U S U / N A S A G E O S P A T I A L E X T E N S I O N P R O G R A M
O n T a r g e t 2 0 0 5
Application #4: Estimating Area Measurements
Estimating area in a field is a necessary task for many application areas of extension including agricul-
ture, business planning, and natural resource management. This GPS receiver has the capability to
estimate area measurements, even of curved and irregularly shaped areas. The following procedure
will not only generate area measurements, but will also provide perimeter measurements as well.
Estimating Area Measurement: The Track Log Method
As you travel the perimeter of an area, the GPSmap 60 records track points and uses the resulting
GPS track log to calculate the size of the enclosed tract. This method works well when you can rea-
sonably transport the receiver directly along the boundary of the tract. On small and irregularly shaped
tracts of land, you might want to increase the track log interval—the frequency at which tracks points
are recorded. Otherwise, you will lose accuracy when the receiver occasionally “cuts corners” as you
travel the boundary. Go to :
Main Menu > Tracks
> highlight and click
Setup menu
button. You have
choices here. The default setting is Record Method: Auto ( a combination of distance and time) and
Interval: Normal. If you choose to keep the Auto setting, you can set the Interval to More often or Most
often to increase the frequency of track points. Instead of Auto, you can choose to record by Distance
or Time, each with its own Interval settings.
Another attribute of the track log method is track-back of your route and a map. You can tell the GPS
to go back to any point in the tracks that you laid, and it will give you a map and a direction of how to
get there. However, that is more complicated than we are going to review in this pamphlet, so we’re
just focusing on the basics.
Follow these steps to estimate area measurements:
1. Generally you should clear the current active track log just before you begin laying tracks. Go
to:
Main Menu > Tracks > Clear
(If you wish to save the previous track, then save before
clearing the log).
2. Make sure that the GPS receiver is ready to navigate by going to the
Satellite Page
and
looking at the status window.
3. When you have confirmed that the GPS receiver is ready to be used, push the
Page
button
until you reach the area calculator page.
Note: The majority of your GPS units will not have the area calculator page accessible through
the page button, so to accomplish this, you will need to add the page to the page sequence. To
do this, access the
Main
menu, then select
Setup
, then select
Page sequence
. Then you
scroll down to get to
<Add Page>,
then just scroll down until you get to the
Area calculator
,
then
press
Enter
. Now your
Area calculator
is added to your
Page sequence.
