PRACTICAL GPS APPLICATIONS IN

FORESTRY & AGRICULTURE MIKE CLIFFORD

VIRGINIA COOPERATIVE EXTENSION

• Introductions; Workshop & Field Testing Objectives

•Basics of the Global Positioning System.

• Features and operations of GPS receivers – Garmin eTrex series & others.

• Digital topographic maps - MapTech Terrain Navigator & Garmin Mapsource.

• Transfer of waypoints, tracks (area perimeter), and routes (cruise lines & plots).

• Set up cruise lines on Terrain Navigator and GPS units. Test in the field.

• Use GPS to calculate area in the field and compare results to

1. Traditional methods

2. Terrain Navigator's area calculation figures

3. Post-collection DGPS figures.

• Discuss available sources and resources.

• Evaluation and follow-up.

PRACTICAL GPS APPLICATIONS IN FORESTRY & AGRICULTUREWorkshop & Field Tests

GPS is short for Global Positioning System which is "a network of satellites that continuously transmit coded information, which makes it possible to precisely identify locations on earth by measuring distance from the satellites". Of course, many users also refer to their hand-held GPS receivers as "my GPS" ... as in the statement "my GPS' batteries went dead and I got lost!"

GIS is short for Geographic Information System(s). "In the strictest sense, a GIS is a computer system capable of assembling, storing, manipulating, and displaying geographically referenced information , i.e. data identified according to their locations. Practitioners also regard the total GIS as including operating personnel and the data that go into the system" ( from: http://www.usgs.gov/research/gis/title.html ).

GPS and GIS DEFINITIONS

BASIC INFORMATION PROVIDED BY GPS RECEIVERS . . .

YOUR CURRENT POSITION•COORDINATES (LATITUDE & LONGITUDE, UTM, MGRS, ETC.)•ELEVATION (APPROXIMATE)

DIRECTION TO SPECIFIED WAYPOINTS (“MARKERS”) (0R BETWEEN WAYPOINTS)

DISTANCE TO SPECIFIED WAYPOINTS (0R BETWEEN WAYPOINTS)

YOUR SPEED OF TRAVEL

YOUR DIRECTION OF TRAVEL

. . . AND OFTEN MUCH MORE

MAPS

TIME OF DAY

CROSS TRACK ERROR

ESTIMATED TIME OF ARRIVAL

ESTIMATED TIME ENROUTE

COORDINATES OF CITIES & TOWNS

AREA MEASUREMENT

ETC.

SOME GPS APPLICATIONS

• MILITARY• MARITIME • AUTOMOTIVE• SURVEYING• AVIATION• AGRICULTURE• FORESTRY• ENVIRONMENTAL• PUBLIC SAFETY

• HIKING

• HUNTING

• NATURE STUDY

• FISHING

• BOATING

• BIKING

• SKIING

• SNOWMOBILING

• GEOCACHING

• GOLF !

COMMERCE & GOVERNMENT

RECREATIONAL

HOW CAN WE UTILIZE GPS IN 4-H PROGRAMMING?EDUCATIONAL & OPERATIONAL USES

HUNTER EDUCATION

WILDLIFE MAPPING

HIGH ADVENTURE

TRIP PLANNING & SAFETY

SEARCH & RESCUE

LEADER TRAINING

FISHING & CANOEINGENVIRONMENTAL EDUCATION

BIG TREE SEARCHSCIENCE & TECHNOLOGY

AND LOTS MORE !

from GPS Land Navigation by Michael Ferguson

The NAVSTAR System

24 Satellites 6 orbital plates 11,000 miles up 12 hour orbit

from GPS Land Navigation by Michael Ferguson

THE EARTH: Latitude & Longitude

from GPS Land Navigation by Michael Ferguson

LINE OF SIGHT

ERROR SOURCES Multipath interference Atmospheric/Ionospheric Geometric DOP Clock Ephemeris S.A. (now turned off)

and Human Error!

Plot of position accuracy using standard Lowrance GPS receiver (stationary). Note the differences in scale

5.5 hour period immediately prior to shutoff of selective availability

8 hour period immediately after shutoff of selective availability

MAP DATUMS

• WGS84 World Geodetic System 1984 Default datum on Garmin and most other GPS receivers. Most accurate datum, but not yet in wide use on maps.

• NAD27 (NAD27CONUS) North American 1927 Older datum used on most USGS topographic maps. (We will be using this datum for the workshop)

• NAD83 North American Datum 1983 Very similar to WGS84. Used on newer USGS maps.

– and hundreds of others!

COORDINATE SYSTEMS

• LATITUDE / LONGITUDE (ANGULAR) DEGREES - MINUTES - SECONDS

• UTM / UPS (RECTANGULAR, METRIC) UNIVERSAL TRANSVERSE MERCATOR (WE WILL BE USING UTM IN OUR FIELD EXERCISES) UNIVERSAL POLAR STEREOGRAPHIC

• MGRS (UTM USING ALPHANUMERIC I.D.) MILITARY GRID REFERENCE SYSTEM

OTHERS …

TOWNSHIP & RANGE, STATE PLANE COORDINATE, ETC.

ACCURACYSTANDARD CIVILIAN RECEIVERS

(Selective Availability OFF)

HORIZONTAL ACCURACY TO 15 METERS (49.2’) OR BETTER

VERTICAL ACCURACY (altitude) TO 100 METERS (328’)

DIFFERENTIAL GPS (DGPS)

•Coast Guard•Commercial Ground & Satellite Based Correction•Wide Area Augmentation System

(WAAS)

SYSTEMS TO IMPROVE POSITION ACCURACY

WIDE AREA AUGMENTATION SYSTEMFAA SPONSORED GEO-STATIONARY SATELLITES (# 35 for us) FREE ACCESS ACCURACY TO 3 METERS INSTALLED ON MOST NEW (2001+) GPS MODELS

NAVIGATION BASICS

1. KNOW YOUR POSITION

2. PLAN YOUR ROUTE

3. STAY ON YOUR ROUTE

4. RECOGNIZE YOUR DESTINATION

Garmin eTrex Models with Area Measurement Capability “eTrex+”

Venture

$149.00Legend $209.00

Vista $285.00

ENTERING COORDINATES TO CREATE A NEW WAYPOINT IN ETREX +

• ON MENU PAGE, SELECT MARK.

• NAME IT & SELECT SYMBOL (optional)• ENTER ELEVATION (optional)• ENTER COORDINATE DATA• SELECT “OK” AND YOU’RE DONE

PROJECTING COORDINATES TO CREATE A NEW WAYPOINT IN ETREX+

• ON MENU PAGE SELECT FIND.

• SELECT AN EXISTING WAYPOINT AND ENTER• FROM MENU OPTION, SELECT PROJECT.• NAME IT & SELECT SYMBOL (optional)• ENTER DISTANCE• ENTER BEARING• SELECT OK AND YOU’RE DONE

CREATE A NEW WAYPOINT BY ENTERING A BEARING AND DISTANCE FROM YOUR CURRENT POSITION OR ANY EXISTING WAYPOINT

All 3 models

All 3 modelsLegend & Vista only

ETREX+ AREA MEASUREMENT: Venture Legend Vista

AREA MEASUREMENT TECHNIQUES

Using Venture/Legend/Vista GPS Receiver alone: *Calculate from perimeter measurement.

*Accessories - “area calculation” function. *Route - “route area’ function (not Venture).

Using Terrain Navigator (TN) alone: *Distance Tools - trace & calculate.

*Track Tool - trace, finish, calculate.*Route Tool - trace, edit/loop, calculate.

Using combination of GPS and Terrain Navigator: *Transfer GPS track to TN for calculation. *Transfer GPS route to TN for calculation. *Transfer GPS corner waypoints to TN. *Transfer TN waypts, track, or route to GPS.

AREA MEASUREMENT USING “ACCESSORIES”

1. On Menu page, enter Accessories

2. Enter Area Calc. (area calculation triangle).

3. Highlight and press Start (stop will appear).

4. Travel perimeter of the tract, then press Stop.

5. Record and save (as a track) if desired.

6. Clear the track log.

Area and perimeter measurements can be displayed in in a variety of units.

AREA MEASUREMENT USING “ROUTE” (Legend & Vista only)

1. On Main Menu page, enter Route.

2. Enter New (unless using an existing route).

3. Enter a sequence of waypoints (first and last should be the same).

4. Name and save the route.

5. Highlight route and select Route Area on the options menu.

• Area measurement can be displayed in a variety of units.• Perimeter and leg distances can be viewed as selectable fields

SETTING UP GPS CRUISE LINES & PLOTS OR OTHER LINEAR SAMPLING

IN THE FIELD WITH GPS RECEIVER: 1. Mark starting waypoint 2. Project (enter bearing & distance) additional plot points.

3. Create route (cruise line & plots). (This is one of several possible methods)

USING TERRAIN NAVIGATOR: 1. Mark starting waypoint; determine bearing & distances.

2. Use Route tool to draw cruise lines and

plots. 3. Transfer to GPS receiver. (This also is one of several possible methods)

TOPOGRAPHIC MAPS

AERIAL PHOTO TOPOGRAPHIC MAP

TOPO MAP MARGIN INFO: BOTTOM CENTERTOPO MAP MARGIN INFO: BOTTOM CENTER

TOPO MAP MARGIN INFO: BOTTOM LEFTTOPO MAP MARGIN INFO: BOTTOM LEFT

TOPO MAP MARGIN INFO: BOTTOM RIGHTTOPO MAP MARGIN INFO: BOTTOM RIGHT

DEMONSTRATIONS:

MapTech

TERRAIN NAVIGATOR

and

Garmin

MAPSOURCE

THE END