Making Field Maps and Marking Locations

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Making Field Maps and Marking Locations
How to use a GPS
Garmin etrex Vista
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Goals
Build a base map for reference
Locate places so they may be found again
Navigate with confidence to a known point
Add location references to an existing map
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Basic Equipment
Garmin GPS (plus batteries)
Computer with a serial port
Serial cable for the GPS
Mapping software (e.g., GARtrip)
Scanner (optional your own base maps)
GPS map (optional commercial maps)
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Key Terms
Waypoint
Single points that you choose
Route
Waypoints assembled into a set
Track
Set of points automatically generated by the GPS
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How GPS Works
Signal time to arrival using multiple satellites
4 satellites minimum
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GPS Coverage Limitations
Works worldwide, equally well everywhere
Signal is degraded by vegetation cover
Signal is blocked by buildings
Signal goes through a windshield or airplane
window, but not the roof of a car or sides of an
airplane
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GPS Accuracy
Selective Availability
40 m
Normal Accuracy
20 m
WAAS Correction
Base-Station Differential Correction
m to cm
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GPS Constellation
29 satellites in orbit (8/01)
Orbits are not synchronous
Garmin GPS listens to 12 max at a time
Quality of the constellation varies
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Controlling the GPS Functions
click stick
page
zoom out
zoom in
enter (choice selection)
power(hold in)
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Pages
page
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Setting Up the GPS
Main page
Main Menu System Units
Coordinate format hddd.dddddº
Datum WGS-84
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Initial GPS Acquisition
Satellite page
May take several minutes to get enough satellites
No signal detected
CheckingID
Signal strength of confirmed satellite
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Map Display
Map Page
Current location and the direction you are moving
Scale
0.2 mi
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GPS Map Databases
Map page
Garmin Default
US Cities (general) and Foreign (general)
Garmin Supplemental
US Cities
US Topography
Foreign (some detail)
Some foreign countries (mostly Europe)
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Navigation
Navigation page
Waypoint destination
Honolulu
34.1 mi
Straight-line Distance
01 hrs 34 min
W
N
Bearing Pointer (toward destination)
Compass (direction you are moving)
S
E
Elevation
Time of Day
1103 ft
0406 pm
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Trip Computer
Trip Computer Page
These fields can be replaced with many
alternative types of information
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Main Menu
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Logging a Track
Main page
Main Menu Tracks
on
off
Track Log
0
Saved Tracks
10 unused
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Helpful Hints
Use GARtrip to manage your data
Go to the field with the locations of key places
already in your GPS
Save sets of location data as separate files
Mark locations of places that are important and
carry the GPS so you can find them
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More Helpful Hints
Check the batteries before you start
Clear out old data (use GARtrip)
Enter key waypoints (e.g., airports, cities)
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Marking a Location (Waypoint)
Waypoint Collection
Press and hold the click stick in (3 sec)
Waypoint is stored with number for its name Link
this number to your field notes
Waypoint Processing
Download to GARtrip using the serial cable
Save these waypoints in a file on the PC
Edit the waypoints by adding descriptors
Draw a map with the waypoints
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GARtrip
www.gartrip.de
30 per license
Major Functions
Basemap calibration
2-way data transfer
Waypoint editing
Map drawing
Route assembly
Track drawing
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GARtrip Exchanging Data
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GARtrip Editing Waypoints
Make sure your waypoints are loaded.
Highlight a waypoint and click Edit.
Name 6 characters max (no spaces)
Description 16 characters max
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GARtrip Assembling a Route
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GARtrip Calibrating a Basemap
Scan (or digital photograph) an appropriate map
(max 150 DPI). North up.
Save the scan as a GIF file (or convert to this
format).
Inside GARtrip, open with Map/Calibrate
Note You need to know the GPS location of two
places on the basemap.
The basemap will be used as a background for your
data.
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Exercise Set-up
Scan or digitally photograph a campus map that
will be used as a background. Save this as a GIF
file on the PC.
Check the GPS with GARtrip to make sure that
there are no stored waypoints or tracks.
Check that the GPS has adequate batteries and the
setup is proper.
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Exercise Data Collection
Start the GPS and make sure that it is
functioning properly.
Walk the perimeter of the campus, marking the
corners on the GPS. You will need two of these
points to calibrate the map.
Go through the interior of the campus marking at
least a dozen significant points. Record the
importance of each point in your notes.
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Exercise Post-Processing
Download the waypoints and tracks into the PC
Edit the waypoints by adding short comments to
each one.
Group the campus boundary waypoints as one route
and the significant points as another route. Save
these as separate files.
Generate a map using your significant points.
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Exercise Post-Processing
Calibrate the map inside GARtrip using two of
your perimeter points.
Add your significant points to the basemap.