Elevation gain/loss on planer to high

Started by HarryH, July 30, 2023, 14:57:22

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HarryH

Hi,

the calculation of the elevation gain/loss is much to high.

See here https://link.locusmap.app/r/1w8ps3. It calculates 2145 HM!

The same route is stated here on Outdoor Active. There we have around 1600 HM

I hiked this route myself, so the value of Outdoor Active is the realistic one.

When I check the same route on LocusMap Classic and on LocusMap 4, both for Android, I got the same overestimated elevation. The same effect I see also for other routes.

This was not always so. It seems that some time ago there was an update on elevation calculation, which produce wrong and to high elevation gain/loss. E.g. if I just update the elevation data for old tracks on my phone, I got increases of hundreds of HM.

So, please correct this behavior!
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Tapio

#1
There's no 100% right or wrong but yes, drastic differences. You noticed the "Altitude threshold" slider in track options? That's the recent change in LM.

Let's just talk about that fixed track from OA. I have attached it.

And there is a bug. I have attached it slope colored (auto range) and the result ist mostly green.
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Menion

Hi guys,
- the difference is indeed big, but it is not a surprise as Tapio wrote.
- we plan to use a more precise elevation data soon, so results will be more precise mainly in highland areas
- the slope is mostly green because there is a segment with a huge slope value. So a limit to -50/50% is necessary.
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Tapio

#3
Quote from: Menion on July 30, 2023, 16:34:48the slope is mostly green because there is a segment with a huge slope value. So a limit to -50/50% is necessary.
Ah, yes. Those local extrema easily make auto slope color useless, maybe let algo look more broadly?
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Menion

Two weeks ago, the algorithm on the web planner was updated + online LoRouter now uses detailed elevation data, so please check and compare current values if possible. I believe you will be satisfied  ;).

Values on the web are now more realistic. Values are now also united on the web and in the Android app so computed values on all platforms should be identical. So give it a try ...
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Sonny

#5
I tested Online Web Planer using a route which created dramatic wrong values in the past, have a look at: https://help.locusmap.eu/topic/32125-wrong-elevation-in-route-planner
Online Web planer delivers correct values now - great! (btw: what elevation data the online planer is exactally using now?)

But sadly the issue using this example route still exists if using Route planner within LM3 and maybe also within LM4 - althoug exact elevation data is installed.

Menion

Hello Sonny,
thanks for the confirmation it now works as expected.

Route planner: it is probably the same issue we talk about. The app already for some time does not replace! elevation values in computed routes.

It is now even more important. Online and offline LoRouter now uses identical datasets for elevation values (LoMaps contour lines as well) so elevation values in computed routes are always identical or usually better than elevation data users have in devices. So there is no need to recompute elevation values in these cases.

So the only place where it may make sense is GraphHopper and external offline BRouter. Not too many people use them ...
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Sonny

#7
Hi Menion,

- What elevation data exactaly are you using for your LoRouter online? And are these the same files which LM4 useres are downloading for using LoRouter offline?

- A very important advantage of Locus against its competitors has always been its offline skills. Very important when hiking/cycling where no Internet is available or being abroud where Internet is too expensive.

I personally use BRouter in LM3 offline all the time. It delivered the best elevation sums of all apps until about half year ago. Since then LM3 (and maybe also LM4 using Brouter, Graphhopper) changed something to the worse (see linked thread above) and we do not get good elevation sums anymore although we have installed the best elevation files available in Locus "SRTM"-folder (Sonny 1" DTMs).

So our request: please change this behaviour to how it worked in the past, namly on-the-fly use of precise elevation files within "SRTM"-folder to calculate elevation stats when using other route planers (e.g. BRouter) than LoRouter.

Menion

- Official help (ideas, questions, problems): help.locusmap.eu
- Advanced topics, sharing of knowledges: you're here!
- LM 4 Beta download, LM 4 Release download
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