UKC

Hello everybody!

I'm an app developer and a few times a year I also go climb mountains.
I noticed that most apps in the App Store that measure your height aren't accurate and really don't look good.
So, my question is if anyone would be interested in such an app and if so which features it should really include.
Feel free to drop all your thoughts below!
If their is enough interest I will make an accurate altimeter app, I already searched a bit on the internet and I'm convinced that making a really accurate altimeter app, that requires no internet, is possible.

Thanks in advance,
Matis

In reply to Matis:

Surely the problem is that GPS is not terribly accurate in measuring altitude.
Phones don't have a barometer so therefore can't function as altimeters except by GPS.

In reply to Matis:

Search harder ! Already been done, the iPhone 6 has a barometer.

In reply to Matis:

There are some available on Android/iPhones, but way much better ones on Android (seemed more like a software issue rather than anything to do with hardware).

What I would like from an app is to see grid reference, altitude AND the accuracy (both horizontal and vertical, if possible). Some apps are completely useless as they say that you are in XX015000 and they suddenly update to XX017000 or something. Same with altitude, it takes some time to get the accurate coordinates, but I want to see how accurate they are. Gridpoint GB (iPhone) deals with that quite well, but it does not show the altitude.

On the other hand, Alpine Quest equivalent on iPhone would be quite cool. I paid almost 10 pounds for Android version, but now I have iPhone and there's nothing like this (or I couldn't find any).

In reply to splat2million:

I actually already did this. I made an app with just GPS and made a special algorithm that does the accuracy X5 so with just GPS you could have about 24 m accuracy but with my system you have about 5 in normal cases, best case 1 m, this is very accurate and I can assure you that it is the most accurate app that uses GPS. I will also include barometer for iPHone 6 which will make it even more reliable.

I hope you like it and I will notice you when it's online.

Matis

In reply to Matis:

Today, the app finaly went online. Be sure to watch it on the following link
https://appsto.re/be/clDg7.i
I hope you like it. The app is already really accurate and in further upgrades I promise I will make it even more accurate.
It costs 0.99c because I worked on it a while and really believe this Altimeter is better than others. I also need to charge this 0.99c because I'm only 15 years old and need to pay 90€ a year to be allowed to make apps on the App Store. I hope you can support me

In reply to Matis:


How have you multiplied the accuracy by 5? I'm willing to believe that you might know more about this stuff than me, I believe that the GPS systems have a built in error so you can't use them for strategic military purposes. I would imagine you would have some very powerful people after you if you have found a way round this issue!

In reply to ablackett:

Either the OP knows some deep, dark GPS knowledge that has evaded academia and the rest of society, or its a load of codswallop. As "I'm only 15 years old", I'm inlcined to think the latter. I don't want to seem like I'm picking on the OP who is clearly intelligent (I couldn't get an app to work) rather that his/her understanding of GPS and accuracy/precision is flawed.

GPS hasn't had built in error since 2000, when the error signal was switched off and GPS became mildly useful to the general public. Unsuprisingly, this is when SatNavs and handheld units entered the market. Improvement in hardware at the non-satellite end of the system means that precision can be as low as 3m in x and y for a device such as your phone with a dedicated GPS chip. For most of us, that's plenty. For lower precision (i.e. "less error", two units need to be used in tandem in correlation with a "known point".

I beleive the military now use a different system. In addition, Russian (GLONAS) and European (Galilaeo) systems are also being developed/launched as we speak.

In reply to ianstevens:




It might be possible to integrate the accelerometers, and combine that data with GPS locations into a probabilistic model (Kalman filter maybe) to eke out a bit more accuracy - but that would be rather difficult to do (it would easily be a university-level project). Secondly I vaguely recall hearing that mountains/valleys can produce echos that will result in much bigger accuracy problems - a quick look shows these to be called 'multipath effects'.

In reply to ianstevens:

cobblers, GLONASS has been on the go as long as GPS, and geodetic receivers have been using it that long.
as for accuracy x5 from autonomous GPS, even more cobblers.
multipath is a reflected signal, mountains arent likely to cause that, unless you're in a gorge.

In reply to ablackett:
Hello ablackett,
I will carefully explain what I mean with multiplying the accuracy with 5:
When I just used the altitude data in my app, the measurements where really inaccurate and jumping around it went from -33m to 20 m in a few seconde as in other apps. What I did is the following: In the app there is a method the get only the best measurements. This was already a huge improvement. This method only uses the best measurements with good GPS signal, it litterally filters the unpossible heights. Doing this made the app more realiable and accurate. This is something almost no other apps do. What I did next was making the height more steady. I took the average of the 10 best measurements in the past milliseconds and this really made it steady and always really close to the real altitude.
As I said multiplied by 5 I made an approximation. I used other apps to compare and believe me, most apps are really worthless. Looking at those apps my app was really much better. What I did wasn't making the signal more accurate, it was handling the data in a way that's efficient, reliable and no other app on the App Store does. If it came over as if I said that I made the original GPS signal better I am really sorry. However I didn't lie about saying that my app is more accurate than others. It really is. I compared the results of my app to places where the height is officially measured and of course it sometimes was 1,2, 3, sometimes even 5meters wrong but compared to other apps that were 50 m wrong this is really nothing.
Don't believe me? Buy my app. If it doesn't work as promised you can easily get your money back through Apple. I hope I convinced you a bit and if there's something else you need to know please let me know it.
Matis

In reply to Matis:

sounds fair enough. thanks.

In reply to Matis:

An altimeter app in Holland no one else find this amusing???

In reply to starbug:


Yes, the only country in Europe where you need to display negative values maybe?

In reply to Matis:

Worth a punt. The initial picture displayed fades to white with the elevation subsequently very hard to read? Elevation is 1m shy of my suunto reading so far.

In reply to Matis:

Eliminating outlier & low signal quality points and then averaging is a useful approach to take*. But you always need to remember that it is averaging, and therefore will have a delayed response to movement (The GNSS receiver in most consumer devices will have a position fix rate of 1 per second, so your filtering will be of the order of a number of seconds). That's fine for low dynamic motion (walking), not so fine for high dynamic activities. It's also worth being aware of the issue of reflections, as the GPS receiver really knows nothing about them, and SBAS (WAAS/EGNOS) cannot correct for them.

Glad to hear that you're not claiming the impossible. Congratulations on finding an opening in the app market, and for writing the app.

* e.g.
http://www.researchgate.net/profile/Jesse_Lewis2/publication/229452058_Effe...

In reply to PPP:
I have OS Locate on my Android which give 6 figure OS grid, ref altitude to 0.1 meter! and a compass and all accurate enough for my needs, tested in many places in the Peak cross referenced to 50k OSmaps. no interweb needed as works on GPS.

In reply to Bluebird:

Sorry for my late response, I had it too busy with school...
Today I sent an update for review and in about 6 days the update will be online if everything goes right.
This update solves the problem with the with background, makes the app available for iOS 7 and adds an Apple Watch version.
I will post again if it's online.

Matis

In reply to starbug:


Wouldn't it be cheaper to just write "5m" on your wrist with a marker pen?

what is "accurate"?
i'm using Xperia Z1 Compact and in "GPS Test" app alitimeter is accurate to about ~5 meters which is fair enough in mountains...