Re: 60cs tracback behaviour

From: Greg Brezinski (gregbr_at_shaw.ca)
Date: 08/09/04 

Date: Mon, 09 Aug 2004 07:38:34 GMT

the example i give is an example where there would be no restriction in
being able to walk along this path. i used a straight line in my example
because it is easiest to imagine - it is not where i would typically use a
tracback - only for sake of my example. yes a goto would work for this but
the straight-line example i gave is to more-simply illustrate how the unit
executes a tracback to a starting position when you activate it when you're
already on your return path to home.

why do i think it makes no sense? imagine i'm returning from my hike along
the same path as i went out. what if i broke my leg after walking east that
1/4 mile (please reread my example if this is unclear)? instead of the gps
immediately realizing i'm on the same track line as when i went out it will
insist on forcing me to crawl away from rescue (directing me 1/4 mile to the
west) and then have me turn around and recrawl the same path to the east,
finally arriving home after crawling the full mile. distance traveled -
1.25 miles...!

when i broke my leg i was only 3/4 mile from the starting point!

here's an simple diagram... imagine all these lines are on top of each
other and not offset as per the following: :)

<------------------------------------------------------START
my path out to the west from starting point

--------->(break leg - initiate TB)
i return eastward and activate trackback to "start" point expecting to
return 3/4 mile to the east.

<---------
instead unit tells me to return westward (3rd time over this segment) and
then...

------------------------------------------------------>START
turns me around (4th time over that track segment) and directs me back to
starting point.

I essentially will walk over the same piece of real estate 4 times. This is
not how this unit should be executing tracbacks... none of my other
garmin's do this... their tracback function is designed to eliminate areas
of the track that are redundant and bring you immediately back to the
starting point using the shortest possible path along the track line.

"Annapress" <annapress@aol.com.com> wrote in message
news:20040808130204.25491.00003114@mb-m29.aol.com...
> >here's an example - i walk for a mile in a straight line from east to
west.
> >i then decide to turn around and return to my starting point. after
walking
> >back to the east for let's say 1/4 mile i decide to activate "tracback"
and
> >specify my original start point (eastmost position) as my destination.
> >
> >what my 60 will do at this time is immediately point to the west and
insist
> >that i return that 1/4 mile to the west before correctly directing me
back
> >to the east and to my original start point. instead of having me walk
3/4
> >mile to the east i end up having to walk 1.25 miles first going west and
> >then back to the east.
> >
> (snip)
> >tell me i'm not the only one who thinks this kind of tracback behaviour
is
> >odd...
> >
> >please...
> >
> You're probably not the only one who thinks it's strange, but I would
suggest
> it is working correctly. When you activate track back, it should re-route
you
> through your entire journey. By definition, track-back should take you
back
> along the same route you followed between the time you started and the
time YOU
> ACTIVATED TRACKBACK. This is to take into account that this may be the
only
> way to get back (perhaps there's a mountain or lake in your direct path).
>
> Imagine this thought experiment. You start hiking northward from the
south
> side of a large lake walking around its west shore. When you get to the
north
> side of the lake, you turn east to go across its northern shoreline. The
lake
> shore isn't perfectly straight, it may curve southward for awhile before
> turning north again. You don't want trackback to try to direct you across
the
> lake just because you headed back south for awhile as you were walking.
>
> If you want to go in a direct path toward your starting point, use the
GOTO
> function, not trackback (but you have to remember to mark the starting
point as
> a waypoint for this to work).
>
> Steve

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