Incorrect calculation of uphill & downhill elevation

[Thiodwitnir]

Description

The calculated uphill and downhill elevation sum displayed in track and route details is incomplete/ missing or wrong for some tracks/ routes.

Steps to reproduce

Navigate from 47.55293N, 11.79729E to 47.54634N, 11.79290E (Guffert Nordwandsteig) with a fresh install using the pedestrian profile:

Alternatively create a straight line track with just the start and end points from above and calculate heights from terrain map (red line in picture above)

Other locations (but not all?!?) provided similar results in my testing - reversing the examples shows incorrect downhill/ elevation loss calculation.
Even recorded GPX tracks show incorrect elevation sums.

Actual result

The displayed uphill elevation gain is incorrect - the height difference of start and end point alone is more than the calculated elevation gain:

Using just the track with only start and end points, the calculated elevation gain is zero:

Expected result

The elevation gain/ loss should be the sum of all inclines/ declines - and at least as big as the pure height difference.

Your Environment (required)

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OsmAnd Version: OsmAnd~ 4.8.6
Android version: 15
Device model: Pixel 7a
Crash-Logs: -

[Thiodwitnir]

Maybe related (and maybe not): the calculated steepness of the route above is „undefined“ for large segments - despite the graphs showing correct inclines/ declines:

[yuriiurshuliak]

If you're creating a route with the "Plan a route" tool using the Straight line method and notice no elevation data on the graph, follow these steps:

• Tap "Get elevation data" and select "Use Terrain maps."
• After calculation, you'll get a complete Altitude/Slope graph of your route based on terrain data.

Keep in mind that height data is stored in roads, so when roads are present, elevation can be calculated.

For more details, check the documentation: https://osmand.net/docs/user/map/tracks/track-context-menu/#calculating-missing-elevation

Also, try using our nightly version to see how it works: https://osmand.net/docs/versions/nightly_versions#nightly-builds