[at-l] Handbook/Companion/Data Book/Guide ??

[jbullar1 at twcny.rr.com (Jim Bullard)]

At 08:26 PM 1/7/2004 -0500, Alan Shorb wrote:
>One thing that hasn't been mentioned so far in this discussion is the
>profiles that come on the maps. They look like they would be very useful for
>planning a day's hike. But where I hear about them most are on
>trailjournals.com when someone complains about them having been misleading
>on a particular stretch of trail. My guess is that they are not made by
>someone who has hiked the trail, but are constructed in an almost
>mathematical manner just from tracing the intersections of the Trail with
>the contour lines on the map (As a mathematician, I am entitled to be
>denigrating of mathematical methods :-). So I'm not surprised that they are
>sometimes misleading, because they would tend to miss PUDs that are less
>than two contour lines in height.

The first problem with the profiles that appear on maps, or those produced 
by some computer map software, is that they exaggerate the height relative 
to the horizontal distance. The reason is simply that if they made them in 
true proportions (1:1 - Height:Distance) the profile would appear nearly 
flat. That would be really misleading. The exaggeration is intended to give 
you a more human scale sense of the incline but not everyone agrees on the 
degree of exaggeration that translates incline to them. The second problem, 
as you observe, is that something as small as a map can't show all the 
relatively tiny ups/downs that exist on the full sized terrain. Never mind 
the proverbial grain of salt, take profiles with a bag of salt. They will 
show which mountain is tallest and which valley is lowest. The rest is 
approximate.

Saunterer, the lover of maps