Author Topic: Map Panel: GPS Track log functionality. Prefer "Date Subject Created"  (Read 268 times)

Asgard

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Currently the "Create Date" is used to fetch an image's position from the GPS tracklog, with the "Date Subject Created" as a fallback. This is documented in the help system. To me it seems more logical to favor the "Date Subject Created", since the location of the image should be from when the image was taken, not when the file was produced by a RAW editor, scanner or whatever.

If there is a good reason for the current behavior, could the proposed prioritization be an option?


Mario

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Re: Map Panel: GPS Track log functionality. Prefer "Date Subject Created"
« Reply #1 on: September 15, 2021, 09:51:49 PM »
I don't follow. Where did you read that?
It's maybe 2 or 3 years that I worked on that, it's functioning ever since. No problem reports or change requests, ever.

A track log always contains the date and time the track point was created, which maps directly to the image creation time as recorded by the camera.

The date subject created usually only differs from the create date when you digitize old images (scanner....) or when you later manually enter a subject create date.
When you take images with a digital camera, these timestamps are always identical.
IMatch uses it only as a last resort fallback when mapping track logs to digital images.

Asgard

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Re: Map Panel: GPS Track log functionality. Prefer "Date Subject Created"
« Reply #2 on: September 16, 2021, 08:23:08 AM »
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I don't follow. Where did you read that?

The Imatch help says:
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In order to match your track log with your files, IMatch compares the GPX timestamps with the 'created' time stamps in your files (EXIF datetime created, if this does not exist, EXIF datetime digitized).
which also agrees with what I see IMatch does. Although I assume IMatch works with the database values rather than EXIF fields directly - for example, the track log function considers time zone data in the "Create Date" which is not present in embedded Exif if I understand correctly.

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It's maybe 2 or 3 years that I worked on that, it's functioning ever since. No problem reports or change requests, ever.
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The date subject created usually only differs from the create date when you digitize old images (scanner....) or when you later manually enter a subject create date.
When you take images with a digital camera, these timestamps are always identical.

My case is an edge case that doesn't occur often since 99% of all uses of the tool probably deal with images straight from the camera.

I have a set of images given to me by another person, where images have been edited such that there is a new "Create Date" in the Exif data. I can see that this may be an incorrect use of metadata, but it also seems logical that if an image is exported, the "Create date" would change and the "Date Subject Created" would remain the same. But perhaps not the embedded EXIF fields, only XMP or ITPC?

The other reason I ran into issues was that some files given to me have been stripped of Date fields for some reason. For those fields I have manually set "Date Subject Created" and left the "Create Date" as is (taken from the file system meta data). This is according to the logic described in the Help:
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The Date Subject Created is the more important timestamp and when you set or change it, IMatch updates File.DateTime from the new value automatically.
It would make sense to me that the track log tool uses the same date information as the file viewer does when sorting according to Capture Time.

Both cases can be solved with the existing track log functionality by simply copying the "Date Subject created" to the "Create Date" field. However, I argue that track log functionality should always prefer "Date Subject Created" to also cover for the small fraction of cases when these two fields differ. Now it is the other way around.

It is also entirely possibly that I have misunderstood the meaning of the two fields, but I have tried to follow the documentation. Again, this is an edge case and I understand that you hesitate to change what is working for most. I can work with the current implementation but it would be better for me, and I think correct to do it the way I propose.


Mario

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Re: Map Panel: GPS Track log functionality. Prefer "Date Subject Created"
« Reply #3 on: September 16, 2021, 02:50:35 PM »
I prefer mapping the "created" timestamp in the track log to the "created" timestamp of the digital image.
This just worked for so long and I don't see a need to change this to cover on edge case of one user.
Feel free to add a feature request in the feature request board. If a number of other users also considers this a problem or a useful option to have for the map import (in addition to the ability to shift the timestamps anyway), I will learn that and consider this for a future update.

Date created refers to the creation time of the digital image - to it maps neatly to the creation time of the POI or track point.
This usually does not change when you produce a new version of the file (e.g. a RAW => JPEG). The original image was still created on that day. That you  have converted it or saved it in a different format etc. does not matter. When a new image is created, it should get a new set of (usually matching) create date and date subject created.
Date subject created may differ only when the image date created is newer than the actually "motive". For example you scan an image from 1960 in 2021. The data subject created then refers to the the 1960 date, and the date created to the 2021 date.

Asgard

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Re: Map Panel: GPS Track log functionality. Prefer "Date Subject Created"
« Reply #4 on: September 16, 2021, 05:00:47 PM »
I still think "Date Subject Created" is a better choice for mapping against a GPS track log, since
  • in most cases it would work just as the current implementation
  • for the rare case when "Date Subject Created" and "Create Date" do differ, GPS tracklog would work as expected
  • the function would be more consistent with how date/time is used in other places in IMatch
As there is rarely any reason to not assign the same value to "Date Subject Created" and "Create Date", this feature suggestion has lost some of its relevance to me, but I still think it would be a useful improvement.

Since this thread is a feature change request already, I suppose we can let it live for a while and see if someone thinks it is worth considering to
Add an option to use "Date Subject Created" for GPS tracklog matching.

Let me know if I should post the reformulated feature change request as a new thread.