How does "fill altitude" work in the background?

Cegam shared this question 6 years ago


today I figured out that "fill altitude" for recorded tracks gives me quite different values for elevation than the recorded values do.

Am I assuming correctly that this is due to a smoothening algorithm in the background?


Replies (2)



there are at least three ways how get elevation to your recorded data:

1. Raw GPS data that are recorded

2. Fill altitude online - Locus use google service for getting elevation data for specified point on the earth

3. Fill altitude offline - Locus download elevation data that cover area about 60x60km. These eleavtion data are in format *.hgt as result of NASA SRTM mission

Altitude from 2. and 3. should be quite similar. But there can be big difference between raw GPS altitude and altitude from 2. or 3. because GPS is not accurate for elevation.

Locus offers some possibilities to improve elevation from GPS. See Menu > Settings > GPS and Location > Altitude correction. More about it is written in

I suggest to enable altitude offset with automatic correction from global Geoid.


Hi Petr,

Thank you very much for your answer. I relied on SRTM

data from NASA and was surprised that Locus Pro calculated different

values from my computer program "GPS-Track-Analyse.NET". ""

generates different values again. After a look in the knowledge base

article you recommended I realize this is an interesting topic with lots

of different approaches. So I assume for planning trips I should rather

stick with the conservative calculations.

Thank you very much for your help and Locus Pro :)

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