ascent: wildly overestimated

So, I have downloaded all the DEM1 files relating to my area (Switzerland)., But what I find is that OruxMaps overestimates my ascent (during my bike endeavours) by 40-50% over the barometer-based readings of my Polar watch. The Polar watch gets it more-or-less right, not super accurate, but Orux is absolutely off-key! I have tried disabling the "online elevation service" from the settings, but things haven't improved. What may be the issue here? I would be extremely grateful for any advice! OruxMaps is a great piece of software and I am totally addicted to it (and I have donated to the author, of course!).

aag wrote:So, I have downloaded all the DEM1 files relating to my area (Switzerland)., But what I find is that OruxMaps overestimates my ascent (during my bike endeavours) by 40-50% over the barometer-based readings of my Polar watch. The Polar watch gets it more-or-less right, not super accurate, but Orux is absolutely off-key! I have tried disabling the "online elevation service" from the settings, but things haven't improved. What may be the issue here? I would be extremely grateful for any advice! OruxMaps is a great piece of software and I am totally addicted to it (and I have donated to the author, of course!).

Hi,

The GPS is very inaccurate measuring altitudes; OruxMaps averages the values, but there are still problems with some gps; but there are some solutions.

1.-If your device has a barometer, use it to get the altitude, instead of gps (settings - gps).
2.-If you have downloaded alttitude DEM files, use this data instead of the GPS altitude (settings - gps). Better if you check 'interpolate altitudes'.
3.-You can correct after the values ​​of the altitudes of a track using:
a) online services.
b) DEM files.

The 'online elevation service' check is useful if you use a custom service, but does nothing while you are recording a track.

orux

Thank you for your lightning-fast support!!! OruxMaps is the greatest!

So, I have unchecked the "Geoid correction" and now OruxMaps (on a Samsung Galaxy S4) shows the same elevation as the PolarWatch (the discrepancy is <0.4% over a 1000m ascent!). This means that both measurements are precise, even if they are not accurate (since the starting elevation is dependent on atmospheric conditions).

It appears that whenever "Geoid Correction" and "Barometer" are both checked, OruxMaps uses GPS rather than Barometer for determining heights. Does this make sense, if the GPS vertical measurements are much less precise than barometric ones?