Different elevation gain betwen web planner and app after using "Update elevation"

you will get different results with every other tool. That is quite normal.
In the web planner you have fixed parameters and height data. In the app you can use your own altitude data, the best is the LIDAR from Sonny.
And you can use different parameters and filters for the calculation. That's why it's different between the web and Locus.
If you want the same in the app as in the web planner, then you have to use the same elevation models and the same parameters and filters.
Just try something.

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You are now wondering which are the right ones. You can find out for yourself. But you need help to do this.

Take a longer route that is always uphill, never flat or short downhill.

Then you need the exact altitude at the start and at the finish. A professional surveyor can determine this for you. Sometimes there are also such points. Then start there and you know exactly what you need to get.

You can also use a good barometer if the weather is stable. This should also provide good results.

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Thanks. Where can I find the 'different parameters and filters for the calculation' ? Note that I am talking about the planner, not GPS data recorded during hiking.

And in the app I have the (default) elevation data from Locus store, so I would have expected the same result as in the web planner...

The same is true when creating a simple route in the app between 2 points: the elevation gain is X, and becames Y after using 'Update elevation'. What exactly happens with 'Update elevation' ? Why is the elevation data not used in the same way when creating the route ?

@Gergy Verjux:

1. you cannot make any altitude data settings in the web planner.
In the app under Settings -> GPS & Sensors (General) -> Altitude manager. The filter option (Altitude threshold) must be activated soon in the Expert Settings (Tracks & Routes).

2. I can confirm that there are (small) differences in the total elevation gain (and loss) for a route after 'Update elevation', even if you use the same parameters and altitude data. I don't remember (anymore) why this is the case.

@Graf Geo

Thanks. 1. does not make much sense imo, because creating routes should not involve the GPS sensor. Anyway, 'Use altitude offset' is ON

2. in the attached example, the elevation gain changes from 592 to 1009m for a 20km 2-point route. Not a small difference.

This route by Gergy Verjux in France is really strange. I re-planned the route in exactly the same way, both in the web planner and in the app it comes to 906 metres. After the update it was 1320 metres. If I recalculate the route (with LoRouter), I get 906 metres again. All with the "normal" HGT altitude data (not Sonny's). A huge difference.

I planned two test routes with the route planner in the app for comparison. First in the Alps: 1920 m, after the update 1959 m. A relatively small difference. Then a 71 km tour in the Pyrenees, 3932 km. After the update 4097 m. Again, a relatively small difference. I initially had no altitude data for any of these routes (there was a question mark at the cursor.) However, the route planner still creates an altitude profile and calculates the altitude data. If you want to update the altitude, you first get a message that you have to download the HGT altitude data. Only then can you update the altitude for the track.

This means that different altitude data is used. Usually the differences are not that extreme, but they are for Gergy Verjux's route. Unfortunately, I don't know why. Every recalculation of the route in the route planner results in 906 m again, every update (updating the altitude data) results in 1320 m again ...

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Thanks for your tests, @Graf Geo. Hopefully someone @Locus will have a clue...

Hi Gergy,

sorry for the late response, we tested the system, the data etc. The problem is in the interpolation of the elevation gain based on the "old" 3'' HGT files Locus Map app downloads when "updating the elevation". Especially in cases like yours - a long track along a steep slope in a valley - the result is really bad.

Solution:

- download more accurate HGT files from Sonny's server.

- store them in Locus/data/srtm folder

- restart Locus Map

We'll provide the accurate data in the future but before we have to develop a sustainable system for their maintenance.