I think it is not legit to just screenshot the different timelayers in google earth pro and overlay them. The GPX file contains the precise date and time and google earth pro takes it into account. When I tried to slide the timeline in google earth pro, my gpx track vanished because it was not taken at this time.GPSrChive wrote: ↑Sat Apr 22, 2023 12:00 amI think you may be missing the point.
It does not matter that your choice of satellite imagery matches perfectly with Google Earth satellite imagery because, as mentioned previously, Google Earth satellite imagery does not always agree with Google Earth satellite imagery. Google Earth satellite imagery can shift several meters from one release to the next. So when your data matches Google Earth satellite imagery precisely, it only does so for that release, and will not match other versions of Google Earth satellite imagery that are shifted one way or another.
Please examine these Google Earth Satellite Imagery examples from JAN 2022 and AUG 2022 for the NIZAS II reference point coordinates:
NIZAS II Google Earth Shift
NIZAS II Google Earth 2022-01 2022-08 ANI.gif
Accuracy of a trace
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Re: Accuracy of a trace
- GPSrChive
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Re: Accuracy of a trace
There were no GPX files used for the example provided.Gadwin wrote: ↑Sat Apr 22, 2023 11:27 amI think it is not legit to just screenshot the different timelayers in google earth pro and overlay them. The GPX file contains the precise date and time and google earth pro takes it into account. When I tried to slide the timeline in google earth pro, my gpx track vanished because it was not taken at this time.GPSrChive wrote: ↑Sat Apr 22, 2023 12:00 amI think you may be missing the point.
It does not matter that your choice of satellite imagery matches perfectly with Google Earth satellite imagery because, as mentioned previously, Google Earth satellite imagery does not always agree with Google Earth satellite imagery. Google Earth satellite imagery can shift several meters from one release to the next. So when your data matches Google Earth satellite imagery precisely, it only does so for that release, and will not match other versions of Google Earth satellite imagery that are shifted one way or another.
Please examine these Google Earth Satellite Imagery examples from JAN 2022 and AUG 2022 for the NIZAS II reference point coordinates:
NIZAS II Google Earth Shift
I simply entered the coordinates for the reference point you provided into Google Earth and compared different imagery dates for that location. You can see the coordinates are the same at the bottom of the screen!
You do not have the required permissions to view the files attached to this post.
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Re: Accuracy of a trace
Which proves that the lag that I sometimes have on the tracks does not come from the maps but from the tolerance of the 66sr which is given for +/-3m, which corresponds to my lags, in reality it is very little but we wants it to be perfect....
GPSMAP66sr, GPSMAP67, GPSII+, Twonav Cross.
- GPSrChive
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Re: Accuracy of a trace
Anyone can see the entire map and everything in it shifts from one date to another with the same coordinates selected for the center point.
You must be delusional. I do not care that you are, but we are not going to spread misinformation here.
A quick recap for those having trouble following along:
mimichris wrote: ↑Thu Apr 06, 2023 9:09 am The IGN France maps are very precise, they are used to create IGN maps at 1/25,000, this is the reference and I have exactly the same offset as on Google Earth.
There is a geodesic system in France precise to the cm, we can access the terminals and markers, their positions and their precision.
GPSrChive wrote: ↑Sat Apr 22, 2023 12:00 amI think you may be missing the point.
It does not matter that your choice of satellite imagery matches perfectly with Google Earth satellite imagery because, as mentioned previously, Google Earth satellite imagery does not always agree with Google Earth satellite imagery. Google Earth satellite imagery can shift several meters from one release to the next. So when your data matches Google Earth satellite imagery precisely, it only does so for that release, and will not match other versions of Google Earth satellite imagery that are shifted one way or another.
Please examine these Google Earth Satellite Imagery examples from JAN 2022 and AUG 2022 for the NIZAS II reference point coordinates:
NIZAS II Google Earth Shift
You do not have the required permissions to view the files attached to this post.