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Author Topic: WGS84 to ETRS89 datum transformation  (Read 3529 times)

Isaac H. E.

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WGS84 to ETRS89 datum transformation
« on: September 08, 2017, 06:58:38 PM »
Hi,

I believe that as of now PS is only able to apply 7 parameters datum transformation however to consistently transform from WGS84 to ETRS89 it is necessary to input time based parameters (14 parameter transformation).

If I´m correct now PS assumes the datum transformation between WGS84 and ETRS89 as X:0 Y:0 Z:0 rX:0 rY:0 rZ:0 ppm:0 which is acceptable if metric accuracy is sufficient but is not acceptable for survey work (sub centimetre).

Thanks for your time and effort.

Isaac

Yoann Courtois

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Re: WGS84 to ETRS89 datum transformation
« Reply #1 on: September 11, 2017, 12:06:47 PM »
Hi !

There is indeed couple of errors in datum transformations.

From my point of view (France), datum transformations between WGS84 and local system (Lambert CC) are clearly wrong.
And the available geoids are even worse. (Or I clearly use them wrongly...)

For the moment I didn't have to use them but in a near future it could be really needed.

Regards
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Yoann COURTOIS
R&D Engineer in photogrammetric process and mobile application
Lyon, FRANCE
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cadm8

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Re: WGS84 to ETRS89 datum transformation
« Reply #2 on: September 19, 2017, 01:17:31 AM »
Hi,

I believe that as of now PS is only able to apply 7 parameters datum transformation however to consistently transform from WGS84 to ETRS89 it is necessary to input time based parameters (14 parameter transformation).

If I´m correct now PS assumes the datum transformation between WGS84 and ETRS89 as X:0 Y:0 Z:0 rX:0 rY:0 rZ:0 ppm:0 which is acceptable if metric accuracy is sufficient but is not acceptable for survey work (sub centimetre).

Thanks for your time and effort.

Isaac
I suppose you're referring to WGS84 in the context of accurate lat./long coordinates calculated from ie GNSS network? Otherwise there is no 'sub centimeter' WGS84 coordinate

Alexey Pasumansky

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Re: WGS84 to ETRS89 datum transformation
« Reply #3 on: September 19, 2017, 08:44:08 PM »
Hello Isaac,

In the version 1.4.0 you can specify the Datum Transformation Parameters manually (by clicking on the Datum Transformation Settings button in the Reference pane settings dialog).
Best regards,
Alexey Pasumansky,
Agisoft LLC