ExifTool Forum

General => Metadata => Topic started by: TimA on October 11, 2024, 07:09:34 PM

Title: GPS Img Direction+iPhone+Compass app
Post by: TimA on October 11, 2024, 07:09:34 PM
Anyone able to explain why the exif data is opposite the expected Magnetic North vs Use True North set reference for the Compass app?
When I have it set to True North the exif data shows Magnetic North and vice versa.

GPS Img Direction & Direction Ref.jpg
Title: Re: GPS Img Direction+iPhone+Compass app
Post by: StarGeek on October 11, 2024, 07:38:05 PM
I assume this is an Apple app? You would have to ask them. That said, Apple is well known here for ignoring/not reading standards, including their own.
Title: Re: GPS Img Direction+iPhone+Compass app
Post by: TimA on October 13, 2024, 02:46:19 PM
I assume this is an Apple app?

Compass.app is bundled with iPhone. Settings command of iPhone invites asserting Magnetic North or True North as active.

* Did you read FAQ #3 and use the command listed there?
Only focussing GPSImgDirectionRef

* Please use the Code button for exiftool code/output.
No idea where that is.
 
* Please include your OS, Exiftool version, and type of file you're processing (MP4, JPG, etc).

Mac OS10.13.6,  Exiftool V 12.98   JPG image
Title: Re: GPS Img Direction+iPhone+Compass app
Post by: StarGeek on October 13, 2024, 06:31:38 PM
The details below the horizontal bar is my .sig (https://en.wikipedia.org/wiki/Signature_block) which wasn't specifically directed at you. It's just general, useful information that often helps with troubleshooting. It appears at the bottom of every one of my posts.

And the code button is directly above the text field. But since you weren't posting any exiftool output, it isn't needed.
firefox-2024-10-13_15.18.28.png

If you want to double-check the values that the app is writing, you can add the -n (--printConv) option (https://exiftool.org/exiftool_pod.html#n---printConv).
exiftool -G1 -a -s -n -GPSImgDirectionRef -GPSDestBearingRef file.jpg

The raw values should either be "T" (True North) or "M" (Magnetic North)
Example output
C:\>exiftool -all= -P -overwrite_original -GPSDestBearingRef="Magnetic North" -GPSImgDirectionRef="True North" y:\!temp\Test4.jpg
    1 image files updated

C:\>exiftool -G1 -a -s -n -GPSDestBearingRef -GPSImgDirectionRef y:\!temp\Test4.jpg
[GPS]           GPSDestBearingRef               : M
[GPS]           GPSImgDirectionRef              : T
Title: Re: GPS Img Direction+iPhone+Compass app
Post by: TimA on October 14, 2024, 01:19:55 AM
Well, just have to lay the error at Apple's feet.