How Does TopoFusion Compute Distance?

[Cilantro13]

Something tells me it doesn't. See the attached files. I accidentally stopped the timer on an identical ride I did with my buddy. When you compare the tracks, however, his track is 1/10 of a mile shorter than mine. The problem -- there is a straight line (think hypotenuse) drawn where my GPS timer was stopped. On his track, he has the two legs of the triangle, so in reality his course cannot be shorter, but should be longer.

So I am guessing that the distance data is somehow embedded in the GPS track data? If so, is there a way to make Topofusion recalculate the distance?

(Full disclosure -- I downloaded my buddy's track of Geoladders. Also, on that note I love how you guys implemented climbing analysis in Topofusion that let's one see how the elevation gain is calculated with various algorithms -- I keep telling people that Geoladders likes to underestimate the actual climbing one does.)

(Sorry guys - I cannot post the files -- they are too big)

[ScottMorris]

TF does indeed compute its own distances -- it does not rely on any number in the file or from a GPS.

In your example it is likely some other portion of your friend's track is longer than yours, able to compensate for your straight line and more.  In general 1/10 of a mile is well below the precision of a GPS track's ability to measure distance on a trail.  So I am not surprised.

I can look at the files if you want, but if you compare them up close you'll probably see that his track adds in some distance elsewhere, perhaps simply by recording more points (higher sampling rate?)

[Cilantro13]

Interesting. I had no idea there were so many variables in the computation of the distance of a track. Thanks for the response.