Quiz
• The purpose of this class is to develop your ability to do what three things?
Acquire field data
Process field data
Interpret field data
Navigation and Orienteering Purpose of Today’s Lab
• Learn how to: Read topographic maps Adjust your compass according to map declination Calibrate your ‘pace’ Navigate using a GPS and compass. Collect data with a GPS. Retrieve data from a GPS. Display GPS data in a GIS. USGS 7.5 Minute Quad
Map Reading Tips • Scale • Legend • Contour intervals • Magnetic deviation (true north differs from magnetic north • The top of the “V” that forms at the intersection of 2 streams point uphill; the bottom points downhill USGS 7.5 Minute Quad
• What does “7.5 Minutes” mean?
– Latitude & Longitude is measured in Degrees, Minutes, Seconds
– 1○ = 60' = 3600"
111○ 50’ 59” W
41○ 46’ 47” N Decimal Degrees Decimal Degrees USGS 7.5 Minute Quad • USGS Maps come in standardized sizes • What does “7.5 Minutes” mean? – 7.5’ latitude x 7.5’ longitude Why are USGS Quads so useful?
• Available for the entire USA, and many other places • Updated frequently • Consistent! 7.5 minute quads always have a scale of 1:24,000 – 1 inch on map = 24,000 inches (2000 ft) in real life – Useful for estimating distances
Using a compass: Azimuth (or Bearing) Using a compass: Declination Declination Determining your Declination
• Look on your map – Constantly Changing!
• NOAA Website: http://www.ngdc.noaa.gov/g eomag-web/#declination
• Declination for Logan is ~12° East
Adjusting Your Compass for Declination Navigating with Compass
• Example: Walk a bearing at 80○ Orienting a Map
• Positioning the map so that it matches what you see. • Requires a compass corrected for declination
(1) Turn the declination-corrected dial until “N” or “0” is at the index mark. (2) Place the compass with the index mark pointing toward top of map. (3) Turn the map & compass together until needle is boxed. Now North on the map and North on the landscape are the same!
A Brief Introduction to GPS
• Constellation of >30 satellites • Development started in 1973; system fully operational in 1995. • System funded by U.S. taxpayers ($750 million per year). • Operated by the U.S. Air Force • Accurate locations require direct line of sight between the satellite and GPS receiver • Vegetation can block signals
A Brief Introduction to GPS
• How does a mobile GPS unit work? • The mobile unit establishes a connection with at least 4 (of 32) satellites – Radio waves are transmitted + distances are calculated position on earth is determined
Interference may cause errors and diminish accuracy
How is distance to satellite calculated?
• Velocity * Travel time = Distance
• Velocity = speed of light
• Travel time = delay between when a signal is transmitted by a satellite and received by a receiver
GPS
• Coordinate System (or Position Format) is the method of reporting where you are on a surface. – Lat / Long – Degrees, minutes, seconds or Decimal degrees – UTM (UPS) – There are others…
Example: NAD83 UTM Zone 12N GPS: Datum • The earth is not a perfect sphere • The Map Datum is the method of how we approximate the shape of the earth – Best choice depends on where you are – There are many and we will be using NAD 83 – NAD stands for North American Datum
Image courtesy of ESRI GPS
• Projection: A way to place geographic locations from the globe on a flat map • Projections are chosen to minimize distortion • Our chosen projection: UTM – The units are in meters, which is handy for doing field work! Universal Transverse Mercator
• Your bearings will be in Northing (~latitude) and Easting (~longitude)
• You are moving along a grid, spaced out in meters.
• If you are moving straight East/West, your northing shouldn’t change, and vice-versa
– Useful for transects!
Using a GPS
• Allow a moment for your GPS to contact satellites It will need a clear view of the sky
• Confirm you are using the correct position format and datum.
These should be set to UTM UPS and NAD 83 for our purposes. The spheroid will adjust automatically.
Navigate to a waypoint • Where are you trying to go? • Hit FIND and enter coordinates. – You are the arrow – The pink line dictates the shortest path to your point – Many measurements are calculated using velocity…
In Summary… • Topo maps display lots of useful information – Declination, Elevation, Scale, Datum and Projection • Always check compass declination • Always check Datum and Coordinate System or Position Format on your GPS • NAD 83 UTM locations are represented in meters - In relation to the central meridian of your UTM Zone and the Equator
Today’s Lab:
1. Works in assigned groups
2. Submit individual assignment, Due next TH @ 0900
3. Submit on Canvas as a “Quiz”
4. Each group will check-out one GPS unit, 1 compass, and 1 measuring tape.
Today’s Lab: Four Parts
1. Using topo maps
2. Measuring your pace
3. Using GPS
4. Processing and visualizing GPS data Today’s Lab: Four Parts
1. Using topo maps
Classroom activity
1 map per group
Today’s Lab: Four Parts
2. Measuring your pace
1 pace = 1 stride = 2 steps
You must measure your pace before doing the GPS exercise
Today’s Lab: Four Parts
3. Using GPS Follow the directions in the tutorial Be sure to record your track AND a waypoint at each point you navigate to. Each waypoint must be renamed according to the Point Letter Designation = A, B, C, D, E, F Navigate to the points in the order you have been assigned (there are 9 unique orders)
Today’s Lab: Four Parts
4. Processing and visualizing GPS data
After you have navigated to all 6 points, return to the classroom and import your GPS waypoints and track to Google Earth on your laptop
Follow the tutorial instructions
Importing Data to Google Earth
• Tools -> GPS -> Import
• Help: https://support.google.com/earth/answer/1185357 ?hl=en&vid=1-635768231960376461-3103913036
• Capturing a track on an Android Phone or I-Phone https://play.google.com/store/apps/details?id=com .google.android.maps.mytracks