GPS distances

[TerryB]

From another thread:-

Distances between stays were measured using my HTC phone's Endomondo application and do not match perfectly those I found at Gronze.com site.

I am curious as to whether GPS distances take into account the vertical dimension? If I remember my geometry, the square on the hypotenuse equals the sum of the squares on the other two sides. As we walk the hypotenuse, not the base line and sometimes have a considerable height gain and loss, what difference is there in real (on the ground) distances?

blessings
Tio Tel

 

[nellpilgrim]

Hi,
Don't know about GPS calculations but good old 'Naismith's rule' serves pretty well so the standard version is:-
Allow 1 hour for every 3 miles (5 km) forward, plus 1 hour for every 2000 feet (600 metres) of ascent.
But I adjust it to 1 hour for every 4km plus 1 hour for every 500 metres of ascent.
And of course adjust to use the pace of the slowest walker (that would usually be me ) as your base line.
Nell

 

[Green Tortuga]

I am curious as to whether GPS distances take into account the vertical dimension?

In the grand scheme of things, the vertical dimension will wind up as mostly a rounding error. I'm not sure how much total elevation gain and loss the Camino can lay claim to, but I have heard that the Pacific Crest Trail has a total elevation gain and loss of about 300,000 feet from end to end. That's over a distance of about 2,650 miles. I've done both that trail and the Camino and let me tell you--the Camino is a heck of a lot flatter! So using that as a comparison.... with a 1,325-mile baseline (half the length of the PCT going up) and a 300,000-foot elevation climb (about 57 miles), the vertical dimension would extend the 1,325-mile distance to SQRT(1325^2 + 57^2) = 1326.2 miles. For a difference of 1.2 mile. Then another 1.2 miles to go back down the 300,000 feet on the downhill side of the trail.

So basically, over the entire length of the 2,650-mile trail, the vertical element would add (roughly speaking) about 2.4 miles to the length of the trail--not even 1/10th of 1%.

And the Camino has nowhere near the ups and downs found on the PCT, so the difference for the Camino would be even less than that.

The curvature of the earth probably has a bigger impact on the distance traveled than the elevation gain and loss!

-- Ryan