[pct-l] PCT Atlas - Clarification Please

[Brian Lewis]

> My GPS log has the distance from the border to Scissors at 75.3 miles.
>
> My logs constantly show the trail distances 2 - 3% less than the
> databook for the 1,000 miles of trial that I have logged so far. 

I find that using a GPS with NG Topo software pretty consistently gives
distances about that amount less than what independent sources report it as.
If I'm guessing correctly at your meaning here, Lon, I think that you're
saying that you look at the GPS track built from waypoints and see what the
Topo software says the distance is --- is that right?

I suspect a couple of factors at work here (at least a couple).  One is
whether the Topo software factors in uphill/downhill distance, or is looking
at it "as a crow flies the plot".   Another is just that inevitably the
track-built-from-waypoints is going to be a series of straightline segments,
approximating but never fully conforming to all the twists and turns of the
trail.

Recalling calculus, I guess if the segments get short enough then your
approximation gets better and better ... <g>

Apologies in advance if you meant something different and I'm
misinterpreting.



	Brian Lewis