AllTrails app vertical tracking

[JJProwe]

I have been a regular user of AllTrails for years, no issues with it. I also use Gaia regularly. I actually notice it is Gaia that consistently underreports the elevation gain that I calculate on a paper map or I see reported by others on web sites like this one. In some cases it's total cumulative elevation gain is less than the summit elevation - trail head elevation, which seems impossible to me. Maybe I have it in some mode I haven't figured out yet ? But I do see people trashing AllTrails alot on various internet & Facebook groups. I guess it is the fashionable thing to to do. My suspicion is people not knowing how to use it, hoping that these apps are substitutes for knowing how to read a map rather than supplements ? I am usually cross checking AllTrails vs. Gaia vs. paper map. I also have used a Garmin GPS, which also underreported elevation gain. Not by a lot, maybe a couple hundred feet on a 3000'+ climb (similar to gaia). The Garmin was also a very useful tool, I quit using it only because with the phone apps that is one less thing to carry and worry about leaving on the roof of my car at the end the day.

I've noticed the same issues when I track with GAIA. Ultimately, I create my map in GAIA but use my watch data and Strava to get a better idea of actual elevation gain. I find the Strava-adjusted data is pretty spot-on.

[wineguy]

I never knew AllTrails had a user base outside of khaki-clad boomers.

Do you want a photo of me in khakis? Definitely a boomer.

[jrbren_vt]

GPS features on iPhone appear to be battery hogs anyway, maybe one more reason to use other technologies.

its not as bad as you might expect. on airplane mode, my phone lasts for 8+ hrs recording tracks with CalTopo.

also, if you just want to record distance and elevation for fitness purposes, get a watch.

What iPhone version makes an enormous difference. A couple of years ago I had an older iphone whose battery life made it unusable as a gps device on the trail. 4-5 hours battery life and it was dead, even in airplane mode. I upgraded 2 summers ago to the latest iPhone at that time and now I have plenty of battery life for about any day hike I will do (> 12 hours). I do have aback up charger for over night or cold weather trips. If you are conspiracy theorist there are many rumors that apple inserts power burners with software upgrades on older models so you'll want to by the newest phones.

[madmattd]

If you are conspiracy theorist there are many rumors that apple inserts power burners with software upgrades on older models so you'll want to by the newest phones.

I don't want to dive into this too much, but the reality is likely a lot less sinister: each year phones have processors capable of more work with less power usage than the prior version. The new OS each year is tailored to that new processor, and there's inevitably more and more stuff running in the background (at least on iOS, I'd guess Android isn't that different). The older, less power-efficient phones are going to have to work harder to run all the stuff in new OS's - thus burning through battery faster. Plus, after a couple years your battery has probably run through its rated charge cycles, inflating the issue.

[curt86iroc]

GPS features on iPhone appear to be battery hogs anyway, maybe one more reason to use other technologies.

its not as bad as you might expect. on airplane mode, my phone lasts for 8+ hrs recording tracks with CalTopo.

also, if you just want to record distance and elevation for fitness purposes, get a watch.

What iPhone version makes an enormous difference. A couple of years ago I had an older iphone whose battery life made it unusable as a gps device on the trail. 4-5 hours battery life and it was dead, even in airplane mode. I upgraded 2 summers ago to the latest iPhone at that time and now I have plenty of battery life for about any day hike I will do (> 12 hours). I do have aback up charger for over night or cold weather trips. If you are conspiracy theorist there are many rumors that apple inserts power burners with software upgrades on older models so you'll want to by the newest phones.

instead of replacing your phone, try just replacing the battery. its not that hard, but if you dont want to do it yourself, there are many stores that will do it for you.

[justiner]

If you are conspiracy theorist there are many rumors that apple inserts power burners with software upgrades on older models so you'll want to by the newest phones.

I don't want to dive into this too much, but the reality is likely a lot less sinister: each year phones have processors capable of more work with less power usage than the prior version. The new OS each year is tailored to that new processor, and there's inevitably more and more stuff running in the background (at least on iOS, I'd guess Android isn't that different). The older, less power-efficient phones are going to have to work harder to run all the stuff in new OS's - thus burning through battery faster. Plus, after a couple years your battery has probably run through its rated charge cycles, inflating the issue.

There were a lot of rumors on what exactly was going on - Apple came clean,

https://www.npr.org/sections/thetwo-way ... ttery-life

Could this impact GPS tracking? Perhaps.

It also makes comparing phones and GPS tracking precision hard - you can't just go, "my iPhone sucked, but when I moved to a (newer) Android, it was better. That's not apples (no pun intended) to oranges.

My guess tho is that AllTrails tracker and Brand X may just be using different recording intervals - or at least different speeds at which it doesn't, to save on power consumption, track size, etc. So for example, no tracks are recorded, if you're going < 2 mph in All Trails (made up numbers, btw just to make an example) and Brand X uses < 1 mph. Brand X will have more tracks to extrapolate data (and perhaps more noise) and the elevation gain/loss will be slightly more. And who knows what the algorithm they're using is to clean up that data. The GPS Visualizer doc really illuminates the problem that's being solved. Doesn't help that the earth isn't spherical, either.

[seano]

I've been experimenting with the tracking feature of the AllTrails app on my iPhone. It seems to understate elevation gains, compared to both my Garmin Dakota and Suunto Core. Anyone else have similar experiences?

GPS features on iPhone appear to be battery hogs anyway, maybe one more reason to use other technologies.

Low power mode on the iPhone still records a good track, and really saves on battery.

[martinleroux]

Part of the problem - especially with paper maps (as we're seeing with Lidar), is: what is, "correct" to begin with?

Exactly! Elevation gain and distance travelled aren't well-defined concepts, at least not for trails with lots of little ups and downs and sideways zig-zags. The more precisely you try to measure gain or distance, the greater the result. Actually, under some circumstances, there's not even any limit; the answer tends to infinity as your measurement resolution get finer and finer. This is the "coastline paradox", because there's the same problem when you try to measure the length of a jagged coastline with lots of little coves, inlets and promontories. (For a mathematical discussion, see http://li.mit.edu/Stuff/CNSE/Paper/Mand ... cience.pdf).

In practice, all apps and devices on the market use some kind of smoothing algorithm to avoid absurd results. But there's no universal standard for this, and different choices of smoothing parameters can produce materially different measurements.

Of course, most people are unconcerned with such issues, and are happy to think of their device as accurate if it produces results that are similar to other devices that other people have proclaimed to be accurate.

[greenonion]

Part of the problem - especially with paper maps (as we're seeing with Lidar), is: what is, "correct" to begin with?

Exactly! Elevation gain and distance travelled aren't well-defined concepts, at least not for trails with lots of little ups and downs and sideways zig-zags. The more precisely you try to measure gain or distance, the greater the result. Actually, under some circumstances, there's not even any limit; the answer tends to infinity as your measurement resolution get finer and finer. This is the "coastline paradox", because there's the same problem when you try to measure the length of a jagged coastline with lots of little coves, inlets and promontories. (For a mathematical discussion, see http://li.mit.edu/Stuff/CNSE/Paper/Mand ... cience.pdf).

In practice, all apps and devices on the market use some kind of smoothing algorithm to avoid absurd results. But there's no universal standard for this, and different choices of smoothing parameters can produce materially different measurements.

Of course, most people are unconcerned with such issues, and are happy to think of their device as accurate if it produces results that are similar to other devices that other people have proclaimed to be accurate.

Yep, just ask the deep military sources on these details. Whole nother algorithm.

Good explanation of smoothing for mapping purposes. Scale and resolution being considered of course.

[cougar]

its not as bad as you might expect. on airplane mode, my phone lasts for 8+ hrs recording tracks with CalTopo.

also, if you just want to record distance and elevation for fitness purposes, get a watch.

What iPhone version makes an enormous difference. A couple of years ago I had an older iphone whose battery life made it unusable as a gps device on the trail. 4-5 hours battery life and it was dead, even in airplane mode. I upgraded 2 summers ago to the latest iPhone at that time and now I have plenty of battery life for about any day hike I will do (> 12 hours). I do have aback up charger for over night or cold weather trips. If you are conspiracy theorist there are many rumors that apple inserts power burners with software upgrades on older models so you'll want to by the newest phones.

instead of replacing your phone, try just replacing the battery. its not that hard, but if you dont want to do it yourself, there are many stores that will do it for you.

I had my phone battery replaced and it list charge as fast as the old one, if not worse. Phone makers want you to buy a new one every year or two max, so they code a power draining timer into the phone, even if you replaced battery.

GPS measurement of angles and distance on slopes is a challenge to record every foot of gain or loss. Especially in
caves or underwater. Most of the apps use maps to correlate altitude and give stats.

[cedica]

I had my phone battery replaced and it list charge as fast as the old one, if not worse. Phone makers want you to buy a new one every year or two max, so they code a power draining timer into the phone, even if you replaced battery.

Apple is not a company, it's a cult.

(Older Intel based MacBooks are decent Linux laptops though. Not sure yet about ARM based newer ones, but I'll find out.)

[ECF55]

I actually notice it is Gaia that consistently underreports the elevation gain that I calculate on a paper map or I see reported by others on web sites like this one. In some cases it's total cumulative elevation gain is less than the summit elevation - trail head elevation, which seems impossible to me. Maybe I have it in some mode I haven't figured out yet ?

Truth.

Based on my experience, Gaia appears to use an elevation averaging algorithm for its cumulative elevation calculations. The app really doesn't like when you hike to a point and then turn around. I have seen it "take away" 200ft of my estimated elevation gain on some of those hikes after a turn-around. CURSE YOU GAIA!!

We also did an experiment once on a stairs section of a hike. On one flight, we took a multi-minute break on the ridge turn-around point and then compared it to the immediate (no pause) turn-around calculations. The section with the pause retained more elevation.

Gaia struggles with elevation gain calculations, but the rest of the app is gorgeous and incredibly useful.