Author Topic: Track length calculation  (Read 2185 times)


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Track length calculation
« on: May 17, 2015, 03:09:04 AM »
Hi Scott,

I've been using TF-Pro with excellent success for years to lay out our races and calculate course lengths. Recently, my distances for 2 segments of a race were questioned. I suspect weirdness from the measurers, but thought I'd ask.

Specifically, we've got a "10K" course on the west edge of Brown County State Park in Nashville, IN. TF makes the course out to be 6.26mi; I had a report of 7.3mi from one person. The course is on-trail and off-trail with steep ascents and descents that include climbing over fallen trees and other stupid stuff, all natural obstacles, none of the "mud run" foolishness.

I was wondering if you'd have a look at the attached .gpx and give me an opinion about the accuracy of the length. It's a drawn course using TF, based on the accumulated .gpx files from years of wandering the woods there.




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Re: Track length calculation
« Reply #1 on: May 17, 2015, 08:02:14 AM »
Hi Ted,

Thanks for the post.  This is a good question.

If you have drawn this in based on multiple tracks in the area, I would tend to trust this track.  It looks pretty good to me... perhaps only very slightly short if I had to guess.

It would be interesting to compare tracklogs for people that are claiming 7+ miles.  I bet we would see a lot of error.  Running GPS units + tree cover = a fair bit of error.  And error tends to increase the distance, in most cases.

Hope that helps.

Scott Morris - founder and co-author of TopoFusion


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Re: Track length calculation
« Reply #2 on: July 22, 2015, 05:59:38 PM »
Other variables at play here;
1. model of GPS
2. can it be calibrated on-site, and if so, was that done
3. can the firmware be upgraded, and if so, what version (latest, 1-2 or more versions back, etc)
4. All using the same Coordinate Type and Datum settings, or not?