Author Topic: Problem of false altitude when creating a trace in Italy ?  (Read 335 times)

Offline madimax

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Hello,
I was in Italy last week and I made a gpx trace in "auto mode".(see attached file)
The trace is correct but the altitude was incorrect : do you see any reason ? (the total positive elevation is about 30 times too high ... , as if it was generated in feet and not in meter ??)
Thank's for your return
Emmanuel
 

Offline michaelbechtold

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Re: Problem of false altitude when creating a trace in Italy ?
« Reply #1 on: July 24, 2019, 02:43:28 »
I looked at the track in Google Earth and most of the route it seems just fine.
But then your track "climbs" extremely steep summits in nearly flat hilly areas, summits that simply do not exist.
Do you record the NMEA files (GPS raw data) in Locus ?
 

Offline madimax

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Re: Problem of false altitude when creating a trace in Italy ?
« Reply #2 on: July 25, 2019, 09:05:17 »
Hi Michael,
Thanks for your quick reply.
No I don't record NMEA file !
I just come back at home yesterday and make 2 simple traces (see attached files)
  • one is created with locus pro
  • the other with gpsies
You will see the big difference between them about altitude ! (and the right one is thes gpsies, for I walk there !)
Best regards
Emmanuel
« Last Edit: July 25, 2019, 09:09:21 by madimax »
 

Offline michaelbechtold

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Re: Problem of false altitude when creating a trace in Italy ?
« Reply #3 on: July 25, 2019, 10:34:21 »
Good approach, Emmanuel.
That will be an interesting challnge for Menion then :-)
Cheers
Michael
 

Offline lor74cas

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Re: Problem of false altitude when creating a trace in Italy ?
« Reply #4 on: July 25, 2019, 12:37:51 »
I imported the track in locus pro, the altitude values were completely wrong.
Always in locus I applied the altitude correction for the track based on the srtm files and the result gave +571 -1457.
What settings did you use for the altitudes in the locus and do you use the srtm data?
 

Offline menion

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Re: Problem of false altitude when creating a trace in Italy ?
« Reply #5 on: July 25, 2019, 15:03:37 »
Hello, the "essai_locuspro.gpx" is really nice. I do not remember to saw track with such completely wrong elevation. Can't imagine what happens ...
You may post here a screenshot of the first screen of altitude manager. Also, I highly suggest trying to record a track with different application to exclude possible hardware malfunction of your device. Thanks.
Ideas, wishes, problems
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Offline madimax

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Re: Problem of false altitude when creating a trace in Italy ?
« Reply #6 on: July 26, 2019, 23:20:37 »
about : "What settings did you use for the altitudes in the locus and do you use the srtm data ?"

I am sorry, but I never parameter anything about altitude, and I don't know where to verify this srtm data ??
I create more than 50 traces with locus pro in France and I never get any trouble; my first problem comes when I create a trace in Italy.
When I write "create a trace", it means to create with "Route planning" before walking ...
where can I find some info about it ?
Thank's for your help.
Emmanuel
 

Offline menion

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Re: Problem of false altitude when creating a trace in Italy ?
« Reply #7 on: July 29, 2019, 09:13:41 »
Hello, oki so "essai_locuspro.gpx" you shared before was made in Locus Map with "Route planner" function?
Then seems you have incorrect height data. Did you manually downloaded HGT files into Locus/data/srtm directory? Suggest deleting file N46E012.hgt in mentioned directory. Then use "Update elevation" function from the bottom menu in track detail. The app should offer download of missing HGT file and then fill correct elevation values.
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Offline madimax

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Re: Problem of false altitude when creating a trace in Italy ?
« Reply #8 on: August 05, 2019, 23:27:55 »
The problem is solved with downloading the new elevation file : thank's for your reply
Emmanuel :)
 

Offline menion

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Re: Problem of false altitude when creating a trace in Italy ?
« Reply #9 on: August 06, 2019, 19:06:16 »
Hello, perfect. I just made a small improvement in the app that when it detects invalid (based on its size) HGT file, it won't use it and suggest to re-download it. Hope it will help to detect such files.
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Offline madimax

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Re: Problem of false altitude when creating a trace in Italy ?
« Reply #10 on: August 14, 2019, 15:07:19 »
thank's very much  :)
Emmanuel