Some doubts about track recording

Andrea Arcangeli shared this question 2 months ago
Answered

Dear all,


I am a new user of Locus Map 4; I like it very much but before upgrading I wanted to do some testing. Yesterday I went trekking and did a recording. There were some issues in the recording I'd like to understand:

- First of all, there were some jumps in the track recording. Why is that?


- The most painful issue is the recording went wrong sometimes as for the elevation values. It would suddenly drop to the elevation of the starting point. How can I avoid this? In practice I removed afterwards the wrong points and reconnected creating new points, but this is a time-consuming process I'd like to avoid

- Another big issue, related to the above, is that the final point recorded a wrong elevation. The final point was more or less the same than the starting point, but it gave a wrong elevation. Therefore, even if I tried to remove the end part of the track to recreate it, I had all the final part of the track always reset to the wrong final elevation. How can I force recalculation of the point according to real track elevation?

Thanks in advance

Replies (8)

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A possible solution for your first problem can be found here and here.

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An user (whom I thank a lot) suggested me to address the first topic with the following:

- system settings for location permission (I had already set it to "allow all the time")

- system settings for battery optimization (I had already excluded Lotus map from optimizations)

- Locus settings for "disable location" (I had "disable when app hidden" ON, "GPS ON for track recording" OFF and "GPS ON for guidance" ON. I precise that I started recording and guidance more or less at the same time. Sometimes I paused track recording for resting, but I don't remember ever having stopped guidance during pauses.


So you think this could solve the first issue? Simply setting GPS ON for track recording?


Anyway the other issues remain unsolved, because they didn't emerge during pauses. Could they be caused by GPS satellite switching? Looking forward for a solution.

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Compared with my GPS-settings in LM4 you should set 'Disable when app is hidden' to OFF and 'GPS ON for track recording' to ON.

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I often experience wildly wrong elevation at the start or during a pause/ unpause during track recording. This is with a built in pressure sensor. I've had a few discussions with the developer, but no simple solution other than to manually delete those clearly invalid points (if this is important to you, generally for me it's not but just annoying on the elevation chart). My only workaround it A) don't auto-start track recording, instead wait a few minutes after GPS is stable then manually start B) reenable GPS a few minutes before unpausing.

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Maype this tips helps to improve altitude / elevation measurement in LM4.

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With the Pressure Sensor> On - may cause elevation "spikes" in my experience: when the GPS first starts, or has been re-enabled after disable during track recording pause to save battery power, the first few elevation measurements can be wildly in error, 10's or 100's metres wrong. If possible do not enable track recording for a few minute to allow the GPS and/or pressure sensor to stabilize. Why the GPS is related to the "independent" pressure sensor, I don't know, but certainly with my 2017 Samsung A520 phone, this is my workaround.

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Hi Andrea,

Locus Map processes elevation gain from the data it receives from your phone GPS. If the data are incorrect or contain huge deviations, then the resulting elevation gain is also incorrect. Locus Map, however, offers a few methods on how to limit these deviations. Open Locus settings > GPS&sensors:


- Location filter > select medium or heavier filter


- Google Services assisted location > turn it ON


- Altitude manager > settings tab > SRTM data - select "Optimize GPS values" or "Replace GPS values"


- Altitude manager > settings tab > Pressure sensor > turn ON (if available)


- Altitude manager > settings tab > Altitude filter - select medium or heavier filter

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First of all thank you all who responded to the question.


I think I need to state more precisely that in my case it was not a matter of wild swings of elevation, such as a fuzzy chart, maybe because I already had the altitude filter set to light. Now I also set the position filter following your suggestions.


My issue was that in a few occasions the altitude would suddenly drop to the value of the starting point, then rapidly swing back to the correct value.


So my understanding is that for some reason the GPS didn't stabilize yet after resuming of the track recording or, given that sometimes the issue appeared when I was simply walking and not during pauses, that for some reason the device lost GPS connection. Therefore maybe the software's reaction should be that if no elevation reading is available, it reverts to the elevation of the previously recorded point with data and not to the first point in the track. This perhaps could be a suggestion for the free version where no alternative altitude readings are available (e.g. no pressure sensor on the smartphone), I don't know... let the developers decide!


Anyway, considered that I found myself quite well with the functions of the app, I decided to try the Silver subscription and indeed, by using the "Update elevation" function (not available in the free version) and SRTM data I managed to fix the elevations in the recorded track and, as per your suggestion, I suppose it would also avoid the spikes in the first place during recording (will try next time). And I would also pay more attention to GPS being correctly stabilized before resuming recording.


Thanks again

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