Priory Navigation with GPS

Introduction

This week we were once again at the Priory, this time with a GPS.  The goal for this activity was for each group to flag 5 trees at the priory, and to collect the geographic location of the points using GPS.  The objective for this activity was essentially design a new orienteering course that could be used in a future section of this class. 

Study Area

The Priory is located 3 miles due south of the UW Eau Claire campus on approximately 112 acres of land (largely woodlands).  More information on the Priory can be found in a previous blog post. 

Figure 1.  Map of priory location in relation to UW Eau Claire campus shown on left, map obtained from Priory Facebook page.  Aerial photo of Priory shown on right, image obtained from Google earth

 In order to make an orienteering course that went through as much of the Priory as possible, the different groups communicated with one another, and planned on different areas.  My group (group 5) decided to get our points in south eastern part of the priory.

Figure 2. Image of the priory, Group 5 area of interest outlined in red

 The majority of the area that we worked with was flat, but there was a small but steep trench that allowed us to make one of our flags more difficult to get to.  Most of the area we worked with had a variety of trees, except for the rows of jack pine which were less diverse.  There was also some construction debris in the area, and we found an abindance of broken tiles, and a broken washing machine.  Some parts were slightly thorny, but was relatively clear compared to the area that we were in the previous week. 

Methods

Before this lab started it was necessary to obtain a GPS unit, and have it ready for the activity.  I checked out a Trimble Juno GPS unit, and downloaded a topographic map of the Priory, as well as a geodatabase that could be used to collect feature points.  When working out how to accomplish this, it was useful to look back at the ArcPad data collection excersise.
We brought the Trimble GPS unit and a sharpie to the Priory, and there we recieved the rest of our supplies, a compass and pink flagging tape.  We realized that we had forgotten to bring a map, but fortunately we were able to borrow a map that had been produced by Emily Moothart. 

Figure 3.  Supplies used during the activity shown above

We began by plotting 5 points on our map in the area that our group had chosen.  We used that map to get close to the area, and than adjusted our points based on spots that we thought would be ideal.  When we found a tree that would work well we tied the flagging tape around it, and used the marker to write the group and point number on the tape.  We took a picture of each point that we flagged.  We made sure that the points we chose were a reasonable distance away from each other, and that you could not see any of the other points from one of the locations.  At each point, we plotted the geographic location in ArcPad using the Trimble GPS, and then took a picture of each of our points.

Figure 4. At point 1, after we have flagged the tree, collecting the geographic location with the Trimble GPS Unit.

Figure 5. At point 4, a broken washing machine can be seen a the bottom left of the image

Results

We collected 5 points that and labeled them 51-55.  We also took photographs of all of the points so that we know what they look like. 

Figure 5. Group 5 orienteering points shown with the imagery of the priory, labeled 51-55

Figure 6. Pictures taken from all of the Group five orienteering points, labeled 5-1 through 5-5

Figure 7. Group 5 Area of interest shown with its relative position in the priory as well as pictures of the orienteering points.

Discussion

The biggest concerns that I have with our results is that it is relatively difficult to determine how accurate we were.  The points that we plotted and mapped look like they are in the same locations that we were in the field, but with the resolution of the images that we have, it is difficult to say what level of accuracy we got to.  I think that it is reasonable to assume that we didn't make any extreme errors, and that the flagged trees are within feet of the plotted locations.

I had a lot of difficulty working the Trimble Juno GPS unit, and I wasn't able to get a base map to appear on the screen while I was using it, but fortunately the deploying of the geodatabase was successful and worked well.

We did not need to rely on navigation skills this week, because group member Joe Klees was very familiar with the area, as he was in a class with professor Garry Running who took soil samples in the general area that we were working in.  This combined with the fact that we drove and parked close to the location we were taking points further contributed to this exercise running very smoothly 

Conclusion

This lab was very useful to me, because forced me to recall previous activities in this class, and utilize the skills that I had learned in them.  Looking back at my past blog posts as well as the past assignments helped me remember the steps for properly setting up the Trimble Juno GPS.  This exercise also felt very practical, since we were actually helping set up an orienteering course for a future class.  Overall, it was a very fun and useful activity.