How does Gaia Compute total elevation gain for a hike ?
Hi-
I have always noticed that Gaia GPS short changes me when me come to cumulative elevation gain for a hike.
Take a recent I hike I did doing Grizzly, Cupid and Sniktau (Colorado, near Loveland Pass) as an example.
Using Gaia GPS’s own data, I can measure these minima and maxima on the elevation profile it gives me on the web site, then compute all the
maxima – minima to give what I think should be the measurement for the day’s total elevation gain :.
Minima Maxima Delta
11989 12901 912 (Loveland Pass to ridge line)
12731 13125 394 (to Cupid summit)
12746 12933 187
12770 13433 663 (to Grizzly summit)
12770 12927 157
12743 13112 369 (to Cupid summit again)
12717 13152 435
13026 13229 203 (to Sniktau summit)
13019 13149 130
Sum of Deltas = 3450
I also had my AllTrails App running, and it did compute 3400’ & change of vertical for the hike.
I didn’t take any of the shortcuts or bypass trails, I went over every bump.
But Gaia GPS “Ascent” field reads 2969’.
That is off by 481’.
Perhaps it doesn’t count climbs that are under a certain threshold to avoid noise interference ?
Interesting that if this threshold was 200’, then the 130’, 157’, and 187’ climb above would not count.
Those sum up to 474’, which is pretty close, especially since my calculations are not that accurate.
If true, how do I lower this threshold ? Seems 20-50’ would be more reasonable.
I should mention I also do (using Gaia) bike trails like the Santa Fe trail in COS where the total gain of the walk of bike ride is around 100-150’ vertical, which would blow my theory above.
It seems to do well for hikes that are straight up one peak and then back down. It seems to always short change for rolling hikes. Maybe I am in some mode I need to get out of ?
The AllTrails App seems to be able to handle it.
I am not able to attach the gpx file. LMK if there is a way to send that to you for reference.
Thanks,
John Brennan
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People don’t understand that Gaia is storing points along a route line, not as a continuous line thus when it calculates altitude change it sums the altitude changes between each point not the sum of a unbroken line. So the result can be different from what a barometric altimeter will get. It is fundamental to how digital map data is stored.
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I don't follow. The barometric altimeter is out of the picture. The above is data that the Gaia GPS took from my hike. I measured it off the Gaia website for my track after I got home and sync'd my phone up with my account.. If I simply hand calculate the cumulative gain based on Gaia GPS's data points, no altimeter or line involved, I get over 3400' of gain. Yet the "Ascent" filed in the same trip report reports ~480' less. I am wondering what that "Ascent" field really means. The data is there, what is Gaia algorithm doing with it ?
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Is there a way I can share my GPX file here ?
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I have the same experience with gaiagps running on an iphone. I usually hike with a group of 3 - 5 people and each person uses a different device or a different app for tracking. Typically there are two different Garmin smartwatches and one Alltrails app running on an iphone. At the end of the day we always compare numbers and in almost all cases the cumulative elevation gain according to gaiagps is 10-15% lower than the numbers from any of the other devices or apps. It's become a ongoing joke among the people that I hike with. Often times we will hike a documented route where the milage and cumulative elevation gain is known before the hike starts. Still, gaiagps comes up with an ASCENT number that is about 10-15% lower.
The only exceptions to this have been when the hike is a simple up-down route with no loss of elevation from trailhead to summit.
I believe that the app is actually recording correct (or nearly correct) data because you see it plain as day when you look at the Elevation Profile. I have also done manual calculations for many hikes based upon what the Elevation Profile shows. Guess what, the manual calculations always result in a much more reasonable number for cumulative elevation gain. You don't have to be an expert in GPS technology to be able to see this. Just look at the Elevation Profile and then look at the ASCENT number for track. The two don't compare (unless it is simple up and down hike).
I've read a lot of responses to this that describe how data is recorded point by point and it has to with averaging and blah blah blah. I could be wrong but I think these responses are not addressing the issue. I almost always see an accurate Elevation Profile (i.e. the data collected by the app is correct, or close enough) and an obviously incorrect ASCENT number (i.e. the data is not being handled properly).
In the end, it works on the other devices and platforms, why doesn't it work here.
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wirosam - that is exactly my experience I am trying to understand. The profile data that Gaia took looks correct (by correct I mean it agrees with other sources, paper maps, etc...). But the ascent looks looks wrong (not by a lot, but enough to be annoying). Today I did a hike where the Ascent filed decreased from my reading on the summit to back at the TH. If that field is supposed to be total accumulated elevation gain, as I always thought, that should never happen. I am using an IPhone. Thanks for the reply.
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This problem has been driving me crazy. It makes the elevation gain reading essentially meaningless. I usually add a couple hundred feet to what it says, but that's just a wild guess. And as someone else noted, if you're doing pretty much a straight-up ascent, the reading will be more accurate. Can't we get a fix for this? It's the only thing about Gaia I dislike.
'
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Has anyone figured this out yet?
I stopped using Gaia over this issue. I love everything else about the app, but it was so annoying having my elevation consistently undercounted. I far prefer the rest of Gaia’s tracking ability to Strava (which I am now using), but don’t want to come back until I can get this elevation issue sorted.
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I never saw a response that answered the question. Whenever I am hiking and care about the elevation gain (which almost always in the mountains), I run Alltrails app in parallel. I use Gaia for logging my mileage and Alltrails for the vertical gain. The two apps always agree for mileage within a very small tolerance. I like the logs that Gaia keeps for me, just that one field is wrong. When I cross check against other sources, Alltrails is almost always spot on for that field, Gaia does not agree with its own data. But as pointed out, Gaia as other features I really like so I keep using it.
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I went downhill skiing today at Marquette Mountain in the UP. The Gaia elevation profile shows 15 ascents and descent at about 400 vertical feet each, which should add up to about 6000 vertical feet. But Gaia shows 2866 ascent, which isn't even close. My Suunto altimeter watch showed close to 8000 vertical, although i started it sooner than Gaia. I concur with the frustrations/irritations discussed above.
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I too am frustrated by this issue. Like others, I find Gaia GPS the easiest to use compared to other apps, but this one issue is potentially a deal killer. It would seem to be so easy for the app to report total altitude gain.
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