[closed] Track Recorder shows double Gain/Loss in Elevations 2.2.7c

[grayskull]

This has been a bug previously, and fixed previously, but it's back again. Track recorder gain/loss was recently working correctly on my Xperia XZ1, until I updated to 2.2.7c just now. All recorded tracks are showing double the gain/loss and calories are also doubled compared to when they were recorded.

[Psyberia-Support]

Hi,
I'm not aware of any previous or current bug with the gain computation. But if you believe so please send me some figures or an example track file.
The gain is the altitude difference between all locations, there is no extensive computation, you can easily check the value: export the track in CSV format, open it with excel and make the computation.

What is possible is that your GPS does report unprecise location elevations, that can increase the computed gain, but this is not a bug (see here).
You can also check this easily by looking at the elevation profile.
In order to deal with unprecise elevations, the application does have a noise reduction engine, which you can control with option 2 here: https://www.alpinequest.net/en/help/v2/ ... s_settings.

[grayskull]

Hi, thanks for the suggestions. I did a CSV export for a recent track, opened in Excel, calculated the difference between present and previous elevation for each row, then used SUMIF>0 for gain, SUMIF<0 for loss. Here is a summary:

CSV export gain / loss calculation: +308m / -298m
Track Recorder no noise reduction: +308m / -298m
Track Recorder med noise reduction: +171m / -162m
Track Recorder high noise reduction: +146m / -137m
Actual gain / loss from Google map: +95m / -95m

Having seen this, I changed the noise reduction setting from Medium (default) to High, as that seems to work best. I had seen this issue with a previous update, though I don't recall which one. Maybe to fix that I had set NR to High. Perhaps the latest update defaulted it back to medium, making the gain/loss numbers look greater than they were before the update.

The barometric pressure setting is checked by default in the settings, but the CSV export (from before updating) has no data in the pressure column. Maybe I had previously turned that off to save battery, though I don't recall. My phone (XZ1) has a working pressure sensor. Would it reduce the elevation variance and improve accuracy if barometric pressure could be made to work?

[Psyberia-Support]

Hi again,

Thanks for having checked the figures, I think it's the best way to understand what the application is actually doing and where the results come from.

However, an "error" you make is to assume that the "Actual gain / loss from Google map" is the reference (and correct) gain. This is not the case, as this gain is much smaller than the reality.
If you want to get this gain in the application, you can: be sure to have turned on the elevation data, then manually draw your path and check the gain. It will be similar.
But here we talk about the "estimated" gain, based on lower resolution data gathered from satellites. It's different from the gain effectively recorded on the field, which takes into account every details of the terrain. So naturally, it's much larger... The "real" value, is something between both.

Concerning the barometric elevations computed from the pressure sensor, yes they give much better results. If it's turned off now, maybe this is why you got higher values recently.
Be sure to turn this option in the track recorder settings (so it records pressure values during your track), and also on the stats settings (so the stats use those elevations instead of the GPS elevations). Note that the pressure sensor does consume very little battery.

[grayskull]

Hi, thanks for the update. I've enabled "record pressure values" in track recorder settings (it was unchecked) and I'll see how it goes.

[grayskull]

Hi, the track recorder seems to work better with barometric pressure enabled. Thanks for your help.