Methode Gps De Polygonnage

GPS METHOD: “POLYGONNAGE” for agroforestry and other fields in the forest

GENERAL CONCEPTS: . The polygon that represents a field is considered a GROUP OF WAYPOINTS in the Garmin 12XL GPS which are “marked” in your unit. . A group of waypoints marked and saved becomes the POLYGON once they are saved in a series of points along the perimeter of a field.. Points are marked at important angle (azimuth) changes. . The series of waypoints that form the polygon are saved in a ROUTE that you create in the GPS unit.

PROCEDURE: 1. Stand at the first point , the takeoff point for the traverse around the field. 2. Create a new route for the polygon:  PAGE to the main menu screen, the list of action choices. ROUTE _ 1  Choose ROUTES ; push ENTER ZONE2POLY03_ _ _  At the top of the screen, select the number of the next empty NO WAYPNT DTK route, pushing up arrow ^ if needed. DS T  An empty route thus on the screen, push ENTER and go down 1 ______- with _ _ _ _._ until the next line. Here you can enter a comment to 2 ______- V _ _ _ describe the contents of the route you are creating around the _._ field (polygon traverse). 3 ______- _ _ _ Go through the blanks one by one to spell a description ; each _._ blank is filled in by using up and down arrow to pass through the 4 ______- alphabet and digits. As an example: Z O N E 2 P O L Y 0 3 indicates that the route regroups all the waypoints of the An empty route perimeter of the 3rd polygon in forest Zone 2. Push ENTER when the description is done, then QUIT the screen.  The route will remain empty until you add waypoints to it as described below. MARK POSITION WAYPNT 039  N 12O 41’ 15.8” W 011O 15’ 29.8” Add to route no. _ _

xxx AVG? SAVE? POLYGONNAGE OF AGROFORESTRY PARCELS AND FIELDS WITH GPS - PAGE 1 3. Mark the first point of the polygon and add it to the new route :  Push MARK and the coordinates of the point will be presented on the screen.  Before saving, there are 2 things to do : NAME, then ADD the point.  Select the Waypoint number by pushing ^ . Change the number, giving it a descriptive name such as « the first control point of the polygon » by spelling up to 6 letters and then pushing ENTER . For example, P 0 3 C 0 1 describes the first control point in the 3rd polygon (field). N.B. –The GPS Unit limits the name to 6 characters. Change the name of the waypoint Push ENTER to accept the new name.

POLYGONNAGE OF AGROFORESTRY PARCELS AND FIELDS WITH GPS - PAGE 2  Arrow down to “ADD TO ROUTE NUMBER __” . MARK POSITION  If it is not already on the screen, insert the number of the route WAYPNT P 0 3 C 0 1  you just created by pushing ENTER and using the arrows ^ N 12O 41’ 15.8” to get to the number from step 2. W 011O 15’ 29.8”  Push ENTER to accept the addition of this point to the designated Add to route route. no. _ 1  WRITE INTO YOUR NOTEBOOK THE NUMBER OF TEH ROUTE FOR THIS POLYGON/FIELD AND ANY USEFUL COMMENTARY, especially xxx the year in which the field was granted. AVG? SAVE? Add the waypoint to the new route

4. SAVE the first point of the new route: MARK POSITION  Move the selection down to the bottom of the screen to SAVE. WAYPNT P 0 3 C 0 1   Accept by pushing ENTER . N 12O 41’ 15.8” REMEMBER TO SAVE THE POINT!! W 011O 15’ 29.8” ADD TO ROUTE no. _ 1

REMEMBER TO SAVE THE WAYPOINT BY PUSHING THE BUTTON xxx ENTER AS “SAVE?” IS SELECTED AVG? SAVE?

5. The point MARKED and SAVED, walk on to the next angle change along the traverse and repeat step 3 « Mark and Add ». MARK POSITION WAYPNT For this second control point, spell a name that suits the logic of the first, such as P 0 3 C 0 2  N 12O 41’ 10.8” P 0 3 C 0 2 . W 011O 15’ 09.0” Add to route N.B. - As you travel to the next waypoint, ensure that the no. _ 1 GPS unit is still capturing satellite signals for accurate recording. xxx AVG? SAVE? 6. Continue along the rest of the perimeter to complete the polygon up to the last new waypoint. Name each waypoint in series. If you are careful, it will not be necessary to re-copy the coordinates of each waypoint as long as it is marked and saved by you.

POLYGONNAGE OF AGROFORESTRY PARCELS AND FIELDS WITH GPS - PAGE 3 7. Once you reach the last new waypoint, close the polygon as follows : ROUTE _ 1 ZONE2POLY03_ _ _  Go to the PAGE of routes and put in the number of the NO WAYPNT DTK DST traverse you are closing. 1 P03C01 - 125 0.3  Go to the next empty line of the route, and write (for the 2 P03C02 - second time) the first control point on the list. This example 206 0.4 illustrates that point 5 is empty; it is therefore the point 3 P03C03 - P03C01 that will be added to the list. Add the point by 299 0.4 4 P03C04 - pushing ENTER on the empty line, and spelling the point’s _ _ _ _ ._ name on it (the name of the point will be auto-completed 5 _ _ _ _ _ - with the help of the down arrow):

TOTAL DST 1.10 4 P03C04 - 310 0.9 COPY TO: _ _ DEL? INV? ACT? 5 P03C01 -

TOTAL DST 2.00 COPY TO: _ _ DEL? INV? ACT?

8. The GPS will automatically fill in the azimuth and distance (to the nearest 100 meters) between the last point and the first point. It will also calculate the total distance of the traverse.

9. Once closed, the polygon traverse of the field will not need editing, just transferring to the computer by the GPS software in « ROUTE » format. The only exception could be if the field changes shape over time.

10. OFFICE WORK: The “waypoints” that are grouped into a “route” form the polygon, one unique polygon per field. It is normal to add complementary data about the field on forms prepared in the office. The updating of these forms should be done at lest once a week. Complementary data include the following: s:  The year of field clearing or intended assignment.  Anything needed for project activities and monitoring, such as a list of all the trees to be cut within the field or landmarks in the vicinity.  A sketch of the polygon can also be made while waiting to download the data to produce a map. If that is attempted, the steps are described in the next pages.  IT IS NECESSARY TO REGULARLY EMPTY OUT THE CONTENTS OF THE GPS MEMORY, SINCE IT CAN HOLD ONLY 500 waypoints AND 20 ROUTES MAXIMUM; that is to say that the unit will be full after 500 points and you won’t be able to enter any more routes. Therefore a systematic program of fieldwork and downloading should be put in place with the mapping office.

POLYGONNAGE OF AGROFORESTRY PARCELS AND FIELDS WITH GPS - PAGE 4  The distances and azimuths from the POINTS ON THE TRAVERSE and “PERMANENT“ reference points such as bridges, buildings, or boulders can be recorded as described in the next paragraphs.

POLYGONNAGE OF AGROFORESTRY PARCELS AND FIELDS WITH GPS - PAGE 5 ESTABLISHMENT OF AZIMUTH AND DISTANCE BETWEEN REFERENCE OBJECTS AND POINTS ON THE TRAVERSE / PERIMETER OF THE FIELD

CONCEPTS: It is possible to continue working with your waypoints in the office. If the GPS unit sounds the alarm to re-initialize, push PAGE to receive the message and then select option number 3 with ENTER (« NO RE-INITIALISATION”). The “permanent” control points of the traverse are intersections with other roads, watercourses, or bridges that do not change geographic position. The coordinates of these points should be in the waypoint list of the forester’s GPS. The objective will be to determine the azimuths and distances between permanent points already known by the mapping person who manages the base map, and the point marking the start of the traverse (field boundary). From there, it will be possible to map the field in a geographically correct orientation.

PROCEDURE: 1. Push PAGE till you reach the main menu of commands ; choose DISTANCE AND SUN, ENTER . 2. The screen allows you to enter any two waypoints in the waypoint list of the unit. Spell the first one:

3. Go to the first empty space after “FROM” ^ and then DIST AND SUN push ENTER . FROM: ______Put in the name of the permanent point that is closest to the TO: ______first point of the polygon/traverse. The GPS will try to auto- complete each time it finds a point with the same letters you BRG DST enter. If several points have similar names, you should be sure ______you get the correct one. When the letter or name is right, _ . _ _ accept it with ENTER . If you need to type several letters, use right arrow to get to the next ones. DATE: 26 JUL 01 4. Repeat for the « TO » point, the first point of the polygon. SUNRISE DISTAND SUN 06:36:42 FROM: SUNSET PTGARG 19:17:50 TO: P03C01 N.B.: AT DESTINATION BRG = azimuth BRG DST 230o 0.45 km Screen with the azimuth and distance between 2 points in memory

5. The unit will automatically calculate the azimuth and distance between the two points. Note these numbers on the information sheet that accompanies the polygon/field archives.

POLYGONNAGE OF AGROFORESTRY PARCELS AND FIELDS WITH GPS - PAGE 6 6. It is best to calculate the azimuth and distance between two control points and the first point of the polygon/traverse, to triangulate the coordinates ; note both on the polygon/field information sheet. 7.If needed, the cartographer or forester can draw the exact location of individual fields on the base map of the forest, using a ruler, protractor, the GPS, and a paper covered in a half- centimeter grid.

POLYGONNAGE OF AGROFORESTRY PARCELS AND FIELDS WITH GPS - PAGE 7 SKETCHING THE FIELD PERIMETER: RELATIONSHIP BETWEEN GPS PAGES « DISTANCE AND SUN » AND « ROUTE __ »

CONCEPTS: To draw an outline of the field by hand on a quad paper, you need the azimuth and distance in meters between the points that were marked and saved within routes. The page “ ROUTE _ _” shows you the distances within 100 meters, which is not close enough for work at the scale needed to draw fields. The page “DISTANCEAND SUN” shows you the distance to the nearest 10 meters, which is more convenient.

PROCEDURE: ROUTE _ 1 1. From the main menu screen, choose ROUTES and plug in ZONE2POLY03_ _ _ the number of the polygon/traverse you want to sketch. NO WAYPNT DTK DST 1 P03C01 - 125 0.3 2 P03C02 - 206 0.4 2. In your notebook or on the information sheet for the 3 P03C03 - polygon, copy the azimuths between all the points of the 299 0.4 traverse, going down the whole list point by point as needed 4 P03C04 - 310 0.9 using down arrow V . 5 P03C01 -

TOTAL DST 2.00 It is not worth copying the distances yet, because they are too inexact. COPY TO: _ _ 3. QUIT the ROUTE page and go back to the main menu; DEL? INV? ACT? Select DIST AND SUN. DIST AND SUN 4. Now you can get the distances to the nearest 10 meters FROM: between each two points in the polygon. P03C01 TO: P03C02

5. The distances should be copied next to the appropriate BRG DST azimuths recorded in step 2. The screen DIST AND SUN can serve 125o 0.27 km as a verification by checking against the azimuths you copied in the ROUTE __ screen. 6. Draw the polygon on the quad paper. You can easily calculate the area of the field by counting the number of half-centimeter squares contained in the polygon. If each centimeter on the quad sheet is set to equal 100 meters, then the number of hectares is simply the number of squares divided by 4. ZONE 2 POLYGONE 3 26 ju 01 ZONE 2 POLYGONE 3

1 P03C01 -______125 0.27 1 cm = 100m km__ 2 P03C02 -______206 0.38 AREA 3 P03C03 -______299 40/4 = 10ha ha 0.36_____POLYGONNAGE OF AGROFORESTRY PARCELS AND FIELDS WITH GPS - PAGE 8 …..