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pds-data-dictionaries / PDS4-LDD-Issue-Repo

Issue repository for tracking all PDS4 Discipline Dictionary-related issues, new feature requests, and releases.
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[ldd-img] Aperture #163

Closed KalofXeno closed 3 years ago

KalofXeno commented 3 years ago

Issue Type: ENHANCEMENT

Add a new attribute under img:Optical_Properties:

<img:Optical_Properties>
  <aperture>8.91886</aperture>
</img:Optical_Properties>

Definitions:

Aperture Defines opening through which light passes in an optical instrument. From EXIF, aperture value is noted being displayed as an F number, but stored as an APEX value.

Additional context Example: sqrt(2^(8918863/1000000)) = f/22 = aperture

children: none, unless a description for APEX value and or aperture stop value is warranted.

thareUSGS commented 3 years ago

@KalofXeno Question. How is this different from f_number: https://github.com/pds-data-dictionaries/ldd-img/blob/7e518c226d07c138c5b8be23c87bdfdc6d8d806e/src/PDS4_IMG_IngestLDD.xml#L1626

If different, can you recommend better definition for f_number to distinguish it from aperture.

KalofXeno commented 3 years ago

@thareUSGS After talking with PI of "mission" I think we are good with f_number, exposure_duration, and focal_length. Aperture may not be necessary after all. Perhaps I was concentrating on effective aperture and how it is inversely proportional to f_number (f_number = focal_length / effective aperture).

This issue can probably be closed.

thareUSGS commented 3 years ago

I will close for now, but if you have second thoughts we can reopen. Thanks for digging into it.