ExifTool Forum

ExifTool => Newbies => Topic started by: Lùrenz on April 13, 2024, 05:19:57 AM

Title: Offset GPS altitude metadata
Post by: Lùrenz on April 13, 2024, 05:19:57 AM
Hi everybody, i would like to ask some advice on how to change some specific data (GPS altitude and altitude reference) in a set of pictures took with my dji drone, if it's possible I would prefer to offset all those values to obtain a quite precise elevation instead of setting the same altitude for all images to prevent the flattening of the entire dataset.
Title: Re: Offset GPS altitude metadata
Post by: Phil Harvey on April 13, 2024, 08:31:14 AM
For example, to subtract 20.5 meters:

exiftool -gpsaltitude+=-20.5 DIR

- Phil
Title: Re: Offset GPS altitude metadata
Post by: StarGeek on April 13, 2024, 09:49:07 AM
The relevant part of the documentation under the -TAG[+-^]=[VALUE] option (https://exiftool.org/exiftool_pod.html#TAG---VALUE)

Quote+= may also be used to increment numerical values (or decrement if VALUE is negative),

Note that to subtract, you have to "add" a negative number as in Phil's example.  That's because -= is a different operation. Directly after the above documentation is

Quoteand -= may be used to conditionally delete or replace a tag
Title: Re: Offset GPS altitude metadata
Post by: Lùrenz on April 13, 2024, 05:21:36 PM
Thank you!