Teams,
Now that we learned about elevation, contours, topomaps, ridges, valleys, bearings and positioning let's apply this knowledge in the field through a real-world hill navigation exercise. If required first read through this tutorial on reading bearings on maps and use of different types of compasses.
Assignment 7
Type: field assignment
Date: Tue May 2nd
Deadline: Sun May 7th
Duration: one morning or evening
Submit one set of answers per team
All team members to participate & understand
Planning a trail
First step is to select a small set of hills near your neighborhood / city (do not choose any large mountain range yet)
Create a trail (min. 500m, max 3K) using Google Maps across this set of hills through either or both:- Use of pre-existing trails (refer satellite map)
- Using ridges and valleys (refer contours on terrain map)
Important: ensure to view your trail in both terrain view (to see that it's not too steep) and satellite view (to see that the vegetation is not too dense). The hill range nearby Chengalpattu used in previous modules is not suitable due to dense vegetation.
Create a few interesting waypoints: e.g. start/end point, peaks, saddles, existing trails, etc.
Note: you can reuse the trail you created in the previous assignment #6 if you find it suitable for hiking (steepness, vegetation density)
=> submit screenshot of your planned trail on topomap (Google Maps) - answer 1
Preparing for the field
Export the trail through KML or GPX and load in Oruxmaps (refer previous assignment)
Choose "Switch Map" in Oruxmaps and select "OpenStreetMap CycleMap" to load a contour map
Zoom into 300m scale and move around the entire trail to cache the map in your phone (available in field without mobile network connection)
Ensure your phone is fully charged, switch off data before you step into the field to maximize battery life for GPS/navigation/map viewing
=> submit screenshot of your phone showing planned trail on topomap (Oruxmaps) - answer 2
Navigating the hills
Travel to the the starting point of the loaded trail
Enable the build in GPS of your phone
In Oruxmaps, switch on "GPS tracking" to show the current position
Switch on "Track Logging" to start record your trail till you reach the end
Now - similar as the field test in the plains - use your phone to hike along your planned trail in the hills
Following a pre-existing trail or ridge or valley is mostly straightforward. Only once in a while verify that you are still on track by checking whether your current position is still on the trail
Any interesting point you come across along the trail you can create a Waypoint in Oruxmaps
Taking Bearings
Once you reach an elevated location (e.g. peak) with sufficient visibility around you
Create a waypoint W0 for your current (reference) location and make a note of the latitude and longitude
Look around and try to identify any landmark which stands out (recognizable both in field and on satellite map)
Use your magnetic or electronic compass ("GPS Status" app) to take a bearing B1 from your current location to the landmark.
Now look for another landmark in the field (preferably approx. 90 degrees apart from previous one) and take bearing B2
Read your current Altitude A1 from either Oruxmaps or GPS Status app. Make a note of B1, B2, A1
Proceed along the trail until you reach the end point
Switch off "Track Logging" in Oruxmap to stop recording
=> submit screenshot of your phone showing actual recorded trail on topomap (Oruxmaps) - answer 3
Post-field trail analysis
Once you reach back home download the GPS log (actual trail walked) from your phone to your laptop (refer previous assignment)
Load the trail in Google Earth and view your trail in 3D from different angles
Enable the elevation profile for your trail => submit screenshot of your actual trail in earth view with elevation profile (Google Earth) - answer 4
Similarly load your trail in Google Maps (Create a new map, Import Trail)
Switch the basemap to Terrain View to view your actual walked trail and waypoints on the contour map => submit screenshot of your actual trail in terrain view (Google Maps) - answer 5
Compare the trail on the topomap with the elevation profile and try to correlate both (ascents, descents, peaks, saddles)
Locate the waypoint you created for your field reference location
Verify the altitude A1 matches with contour lines near your waypoint
Switch the basemap to Sattelite View and locate the waypoint W0 you created at your field reference location
Identify the location of both landmarks on the satellite map and create a waypoint W1, W2 for each
Create a screenshot of the map and copy paste it into a drawing app on your laptop (e.g. Paintbrush)
Draw two bearing lines B1, B2 through your reference waypoint W0 (refer tutorial on drawing bearings on maps)
Verify that the bearing lines B1, B2 are going through the respective landmarks W1, W2
=> submit link to screenshot of satellite map, waypoints for reference point and landmarks, bearing lines (Drawing App) - answer 6
Submit your answers above for review in following form.
Positioning
Similarly the bearings and altitude taken at the reference point in the field can also be used to identify your location on the map (refer module 6):
method1: contour line A1 intersecting ridge on which you were standing
method2: W1, B1+180 intersecting ridge on which you were standing
method3: W1, B1+180 intersecting with contour line A1
method4: W1, B1+180 intersecting with W2, B2+180
Try the four methods above by yourself and verify that every time the intersection corresponds to the waypoint W0
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