigator could walk straight from point A to point B, without change in elevation or hazards. We were not in an ideal world, instead of walking the tangent we had to weave between trees, over fallen trees, struggle through brambles, and traverse steep slopes.

We found the longer the distance the greater the systematic error would be. The example of this was when traveling from point 8 to point 9 (figure 4, point 8 is centered in the northern portion of the map, and point 9 is on the eastern boundary line about half way up the map). Such a long distance increased the number of bearing readings we had to find and the chance of error from each new reading compounded to the point where we had to stop and think critically about the bearing we found and where we were on the map.

Figure 6 is an example of the pine trees found
on the eastern side of the map. Although the
area they covered was significant, the
orienteering course only included one point,
point 10, within the pine forest boundaries.
For the most part, the pine trees were devoid
of any underbrush.

Another aspect of the environment that influenced our orienteering was the thickness of the brush. Figure 5  shows and example of the thick underbrush that slowed us down and physically hurt to walk through because of the thorns. Then on the reverse side figure 6  shows the pine trees that were spaced out and in rows, devoid of underbrush. This area was the easiest to traverse, but also not a very large area nor a large component of the course. If you look back at figure 4 you can see the solid green semi-circle of green on the eastern portion of the map with only point 10 within it's boundaries.

Conclusion

After an immersive learning experience in the forest, we came out with a new understanding of orienteering. Our group actually finished tied for 2nd out of the 7 groups in this geospatial field methods class. We weren't without our delays and detours, but neither were the other groups. Our concluding thoughts of the lab were most exclusively focused on elements of the map that helped/hurt out navigation.

A general consensus by the group was that the base map was integral to successful navigation. Being able to look at your surroundings, analyzing tree lines, features in streams, gaps in the forest, etc. With just shape files and contour lines we wouldn't have been able to use many of the visual cues we ultimately relied on most to validate our progress between points.

Another aspect that would have been nice was more precise contour lines. The map I created wasn't used for the navigation, the maps we did use only had the 5 meter contour lines. Although these maps looked more aesthetically pleasing, we had a couple instances where reading the layout of the land was difficult, an example was at points 8 and 9 when the aerial image alone couldn't tell us exactly where we were on the map.

The grid was another topic of discussion. The initial plotting of the points exclusively used the grid; so, having a precise grid would have made plotting the point more accurate. Then on the flip side if you had a precise grid, say 20 meters, it would interfere with analysis during the majority of the exercise which was navigating from point to point. So the issues with the grid were how precise does a cartographer make it, and what color is best?

At the end of the day we were happy with our performance. I think, given the lack of everyone's orienteering experience, we performed admirably. The maps helped in unexpected ways when intuition was involved. And when the maps left us a little confused and wanting, we made do with creativity. In conclusion this was an effective exercise for group cohesion and on the fly critical thinking.