Author Topic: Differing GPS Data  (Read 1776 times)

aaronTL

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Differing GPS Data
« on: May 03, 2016, 02:44:40 AM »
Hi All

Please excuse me for barging in here and asking questions immediately. If this is inappropriate, please delete.

I have two images that show:
GPS
GPS Latitude Ref
South
GPS Latitude
36.916367 degrees
GPS Longitude Ref
East
GPS Longitude
174.840850 degrees
GPS Altitude Ref
Below Sea Level
GPS Altitude
0.7496337891 m
GPS Time Stamp
20:14:24
GPS Speed Ref
km/h
GPS Speed
N/A
GPS Img Direction Ref
True North
GPS Img Direction
75.62679426
GPS Dest Bearing Ref
True North
GPS Dest Bearing
75.62679426
GPS Date Stamp
2016:04:27
GPS_0x001f
10

AND:

Make
Apple
Model
iPhone 6s Plus
Aperture
2.2
Exposure Time
1/17 (0.0588235294118 sec)
Focal Length
4.2 mm
Flash
Auto, Did not fire
File Size
971 kB
File Type
JPEG
MIME Type
image/jpeg
Image Width
2016
Image Height
1512
Encoding Process
Baseline DCT, Huffman coding
Bits Per Sample
8
Color Components
3
X Resolution
72
Y Resolution
72
Software
9.3.1
YCbCr Sub Sampling
YCbCr4:2:0 (2 2)
YCbCr Positioning
Centered
Exposure Program
Program AE
Date and Time (Original)
2016:04:28 08:14:24

Can anyone advise why the date/time from the GPS data differs from the date/time of the other data? Can this change by itself or would it have been modified?

Thanks for your time.

StarGeek

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Re: Differing GPS Data
« Reply #1 on: May 03, 2016, 03:37:05 AM »
The difference in time should be the same as your time zone difference.  GPS timestamps are set for +0 UTC.
Troubleshooting hints:
* When posting, include your OS, Exiftool version, and type of file you're processing (MP4, JPG, etc).
* Double all percent signs (%) in a Windows batch file.
* If your GPS coords are negative, make sure and set the GpsLatitudeRef and GpsLongitudeRef tags correctly.

aaronTL

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Re: Differing GPS Data
« Reply #2 on: May 03, 2016, 03:11:12 PM »
Thanks StarGeek, so me being in New Zealand, the timestamp on the GPS data should be -12 hours from the timestamp for the create date?

Phil Harvey

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Re: Differing GPS Data
« Reply #3 on: May 03, 2016, 03:32:40 PM »
I'm wondering if ExifTool should add a "Z" to the time to make this more clear.  (I wonder what this would break though.)

- Phil
...where DIR is the name of a directory/folder containing the images.  On Mac/Linux, use single quotes (') instead of double quotes (") around arguments containing a dollar sign ($).

Alan Clifford

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Re: Differing GPS Data
« Reply #4 on: May 03, 2016, 06:28:11 PM »
I'm wondering if ExifTool should add a "Z" to the time to make this more clear.  (I wonder what this would break though.)

- Phil

Then the questions would become, "What does Z mean?"  Which is quite legitimate if you are not familiar with all the terminology.


Phil Harvey

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Re: Differing GPS Data
« Reply #5 on: May 04, 2016, 07:36:44 AM »
Then the questions would become, "What does Z mean?"  Which is quite legitimate if you are not familiar with all the terminology.

Right.  Better leave it alone.  I did however add a note in the tag name documentation to make it clear this is a UTC time.

- Phil
...where DIR is the name of a directory/folder containing the images.  On Mac/Linux, use single quotes (') instead of double quotes (") around arguments containing a dollar sign ($).

StarGeek

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Re: Differing GPS Data
« Reply #6 on: May 04, 2016, 12:52:59 PM »
Thanks StarGeek, so me being in New Zealand, the timestamp on the GPS data should be -12 hours from the timestamp for the create date?

That sounds about right.
Troubleshooting hints:
* When posting, include your OS, Exiftool version, and type of file you're processing (MP4, JPG, etc).
* Double all percent signs (%) in a Windows batch file.
* If your GPS coords are negative, make sure and set the GpsLatitudeRef and GpsLongitudeRef tags correctly.