Altitude difference

Started by FraMic, August 17, 2024, 20:10:51

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FraMic

Hi all,
I notice altitude value on cursor is not equal to altitude reported on map.
(see attached image)


Why? How can I solve ?

Thank you!!!
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michaelbechtold

1) ele values in OSM are not always correct (neither in Wikipedia - who copies from whom? :-)
2) Locus gets its ele value from stored hgt (SRTM) files. This can be old stuff, or the better LIDAR stuff from Sonny.
3) if you stored a POI in Locus, Locus will get the ele from that position
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FraMic

Hi michaelbechtold,

thank you for your response.

Is there a way to align these values or not ?

Thank you.
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michaelbechtold

The answer differs, depending on root cause:
1) ele values in OSM are not always correct (neither in Wikipedia - who copies from whom? :-)
Someone validate then edit the OSM database; then it will take time until these changes make it into the various maps (LoMaps, OAM, MapsForge, you name it)

2) Locus gets its ele value from stored hgt (SRTM) files. This can be old stuff, or the better LIDAR stuff from Sonny.
Sonny's LIDAR files for Europe are the best you can get; replace the Locus internal downloads manually by those LIDAR files for your relevant areas (mind: 25MB versus 3 MB - each)

3) if you stored a POI in Locus, Locus will get the ele from that position
Depends on #2

Or you can just live with it ... nature itself does not care which values humans attach to its elemens anyway :-)

PS: I do use Sonny's LIDAR 1" HGT files, then trust the Locus display based on them.
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FraMic

Thank you michaelbechtold .

I'll follow your way!

I love Locus Map and I'm excited about the possibilities it offers.

Super top!
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Sonny

#5
For a good first analysis of elevations (in Europe only) you can use "Tracestrack Topo" layer of openstreetmap.org, which relies on precise Sonny 1"-elevation data. But be careful: Just the CONTOUR LINES are bases on Sonny-data. The SPOT-ELEVATION (here: 1001m) are created by OSM-mappers which can be true or not.

For you spot "Glyer Fawr":
https://www.openstreetmap.org/#map=19/53.101561/-4.028662&layers=P
You see that the last contour line near the peak is 990 m, so the spot elevation of the peak with about 1000m is true.

On the other hand the reported "917 m" from locus in your image is false.
Reason: because of the often unacurate elevation model which ist provided by Locus for download (= SRTM 3")
Soltion: download Sonny 1" DTM of UK and install it within Locus' "SRTM"-folder