GPSrChive Discussion Forum

Satellite map IGN:

decalage IGN.jpg

Satellite map Google Earth:

decalage Google Earth.jpg

Whether on the IGN and Google satellite map, the track offset is the same. So I consider the Google satellite map to be accurate like the IGN one.

mimichris wrote: ↑Sun Apr 09, 2023 8:07 am Whether on the IGN and Google satellite map, the track offset is the same. So I consider the Google satellite map to be accurate like the IGN one.

Or they are both 'off' by the same amount...



Can you please share a GPX copy of that track?

GPX file link :

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https://mega.nz/file/ZR4FgSAJ#2Cymebg8m ... ubBIWNSDM0

GPSrChive wrote: ↑Sun Apr 09, 2023 12:18 pm
Or they are both 'off' by the same amount...

The satellite photos do not come from the same source, the IGN has its satellites and its planes for the photos.

GPSrChive wrote: ↑Sun Apr 09, 2023 12:18 pm

mimichris wrote: ↑Sun Apr 09, 2023 8:07 am Whether on the IGN and Google satellite map, the track offset is the same. So I consider the Google satellite map to be accurate like the IGN one.

Or they are both 'off' by the same amount...



Can you please share a GPX copy of that track?

Have you studied the trace I sent in the affirmative, have you seen an anomaly.

mimichris wrote: ↑Thu Apr 20, 2023 12:33 pm Have you studied the trace I sent in the affirmative, have you seen an anomaly.

Yes, we did view your track in Google Earth Pro, and moved the 'time slider' to view the track superimposed over many dates back to 2014, and we can see the imagery shift as much as 6 meters.

position of the terminal surrounded by the blue line point a of the IGN document below :

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borne 3418402 tracé Earth.jpg

Point in Earth:

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borne 3418402 Earth.jpg

Point in IGN :

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borne 3418402 IGN.jpg

You can see that the geodetic marker is at the correct coordinates on both Google and IGN satellite maps.

map of the IGN document terminal:

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3418402_001.jpg

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3418402_002.jpg

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3418402_003.jpg

I did not specify, the satellite photos are from Mobac which accurately records the orthos from Google Earth and IGN, there is no offset, if I place the coordinates directly on Google Earth, there is no no lag either.

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Earth.jpg

mimichris wrote: ↑Fri Apr 21, 2023 10:17 am I did not specify, the satellite photos are from Mobac which accurately records the orthos from Google Earth and IGN, there is no offset, if I place the coordinates directly on Google Earth, there is no no lag either.

I 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

I don't agree with you, if you put the mouse arrow on a point (pebbles) of your animation, the pebble is always under the arrow from frame to frame but that's just the change definition that gives this effect, experience it.