Author Topic: Altitude vs Elevation  (Read 357 times)

Offline Gomario

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Altitude vs Elevation
« on: April 27, 2021, 19:00:07 »
Hello everyone. Did any of you notice that Locus Map (android app) confuses altitude with elevation? It displays the elevation data under the altitude name  ;D Not exactly professional but not a big issue either. Many people confuse the two terms to begin with...
A more relevant issue is the fact that Locus can not display the Altitude at all ! This is sad because many people like myself find Locus very useful, as a "all rounder" navigation tool (in the air and on the ground). And the program already has all the data it needs. To get the correct altitude it only needs to substract the actual gps map location altitude from the actual elevation.
 

Offline Menion

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Re: Altitude vs Elevation
« Reply #1 on: April 28, 2021, 20:28:25 »
Hello Gomario,
thanks for the feedback. Mistakes happen, so let's do something with it.

From what I understand, elevation is the distance between the ground/surface and reference plane (usually ellipsoid). Altitude is then the distance between the user position (above ground) and the reference plane. If this is correct, may you please point me to the place where it is incorrect in the app?

From your text, it looks like you use altitude as a distance between the user position (above ground) and the ground itself. It is usually called "height" isn't it?

Quick search and the second image I've found explain what I tried to describe above.

Top links
- Official help desk (ideas, questions, problems): help.locusmap.eu
- Advanced topics, public discussions, sharing of knowledges, beta versions: you're here!
- Beta versions download: link
 

Offline Gomario

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Re: Altitude vs Elevation
« Reply #2 on: April 29, 2021, 15:48:49 »
Thank you for replying.
I must add right at the start, after buying the Android application and testing it in my microlight, I was very impressed with the accuracy and usefulness thereof. More often then not it was just as good as my dedicated (and very expensive) Garmin system. Clearly, technology has improved a lot over the last 10 or so years.
Comming back to the topic: In aviation we do not talk about "Height". it is a very confusing term and it is best left out entirely. "Altitude" it is used instead. But Altitude on its own can be confusing too. Hence we refer to ASL (Altitude above Sea Level) or AGL (Altitude above Gound Level). When used on its own, most pilots will understand it as ASL but as I said, you better specify.
On the other hand Elevation is used when describing the vertical distance to some object on the ground (or to the ground itself, right under the plane)
Mind you, after playing a bit more with the program on my phone, I see that the names can be easily changed. So please ignore my previous post entirely. I am still learning this thing and now my display is correct.
Lastly I want to highlight how usefull this program is for a pilot. I know it is not meant for flying but if you have a cellphone with a build-in barometer and compass, this program is quite impressive! However, it needs a bit of refining. Probably the functions are already implemented but I don't know how to use them  :'( How can i display the Elevation (Height above ground)? And I would like to see the vertical speed in m/s or feet/min instead of Km/h. Other than that most things are already there (including the Heading and Course lines!!!) The program does make use of the Internal Barometer and Compass. And is surprisingly spot-on even without accounting for the southern hemisphere geodesic .
And lastly, is there a way to implement the LiveTrack24 API? (https://www.livetrack24.com/docs/api)
 
« Last Edit: April 29, 2021, 15:54:56 by Gomario »
 

Offline Menion

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Re: Altitude vs Elevation
« Reply #3 on: May 24, 2021, 14:21:20 »
Hello Gomario,
sorry for the late answer.

Height: it is a little risky variable. Without precise offline elevation data (precise terrain model) and the accurately measured altitude, the value won't be useful at all. I'm also a little worried about the possible risk that may cause if anybody will rely on it during paragliding etc. So please rather use well-tested Garmin devices for this. Thanks for understanding.

Speed in m/s should be set in app settings.

LiveTrack24: there is no push on our help desk (help.locusmap.eu) to implement this feature so it is more a task for some independent developer who wants to train its skills and do some small add-on for the Locus Map.
Top links
- Official help desk (ideas, questions, problems): help.locusmap.eu
- Advanced topics, public discussions, sharing of knowledges, beta versions: you're here!
- Beta versions download: link
 

Offline Gomario

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Re: Altitude vs Elevation
« Reply #4 on: June 05, 2021, 10:45:00 »
Well, the height over ground is already all there but not displayed properly. At the moment the ground height I read it from the cursor position and the ASL is already implemented. All what I have to do is substract the two measurements from each other. It works OK but would like the program to do the subtraction for me  ;D
 What would be much more useful is displaying the calculated wind speed and direction! Unlike many other Android Navigation programs, Locus does use the inbuild magnetic compass data!!! That is a huge advantage when it comes to calculating wind speed/direction. You already know the instant heading (magnetic compass). You also know the instant course (GPS) and you also know the instant ground speed (GPS). Windspeed and direction is merely a simple calculation. The displaying can be done on the top right hand side of the screen by a arrow and number in Kmh. The top left is already displaying the compass. It will work out perfectly.
As for the accuracy thereof: I myself was pleasantly surprised. I have tested the unit on more than a dozen occasions and every time impressed me!!! Yes, you must do the compass calibration 'moves' before TO but thereafter it works like magic. As I said before, technology has improved a lot over the last 10 or so years. It is only a matter of time until more and more people will figure that out and make use of it. Locus is a pretty complete, all around navigation program. Only needs a few touches here and there. And I can assure you, a paraglider pilot's life does not depend on instrumentation. Worst thing can happen is for the pilot to land on some unknown field. Mind you, that happens now and then regardless on navigation skills/instrumentation :) Not a train smash though.  Aviation on the other hand is an entirely different story but that is not your market to begin with.
Oh, and thank you for bothering to reply ...
« Last Edit: June 05, 2021, 10:57:14 by Gomario »