RE: [Philmont]: GPS

If you are marking waypoints yourself, and "stringing" them together, you
are basically cutting corners and will end up with a significantly lower
total distance that what was actually traveled.

I have an old Garmin 12XL which allows one to enter and link a sequence of
waypoints. It refers to this as a "route". The bread crumb trail,
developed from the unit automatically recording your position over time, is
referred to as a "track". Is the distance being questioned from a route
you've entered or a track the unit recorded?

On my unit, a route can contain a max of 20 waypoints, but a track probably
has several hundred points, so a track very accurately reflects where you
have hiked, and very accurately determines the distance (particularly over a
relatively short distance). A route, since it has a significantly smaller
number of points, "cuts corners" and doesn't accurately reflect your actual
path or distance traveled.

With regard to altitude, even on a steep trail I don't think the difference
in distance attributed to altitude is significant (a few percent),
particularly when compared to the variation between the path actually hiked
and the track the GPS is recording. This is especially true if the GPS is
tracking at an infrequent intervals and the trail is not straight. It can
have a huge difference in areas of switchbacks.

Are you looking at a "distance traveled" value reported by the GPS? It may
also be that you have areas where no tracking was done because of loss of
signal.

With my GPS I could download the track into a software application. The
track showed as a set of many straight line segments with gaps where the
signal was lost. Using the software I could reconnect segments or insert
new points and segments to assemble a sequence that more accurately
reflected where I had hiked. Of course, you don't really know exactly
where you hiked in the "loss of signal" areas, but if the areas are not long
you can refer to a map and get a good approximation. Anyway, after
"cleaning up" the track in this manner, the total distance will much more
accurately reflect the actual distance you traveled.

 -- Jeff

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Jeffrey W. Knoll
Venturing Crew 124
Phoenix, AZ
'02-627H
'04-610D

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Received on Wed Mar 12 16:54:46 2003