Field Activity #6: Navigation with Map and Compass

Introduction

This weeks lab is a continuation of Field Activity #5 where I created 2 different navigation maps.  Our group of 3 will be utilizing these maps to plot and navigate to 5 different point locations created by our professor at The UWEC Priory.  The 5 points were marked on trees using bright pink ribbon and labeled with the appropriate number.  Our tools for navigation are limited to the UTM map we created and a standard compass. (Fig. 3)  Each person in our group of 3 had a specific job during the navigation process. One person was the compass holder, and pace counter, another persons stayed back to assure the person stayed on the correct course, and the final person was the runner (going wherever they were needed.)  We were given a GPS unit for backup, as from year to year some of the ribbons on the trees seem to disappear.

Methods

To start the exercise our group was given a list of 5 locations with the corresponding UTM coordinates.  Our first step was to plot the points in the correct location on our map.  Each group member plotted their own points on their individual map.  We compared the point locations on each others maps to verify the correct locations.  The list was organized but there was excess information cluttering the page and I read the incorrect number for one of the locations and had to correct it.  We then decided on a starting location which was easily deciphered on our map and plotted it as a point on our map.   After plotting and numbering the points we drew connecting lines between all of the points.

(Fig. 1) Casey and Katie preparing their maps for the exercise.

(Fig. 2) My map with point locations and lines drawn. 

After preparing our map we were given instructions from Dr. Hupy on how to utilize our compass for navigation.  The first step was to take the compass and line the edge of the compass up with the line you wish to navigate.  While holding the compass on the line I adjusted the compass housing (bezel) so the north arrow and the orienting lines on the compass line up with north and the grid lines on the map.  This gave met the correct bearing direction angle to our first point.

The next step was to calculate the distance we needed to travel to reach the first point.  Using the centimeter ruler on the baseplate of my compass I measured the distance from our starting location to point 1.  I measured 8 cm which equals 280 meters in the real world.

With the bearing direction my group member Casey took the compass while standing at our starting point she held the back (opposite end from the direction of travel arrow) of her compass to her chest and rotated herself until the magnetic needle (red) was inline with the orienting arrow (shed) this also referred to as "red in the shed".  With "red in the shed" Casey was now facing in the direction of our first location. 

(Fig. 3) An example of a compass similar to the one we used in the exercise.

From our previous calculation we knew the first point was 280 meters away from our starting location.  Casey stated her pace count from the Field Activity #5 was 67 paces.  This meant she would have to step 187 steps to reach point 1 if the ground was perfectly level.  However, the ground was not level, and our direction took us into the forest.

I had stayed back where we started to make sure her direction stayed true.  This method was only effective until she hit the tree line and then she was gone.  I caught up with her at the tree line and continued to watch her bearing.  Casey walked her 187 steps and we did not see a marker anywhere.  I remained at the location where her 187th step was, while she continued on her bearing direction to see if she could locate the point.  Meanwhile our runner (Katie) was wandering out front of our location to see if she could spot the marker for the point.

(Fig. 4) Casey and Katie searching for the first point location.

It wasn't long before Katie located a marked tree we believed to be the point.  After further inspection of the marker it was not our point.  At this point we were not sure how far off we were, so we consulted the GPS to compare our location to where we should have been.  After checking the GPS we realized we still had not gone far enough in the bearing direction and were off to the east a slight bit.

(Fig. 5)  The first tree we located with a marker, though it wasn't the one we were looking for.

After a short distance we ran into another marker on a tree.  We believed this marker was the point we were in search of.  Assuming this was our first point we consulted the map and calculated the bearing and distance to the second point.    I took the job of pacing and holding the bearing with the compass.  We were at the edge of a very steep ravine so pacing was not going to equal accurate results.  Before I started walking I judged the distance and used my pacing count to estimate how many steps it would take me to walk the distance.  After reaching the opposite side of the ravine and checking my bearing direction I continued on my bearing and pace counting.  After a very short distance Katie (I believe) found a marker on a tree.  Now we were confused again.  We consulted the GPS and confirmed we were at the proper location finally for point 1.  After inspecting the map closer there were topology lines which should have given us an idea we were on the wrong side of the ravine when we thought we had found the point.  (More on this in the discussion)

(Fig. 6)  Casey (Left) and myself (Right) examining the map for navigation from point 1 to point 2. 

Resetting my count and bearing direction we headed for point 2 with our prior calculations. The terrain was difficult to keep a good pace count on and hold your direction.  There was a number of ravines I would have had to cross to keep my bearing true.  I employed the same method of estimating the distance across.  When we arrived at the point where I felt point 2 should have been located, it was not to be seen.  Having been down this road before we consulted the GPS to check and see which direction we were off.  This time we had traveled far enough but our bearing direction was off slightly which put us off to the west a little bit.  We were still at the top of the ravine so we knew we had descend for sure and guess we would have to go up the other side.  When we hit the bottom of the ravine we checked the GPS and it seemed if we had went to far to the east.  After some wondering, we located the tree marker laying in the bottom of the ravine.  Using the GPS we finally located the location of point 2 which was about half way down the ravine slope.

From point 2 we calculated the bearing direction and distance to get to point 3.  Katie took her turn at pacing and holding the bearing direction.  The bearing took us back up the slope of the ravine.  When we arrived where Katie said the location should have been we couldn't just see the location.  After about 30 seconds I located the tree with the marker for the location.  She was almost perfectly inline with the point as far as distance but her bearing was off very slightly.

We used the same procedures for point 4 & 5.  We used the GPS to find location #4 as the marker on the tree was not there.  As we navigated from point 4 to point 5 it was getting close to the end of class time and darkness.  Casey took another turn at pacing.  When we reached were the location should have been we didn't just see it.  For the last time we consulted the GPS and we were not that far off and after a real quick search we decided to head back to the parking lot where we started the activity.  We used our map to get a bearing direction to head in for our return trip.  We successfully navigated back to our origin.

Discussion

This activity was full of learning experiences.  I was familiar with pacing prior to this activity.  However, I had never preformed pacing in terrain which varied in elevation this much.  The majority of my experience was on mowed trails which were relatively flat.  The method which I employed for estimating distance work fairly well but I am sure there is a better method.

The map I created for this exercise left a fair bit to be desired.  Prior to heading out in the field I felt as though the imagery of the trees would be helpful in navigation.  The basemap imagery did not help us locate ourselves on the map while in the forest.  The second issue I had with the map was the topology lines.  The spacing was probably adequate but the labels did not allow quick assessment of actually topology.  I believe using the DEM to create a better basemap and layout for topology would have greatly assisted us in our navigation. 

The 50m grid spacing for the grid lines made it tough to get an exact accurate location of the points.  Add the grid variability with the size of dot we made on the map with the marker and you already have a 10 meter approximation of location.  In the woods this approximation makes it difficult to locate places with foliage still on the trees.  Additionally, I made the grid color fairly transparent as to not hider visibility of the topology lines.  What I did not consider was we had to use these grid lines to set our bearing direction.  Doing it over again I would make them easier to see for a more accurate bearing.  Smaller grid spacing, larger scale, and alternate basemap would have greatly increased our accuracy for navigation.

Despite the issues we had with the first point, overall our navigation was fairly accurate.  I overlayed our track log from the GPS on the DEM and 1-5 point locations.  From this map you can see with the we were in the ballpark of all the point location.  You can see the issue we had locating the second point.  The 5th point which is the one we gave up on due to the darkness is depicted in the bottom of the ravine which we would have not have been able to see from the top.

(Fig. 7) DEM with track log from GPS, and point locations.

I don't feel the above DEM truly shows the elevation changes we encountered while trying to navigate.  I imported the DEM into ArcScene to create a 3D image of the landscape (Fig. 8)

(Fig. 8) 3 dimensional image of the terrain we navigated.

My fellow classmate Peter Sawall who helped me create the topology maps in Field Activity #5 showed me how to created an elevation profile using the DEM (Fig. 8).  You can see from the image the elevation change was significant especially for Eau Claire County Wisconsin.

(Fig. 9)  Topology profile created with ArcMap.

Conclusion

Overall this field activity was very educational in navigation trials and tribulations.  One of the biggest factors which would aid you in navigation is prior planning.  Learning and exploring your landscape prior to heading out into the field will greatly assist you in whatever your endeavors might be.  To be proficient at navigation in the woods, I would definitely need more practice and training.

Make sure to check out my group mates blog post.

Casey's Blog
Katie's Blog

Thanks again to Peter Sawall for assisiting me with advanced features in ArcMap.  Make sure to check out Peter's Blog.