altitude measurement unit
- Thread starter paolo negroni
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The GPS vertical position (Civilian band) can be +/- 4 times the horizontal error added to the SV’s via the GPS controllers .
The value of GPS altitude in EXIF data isn't reliable for right position.
The value of GPS altitude in EXIF data isn't reliable for right position.
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Ellipsoid altitude ?
ST16s shows live AGL altitude ( from barometer), but exif of photos (based on GPS) show height above ellipsoid based on WGS84 or alike coordinates. The drone has no idea of the MSL...
You have to have the same coordinates ref in exifs to be able to deduct drone's altitude (AGL)
samples of GPS coordinates referential systems... (WGS84, MN95, MN03,...)
So height of Ellipsoid to ground = EH
Ground to Drone = AGL
Exit height of drone = EH+AGL
My EXIF shows 1046 m which is EH + AGL
My ground is at 1021 m = EH
So my drone is 25m AGL, which is normally shown on the ST16s
ST16s shows live AGL altitude ( from barometer), but exif of photos (based on GPS) show height above ellipsoid based on WGS84 or alike coordinates. The drone has no idea of the MSL...
You have to have the same coordinates ref in exifs to be able to deduct drone's altitude (AGL)
samples of GPS coordinates referential systems... (WGS84, MN95, MN03,...)
So height of Ellipsoid to ground = EH
Ground to Drone = AGL
Exit height of drone = EH+AGL
My EXIF shows 1046 m which is EH + AGL
My ground is at 1021 m = EH
So my drone is 25m AGL, which is normally shown on the ST16s
Exactly, Sarah
@paolo negroni, three posts to get out of nonsense.
1) I live in France so at home the values are the meter and the km / h for the speed ....
So it can not be 460.77 feet or 153.59 m.
Because the TOPO IGN map gives me the GPS location of the photo already 443 meters.
2) This photo took much more than 17 meters from the ground! What do you know? You were there? .The barn is 8 meters high, so feel the height.
FYI, I give you the Exif of the photo and UAV Toolbox flight that confirms my say because at 14:38, the taking of the photo was between 16 and 18 meters from the ground.
So at this precise moment (14:38), I was between 459 and 461 meters.
So, I feel that the H520 GPS is relatively accurate since it gives me in the Exif an altitude of 460.77 meters.
Now, everyone thinks what he wants.
Exif :
flight log :
@paolo negroni, three posts to get out of nonsense.
1) I live in France so at home the values are the meter and the km / h for the speed ....
So it can not be 460.77 feet or 153.59 m.
Because the TOPO IGN map gives me the GPS location of the photo already 443 meters.
2) This photo took much more than 17 meters from the ground! What do you know? You were there? .The barn is 8 meters high, so feel the height.
FYI, I give you the Exif of the photo and UAV Toolbox flight that confirms my say because at 14:38, the taking of the photo was between 16 and 18 meters from the ground.
So at this precise moment (14:38), I was between 459 and 461 meters.
So, I feel that the H520 GPS is relatively accurate since it gives me in the Exif an altitude of 460.77 meters.
Now, everyone thinks what he wants.
Exif :
flight log :
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GPS's altitude can vary +/- 5 m, in photogrammetry you need to tell the software the reference altitude pulled from a known landmark, AND tell the software what elipsoid GPS ref your are working on, if you do so you get a correct +/- 10 cm altitude. With RTK and a beacon, you can reach below the centimeter precision.
There's a dropdown box in ST16 where you can set the ellipsoid ref system in France is ETRS89, set it and you will get it set as for with IGN topo maps.
www.ngi.be
There's a dropdown box in ST16 where you can set the ellipsoid ref system in France is ETRS89, set it and you will get it set as for with IGN topo maps.
Les géodonnées, votre atout géographique - NGI
L’Institut géographique national (IGN) est le gestionnaire des géodonnées au niveau fédéral et geobroker. L’IGN collecte, gère et diffuse les informations géographiques sur la Belgique, sous forme de cartes, photos aériennes et géodonnées numériques. Ensemble, nous examinons les opportunités...
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Thank you, but where is this drop down menu, I have not seen it?
It may be necessary that the H520 is connected to the RC!
It may be necessary that the H520 is connected to the RC!
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Not sure ? let me check that again, anyways by default it is set to WGS84, like most of the GPS'
There are tools in the web to convert from one ellipsoid referential to another.
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