[pct-l] PCT Elevation gain/loss Stats

[Eric Lee]

Eric Martinot wrote:
>
But why the discrepancy from Jim (PITA)?   And what about the 600,000 ft
(110 miles) mentioned in other posts?
>

As other people have pointed out, measuring elevation change is prone to
large error for a variety of reasons.  The number you get is highly
dependent on the resolution at which you generate the data.  Elevation is
more sensitive to this problem than linear distance is, though it's true for
linear distance as well.

If you make the resolution on your elevation data too high you can actually
start to measure "noise" which would defeat the accuracy of the data.  What
happens when the surveyor takes off his pack (with the GPS attached) and
sets it on the ground?  Is that a 5-foot loss of elevation?  What about the
couple inches the GPS is moving up and down every time the surveyor takes a
step?  Is that reflected in the data?  Or if you somehow fix the GPS to the
surface of the trail, what about drain dips?  Do they contribute to
elevation gain and loss?  Small rocks?  Footprints?

Ultimately elevation profile data is fractal in nature - its length only
increases as you look closer and closer, and it does so practically forever.
You just have to decide how detailed is detailed enough and be content with
whatever answer you get at that scale.

Eric