gpx interpolation?

Last month I flyed across the Atlantic Ocean, and took some photo, recording the gpx with OSMAnd in order to geotag the photos. Unfortunatly, the airplane isn’t transparent to gpx satellite signals, so my gpx file only took the points before and after my stay inside the airplane.

The photos were taken in the middle of the ocean, and I expected that importing the gpx into darktable geotagging module I’d get the photos position by interpolation. On the contrary, darktable assigns my photo to either the last point before entering the airplane or the first after exiting from it.

Is it ok or am I missing something?

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You are correct, that is the way it works today.
I agree that would be better to interpolate. Should be possible.

If you place your GPS tracker next to a window you usually get a very good signal.
But: depending on your device and the chip inside and the height and speed of the plane the signal will not be shown or recorded. Something-transcontinental-missile-something military blablabla. Whoever made up those rules must have been like super crazy paranoid. Hence some chips/receivers ignore them and happily record even fast and high flying planes.

I wrote some years ago a Lua script to interpolate the GPS position with the help of date/time in the images. I’m not sure if it still works or if it works with geodata imported from an gpx file, but perhaps it helps. Have a look at the geoToolbox Lua script:

Nice, but that linear interpolation works as an approximation only for very short distances between points.

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And airplanes don’t even fly the shortest route or at a constant speed. But I think it’s better than the start or end point.

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Sure, but the geodesic one should still get you closer…

Patches are welcome. :wink:

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