Author Topic: Exporting GPS data as GPX from Garmin 66W DashCam  (Read 1719 times)

Vassy

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Exporting GPS data as GPX from Garmin 66W DashCam
« on: October 24, 2019, 12:20:31 PM »
Hello. I'm struggling export GPS data from Garmin 66W Dash Cam. I managed to export the attached file using exiftool -ee a.MP4 > out

I can see in the file a lot of GPS data. The only problem I have now is that I don't know go to convert the file I got to GPX.

Thank you in advice.

StarGeek

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Re: Exporting GPS data as GPX from Garmin 66W DashCam
« Reply #1 on: October 24, 2019, 12:24:17 PM »
See Inverse Geotagging.

First, you need to create the gpx.fmt file listed there or download it from Github.  Put it in the same directory as exiftool.  Then run the command listed there.
exiftool -p gpx.fmt -ee a.MP4 > out.gpx
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.

Phil Harvey

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Re: Exporting GPS data as GPX from Garmin 66W DashCam
« Reply #2 on: October 24, 2019, 12:49:15 PM »
You will be able to make a KML file like this, but not a GPX file because the telemetry lacks a GPS date/time.

It is possible to generate a GPSDateTime tag from CreateDate and SampleTime, but it won't accurate to better than 1 second.  The attached config file will allow you to do this.  Here is the command:

exiftool -config gpsdatetime.config -p gpx.fmt -ee a.MP4 > out.gpx

- 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 ($).

Phil Harvey

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Re: Exporting GPS data as GPX from Garmin 66W DashCam
« Reply #3 on: October 24, 2019, 01:04:22 PM »
Hmmm.  The distributed version of gpx.fmt doesn't preserve sub-seconds in the GPSDateTime value, which will further degrade the timestamp accuracy.  Attached is a new version that supports this.

- 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 ($).

Vassy

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Re: Exporting GPS data as GPX from Garmin 66W DashCam
« Reply #4 on: October 24, 2019, 04:27:38 PM »
Ok. So. I'm looking for reported speed by the camera which is the correct one. The speed calculated by time and distance is not correct.

There is already a piece of software made by Garmin called Garmin Dash Cam Player which allows you to export GPX from the MP4 file.
The problem is that is exporting only lat, long and time. As you can see in my attached file (out), the file also contain the speed in mph.

As you can see here, GPX supports a tag called speed, which must be in meters per second. I don't think would be a problem to convert miles per hour to meters per second.

Using the commands from above, I managed to export a GPX file which includes the speed tag.

The big problem is that, Virb Edit, the software I tried to use to add the Speed overlay, is not supporting the speed tag from GPX at all, so all this research was for nothing. Well, at least I heard of this tool, which is amazing, I can't believe how much work was put into it and how smart are the people working on it.

A second option would be to use a .fit file. From that file Virb Edit can take advantage of the recorded speed within the file. Did you have any idea if it's possible to convert a GPX file which has the speed tag to a fit file? I tried this website but it doesn't convert the speed, only route.

Also, if you know a GPS Video Overlay software which can take advantage of the speed tag of a GPX file, let me know.

Thank you for help.
« Last Edit: October 24, 2019, 04:38:07 PM by Vassy »

Phil Harvey

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Re: Exporting GPS data as GPX from Garmin 66W DashCam
« Reply #5 on: October 24, 2019, 05:23:15 PM »
I'm afraid that you have just passed beyond my realm of expertise.  I don't know much about other software.

- 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 ($).