For our next project we shall be navigating our way around a mini orienteering course close to campus without the use of modern day navigation technology like GPS devices. However, the weather here is Eau Claire is still bitterly cold (there was a wind chill of -3-F today), and there is still much snow on the ground, which would make the task quite challenging at the moment. So we are waiting until conditions improve slightly before carrying out our fieldwork. However, we can still learn about the skills we will need to use in the field in order to be able to find the markers in the field. We explored the more "old school" methods like pacing and compass work, and using the maps to relate yourself to the surrounding physical features what they were and how we could implement them.
We also had to create our own maps for use during our data point collection. This involved employing the computer skills in ArcMap, as well as being able to take in to consideration what elements to include in the map, and he appropriate projection to use for the data. Two maps needed to be produced for a Decimal Degree and Meters data set.
Methods
Pacing is the ability to work out your average number of steps over a certain difference in order to be able to remember this number and use it to calculate how far you have traveled in the field. By knowing the number of steps you usually take to cover a distance, by counting your steps whilst in the field, should be able to work our form the total amount of steps at x steps every x distance, how much ground you have covered.
As a class we went outside to work out our own pace count, so that we could use it in the future. We used the handheld laser distance measures like in the last project to measure out 100m. Then we each walked that 100 meters twice and took the average of how many steps we took each time. MY average was 66 steps, which is around about what most people got, as it's usually between 64 and 68. Except of course if you were particularly tall or particularly short, which would vary dramatically.
The class was then given a quick crash course in compass skills. How to read the values from them and what the different arrows mean were explained. Figure 1 below shows the different elements of a standard compass.
Figure 1: A standard field compass and it's elements ( © paddlinglight.com)
In order to gather where Magnettic North is we turn the compass dial (or bevel) so that the N (North) is in line with the direction of travel arrow. We then standing still move our bodies around until the red arrow is sitting on top of the red arrow drawn inside the compass housing. Calculating a map bearing involves placing the edge of the compass of following the direction of travel arrow point your compass on the map in the direction you are headed. Then adjust the housing until the orientating lines are in line with the latitude and longitude or coordinate systems on the map. The number that is now in line with the direction of travel was before, is the bearing. Bearings are technically given in 3 digit forms, which is fine if your bearing is e.g. 180 degrees, but if it is 20 for example, then we simply put a zero in front, so it becomes 020 degrees.
It is important to use all the information that a map is able to give you when navigating. people that are used to reading maps, especially topographic ones will almost be able to picture the landscape before you even see it. By looking at the contour lines (isobars of elevation) whose interval is usually marked on the map, the water features and having knowledge of how these and other parts of the landscape form can help you to predict what might be happening in the landscape. If pacing is not appropriate then the map scales can be used by utilising the string of your compass, or a nearby branch or something. If you measure a distance on the map, and then hold that up against the scale, you should be able to get the real life value. Sometimes, when a little lost it can help to take a look at significant features on a map and see if you can identify them in a landscape, and then find your place on the map from there.
In order to make our maps we set up a new geodatabase in ArcMap to save everything to the same place. It was important to ensure that the default geodatabase was set to our own, and that the works pace was pre-set to it also.Then the geodatabase that contained the different shape files, point line and polygon features had to be explored and experimented with in order to decide what would be appropriate for our maps. The sizes and colour schemes of different elements were altered to something that would be easily readable and visually pleasing.
A grid co-ordinate system needed to be added to the maps, as we would be plotting our data points later on out in the field. A different grid system was used for each map from the properties window of the layer, one mad use of meters and the other decimal degrees. This involved also having to select a co-ordinate system for each map. Co-ordinate systems are used to project the earth accurately, as the Earth's shape is actually a geoid and not a sphere as is commonly thought. So, a series of different methods of projecting the Earth on to a flat surface were created, each one however will distort the shape of the earth in some way in; direction, distance, shape, area etc. as it is not possible to deconstruct a round shape on to a flat surface without some degree of distortion. Depending on the area and what you are looking at the system you use will change.
Then some of the essential elements of map design were added using the insert drop down menu. This included; a north arrow, a scale bar and data, projection and co-ordinate system labeling, data sources and our names. AS well as other elements we wanted to include. These were then exported as JPEG images,for use when we carry out our fieldwork. Figures 1 and 2 below show the finished products of the two different maps.
Figure 1: The final map for use in collection of field points using a projected coordinate system that had metres as the units.
Figure 2: The finished map containing a coordinate system that had decimal degrees as its units, for use in data point collection in fieldwork.
Discussion
Pacing is such a basic thing but can be very important and helpful when it is needed. However in areas like thick woodland where there is perhaps lots of vegetation, tree stumps and roots on the ground, you have to take in to consideration that your pace will be a bit slower, It is the same of areas of high relief and in icy or snowy conditions. Also, if this technique is being implemented over a long period of time, then it can be very easy to loose count. A method we were taught to overcome this was to take a twig and every time you reach done of your units of measurement, you would snap it off and put it away fir safe keeping then count all the pieces you have and times that by the distance represented by each.
When deciding upon which map elements to use I added all the different elements at first and decided what was unnecessary as it it did not hold a purpose in helping me in t he field, what image worked better than others in terms of clarity. Also, some elements were obscuring the view of those more important and so were not included.
It is also important not to just stick to a bearing and follow it dead on from the compass, check it against the map and look around often. As we were dealing with the state of Wisconsin and needed something from the UTM zone, I chose the NAD 1983 (2011) UTM Zone 15N, as the projected co-ordinate system, this is one of two UTM zones for Wisconsin, and this is on this covers the area we are studying. NAD 1983 was used for the other map so that the units would be in decimal degrees, and it is a widely excepted coordinate system for U.S. datum.
Conclusions
There are many more skills involved in reading an interpreting a map, than people might have at first thought, It is this bringing together a mix of skills and elements that will make for an effective team in finding points in orienteering. How to use the compass correctly, calculation pace rates, looking at the landscape and identifying on the map, can all help greatly. The projection you use and it's influence needs to be thought about when adding a grid to a map, so as to still remain effective, and not obscure the area too much, which would then make it more difficult to navigate.
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