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MartinC_Photos
MartinC_Photos
Known Participant
March 20, 2025
Answered

GPS and time changed slightly after uploading to Adobe Cloud

  • March 20, 2025
  • 1 reply
  • 206 views

Scenario: Away from home I take a load of holiday photos and upload them onto my Adobe Cloud account. I edit them in LR Mobile on my iPad. Back home I synch my LrC (Classic) and I see all my images in LrC. The images all have the correct GPS data and time log (both taken from 5DMkIV).  All good so far. 

But I know that there are additional images on my camera CF card that I didn't import or deleted from the Cloud, so, back home, I then import from the CF card to LrC ensuring that "new images" only is checked.

Problem: LrC imports ALL images adding a "-2" to the file name. So why are the same images not recognised as the same file?  Is it because the the time and GPS are slightly different? And why are they different? The difference is miniscule: 16° 45'38.004" W on CF card and 16° 45'38.0052" W on Cloud version - so not even a rounding error. TIme is 07:41:25.30 on CF card and 07:41:25 on Cloud version.

I don't care about any GPS or time error as it's is too small to worry about, but I don't want to have to go through the imported files removing duplicates. 

Not sure whether the time/GPS error is causing the files to appear as different in LrC.

 

LrC 14.2 on Sequoia 15.3.1 and LR mobile 10.2.2 on Ipad

 

Correct answer johnrellis

Are the cloud and card versions of the photos slightly different in byte size? That would be the most straightforward explanation of why LR Classic Import views them as non-duplicates.  

 

Import determines files are duplicates if they have the same file size in bytes, the same capture date/time, and the same file name.

 

"TIme is 07:41:25.30 on CF card and 07:41:25 on Cloud version."

 

A bug in the sync from LR Mobile clients to LR Cloud truncates fractional seconds of capture time:

https://community.adobe.com/t5/lightroom-classic-bugs/p-quot-save-metadata-to-file-quot-overwrites-exif-tag-subsectimeoriginal/idc-p/14825569#M56293

 

"16° 45'38.004" W on CF card and 16° 45'38.0052" W on Cloud version"

 

The EXIF standard represents a GPS coordinate as a rational number (integer divided by an integer). The standard allows the recording camera/app to choose different denominators. It's likely that LR Cloud is importing the GPS coordinate, converting it to a floating-point number, then reconverting it back to a rational number (perhaps with a different denominator) when saving back into the photo and transmitting to LR Classic. This would account for the minor difference.  

 

But Import's duplicate detection doesn't consider GPS coordinates.

 

 

1 reply

johnrellis
johnrellisCorrect answer
Legend
March 21, 2025

Are the cloud and card versions of the photos slightly different in byte size? That would be the most straightforward explanation of why LR Classic Import views them as non-duplicates.  

 

Import determines files are duplicates if they have the same file size in bytes, the same capture date/time, and the same file name.

 

"TIme is 07:41:25.30 on CF card and 07:41:25 on Cloud version."

 

A bug in the sync from LR Mobile clients to LR Cloud truncates fractional seconds of capture time:

https://community.adobe.com/t5/lightroom-classic-bugs/p-quot-save-metadata-to-file-quot-overwrites-exif-tag-subsectimeoriginal/idc-p/14825569#M56293

 

"16° 45'38.004" W on CF card and 16° 45'38.0052" W on Cloud version"

 

The EXIF standard represents a GPS coordinate as a rational number (integer divided by an integer). The standard allows the recording camera/app to choose different denominators. It's likely that LR Cloud is importing the GPS coordinate, converting it to a floating-point number, then reconverting it back to a rational number (perhaps with a different denominator) when saving back into the photo and transmitting to LR Classic. This would account for the minor difference.  

 

But Import's duplicate detection doesn't consider GPS coordinates.

 

 

    MartinC_Photos
    MartinC_PhotosAuthor
    Known Participant
    March 21, 2025

    Thank you @johnrellis - that's very helpful.

    The cloud and card versions have identical byte size. So, if, as you say, "Import determines files are duplicates if they have the same file size in bytes, the same capture date/time, and the same file name", then my conclusion is that when I'm importing from the card into LrC, it's comparing the card version (which has the correct time) to the version already brought in from the Cloud (with the truncated time) and that is why LrC ends up with two version of the same file. 

    I'm going to have to come up with an alternative return-from-holiday workflow. I'm kind of surprised that this time bug hasn't been fixed. Sounds simple but admittedly I know nothing about how these things work. Thanks again.

     

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