Introduction: The use of a compass as a tool to navigate the globe has spanned centuries. Without a good compass and map, sailors wouldn’t have been able to navigate seas limiting the extent of trade and expansion. The ability to use these tools to navigate has become somewhat of a lost art so to speak with the invention of global position systems or GPS. A location can be digitally entered and saved into these systems and the device will navigate the user to those logged locations; however, without the use of a map too, the path a user would travel may not be the most direct or advantageous. GPS also requires a strong satellite signal to operate with relative accuracy which isn’t always possible in dense vegetation or terrain one might find themselves in. This is where the simple compass beats out the fancy bells and whistles of GPS. Using a map and the bearings or directions of travel from a compass, one can successfully navigate as well or even better than a GPS. This exercise will demonstrate the time-tested method of compass navigation.
Maps: A navigator is only as good as their map. If the map representation of the area one wishes to navigate is incorrect, there is little chance that even with GPS navigation would be successful. For this exercise, we created our own maps as tools for later navigation races. The area where our navigation course is set up is called The Priory and is owned by the University of Wisconsin – Eau Claire Foundation. The Priory is 112 acres and is the home of a former monastery. The University foundation purchased and leased the land and structures to the University of Wisconsin – Eau Claire to provide a location for the Children’s Nature Academy and use the housing as a new resident hall for students. The area is mostly forested with stark topography created by the prehistoric ridge. Since the location wanting to navigate is local, a large scale map is best requiring a coordinate system and projection that has a high level of accuracy for these scales. It is also important to identify what information is necessary and what is noise. A navigation map needs to have essentials such as topography to see if in any mountains will be crossed in a path from point to point and several landmarks that a navigator can use as a reference. If the map is too busy or noisy, navigation is more difficult since the map is hard to read. You want to be able to quickly understand and find relatively where you are situated rather than spend hours just trying to find where you started. Data including a 5-meter topography and navigation boundary were acquired from a prepared database by the instructor Joe Hupy. A topography of an area could be acquired by using a 15-minute topographic map that is produced by the United States Geological Survey (USGS). The background satellite image was added in ArcMap using ESRI basemap datasets.
Methods:
Map Creation in ESRI ArcMap: As mentioned above, coordinate system and projection are the most important aspect to consider when creating a map. The local, large scale needed for a navigation map of The Priory required the accuracy and usability of a specific projection. The geographic coordinate system for North America updated in 1983 provided the base for the necessary projection. Using the North American Datum 1983 (NAD 83) Wisconsin Transverse Mercator projected allowed for the local level accuracy required. The state system provides better real world accuracy than just leaving the projection at NAD 83 since more local survey points were logged and referenced.
The map units of meters also helps monitor traveling distance in the calculations later to come when planning a route. Now that the projection was chosen, the data were added. An ESRI aerial image base map was used as the background but was set to 70% transparency to keep the map readable but still be able to use the image as a reference. The navigation boundary, structure boundaries, and 5-meter topography provided from the prepared database were then added over the image. Like the aerial image, the structure boundary feature class was also displayed at a 50% transparency to reduce map noise. The topography class was also displayed with the elevation labels to keep slopes orientated in the field with those on the map (Figure 1). For plotting the destinations, a graticule and map grid were created to assist in the accuracy of the locations.
Like mapping on a graph, the grids are used as a reference to help locate the positions or coordinates for the destinations and used to help determine the distance to those destinations. A grid using the Universal Transverse Mercator (UTM) measurements was added to plot locations given in meters or other UTM measurements (Figure 1) and another grid or graticule was added to help plot points given in decimal degrees from the Geographic Coordinate System (GCS) (Figure 2). The UTM grid lines always run vertically on the map regardless of where true north lies. This doesn’t always provide accurate locations for point destinations but at this large scale, won’t impact results greatly. Unlike the UTM grid, the GCS grid lines follow true north so are not vertical but are skewed to reflect the declination for the Priory location. This can provide better point locations when using a compass but, again, at this large scale, the discrepancies between UTM and GCS are minimized. The scale and representative fraction for the map were assigned and added by ArcMap. These are crucial in navigation as described shortly.
The Compass: The compass is an incredibly simple yet powerful tool. Compass navigation or orienteering is simple with a little bit of practice and knowledge of the compass itself. The most obvious feature is the bezel. The bezel is the rotating dial that holds the marked degree hashes used to determine bearings or direction you wish to travel. In the middle of the bezel you will find the needle as well as several index lines that will be explained in the Navigation section. The top of the compass has an arrow pointing away from the bezel this is your direction of travel. To use a compass, it has to be held flat in one’s hand parallel to the ground to allow the needle to rotate freely, and it is important to remember to keep the compass away from metal objects such as zippers in a jacket or a ring on your hand. The metal can affect the bearing from the needle. The needle has a red point and white point. The red always points to North therefore the white always to the South. The adage “keep red in the shed” refers to keeping the red north point in the designated red “shed” marked on the bezel. This is important for keeping the correct bearing when traveling.
Navigation: First task to complete when navigating on foot is to determine a pace count. A pace is counted when a person is walking and the same foot is set on the ground, so for example 4 normal steps are actually 2 paces. For the later navigation, my pace count was 64 paces in 100 meters. Each person’s pace will be unique, so if you are going to count with a friend, don’t worry if you get different results. When pacing, it is important to try to take as normal sized steps as possible since this is how you will be walking on trails or through the woods. Depending on the terrain you wish to navigate, an addition of 20 or more paces may be necessary if steep slopes are going to be crossed. So after determining a pace count the next task is to plot your destination points on the maps. If the destination coordinates are known, a user can reference the grid or graticule that was added to the map to help accurately position the points on the map. If the coordinates are unknown but the destination is a landform, that’s okay too you can still use the compass to travel successfully. Not only do you have to know the destinations but also the starting location. This will be the first point where you will have to use a bearing and distance. Once all the points are plotted on the map, the compass can determine the bearings. To assign bearings, first draw a line connecting the starting point and the first destination point. Then place the compass side along the drawn line making sure the direction of travel arrow is indeed pointing toward the destination and turn the bezel to line the index lines inside up with the North and South grid lines on the map. The number or degree now lining up with the mark with the direction of travel arrow is the bearing to follow when traveling. When moving toward your destination you have to be careful to keep “red in the shed”. This is easier to accomplish if you choose objects or features that are in the line of travel and pace to them and check your bearing. By splitting the distance into chunks it helps to stay on line and not stray resulting in a different destination. BUT WAIT! Don’t head off into the woods yet, you need to know how far to walk! Measure the draw line between the starting and destination points, then using the map scale or representative fraction, figure how long the path is in real distance. Once you have the real world distance, convert that number into paces using your pace count. So if a map’s representative fraction is 1:100, 1 meter on the map would be 100 meters in the real world. This would mean a distance measured to be 250 meters would actually be 25,000 meters. Then using the pace count, 64 in 100 meters in my case, determine the real world pace count, 64*(25,000/100). So I would travel 16,000 paces if the topography was relatively flat. Remember if steep slopes are in the path of travel, additional paces should be added to compensate for the smaller step size. The generic equation for distance to pace is PACE*(REAL WORLD DISTANCE/ PACED DISTANCE). As explained earlier, not only is finding closer features that are on line better to follow a bearing but it also helps to break up the pace count since counting to 16,000 isn’t the easiest to remember when you’re wandering through the woods. When using features, just remember to log how many paces it was to that feature then subtract it from the initial pace count needed to reach your destination.
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| Figure 1: A navigation map including 5 meter topography and an aerial image background for the Priory was created using ESRI ArcMap. A measured grid displaying in UTM is overlaid to aid in locating destination points. |
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| Figure 2: This is the same navigation map created before only is displayed using a decimal degree grid overlay. The decimal degree reference lines will aid in plotting points reported in degrees, minute, seconds or just decimal degrees. |
The Compass: The compass is an incredibly simple yet powerful tool. Compass navigation or orienteering is simple with a little bit of practice and knowledge of the compass itself. The most obvious feature is the bezel. The bezel is the rotating dial that holds the marked degree hashes used to determine bearings or direction you wish to travel. In the middle of the bezel you will find the needle as well as several index lines that will be explained in the Navigation section. The top of the compass has an arrow pointing away from the bezel this is your direction of travel. To use a compass, it has to be held flat in one’s hand parallel to the ground to allow the needle to rotate freely, and it is important to remember to keep the compass away from metal objects such as zippers in a jacket or a ring on your hand. The metal can affect the bearing from the needle. The needle has a red point and white point. The red always points to North therefore the white always to the South. The adage “keep red in the shed” refers to keeping the red north point in the designated red “shed” marked on the bezel. This is important for keeping the correct bearing when traveling.
Navigation: First task to complete when navigating on foot is to determine a pace count. A pace is counted when a person is walking and the same foot is set on the ground, so for example 4 normal steps are actually 2 paces. For the later navigation, my pace count was 64 paces in 100 meters. Each person’s pace will be unique, so if you are going to count with a friend, don’t worry if you get different results. When pacing, it is important to try to take as normal sized steps as possible since this is how you will be walking on trails or through the woods. Depending on the terrain you wish to navigate, an addition of 20 or more paces may be necessary if steep slopes are going to be crossed. So after determining a pace count the next task is to plot your destination points on the maps. If the destination coordinates are known, a user can reference the grid or graticule that was added to the map to help accurately position the points on the map. If the coordinates are unknown but the destination is a landform, that’s okay too you can still use the compass to travel successfully. Not only do you have to know the destinations but also the starting location. This will be the first point where you will have to use a bearing and distance. Once all the points are plotted on the map, the compass can determine the bearings. To assign bearings, first draw a line connecting the starting point and the first destination point. Then place the compass side along the drawn line making sure the direction of travel arrow is indeed pointing toward the destination and turn the bezel to line the index lines inside up with the North and South grid lines on the map. The number or degree now lining up with the mark with the direction of travel arrow is the bearing to follow when traveling. When moving toward your destination you have to be careful to keep “red in the shed”. This is easier to accomplish if you choose objects or features that are in the line of travel and pace to them and check your bearing. By splitting the distance into chunks it helps to stay on line and not stray resulting in a different destination. BUT WAIT! Don’t head off into the woods yet, you need to know how far to walk! Measure the draw line between the starting and destination points, then using the map scale or representative fraction, figure how long the path is in real distance. Once you have the real world distance, convert that number into paces using your pace count. So if a map’s representative fraction is 1:100, 1 meter on the map would be 100 meters in the real world. This would mean a distance measured to be 250 meters would actually be 25,000 meters. Then using the pace count, 64 in 100 meters in my case, determine the real world pace count, 64*(25,000/100). So I would travel 16,000 paces if the topography was relatively flat. Remember if steep slopes are in the path of travel, additional paces should be added to compensate for the smaller step size. The generic equation for distance to pace is PACE*(REAL WORLD DISTANCE/ PACED DISTANCE). As explained earlier, not only is finding closer features that are on line better to follow a bearing but it also helps to break up the pace count since counting to 16,000 isn’t the easiest to remember when you’re wandering through the woods. When using features, just remember to log how many paces it was to that feature then subtract it from the initial pace count needed to reach your destination.
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