on 08-03-2020 06:40 PM
I am using goprotelemetryextractor.com to extract telemetry data, but I can find no defintions. I appologize if this is a dumb question, I have tried searching.
Ultimately I want to know the orientation of the camera relative to the velocity vector.
The "Camera oriention" has four fields, labeled "CameraOrientation" , "1", "2", "3". If I rotate the camera with me stationairy, through pitch, roll and yaw, I can see 1,2, and 3 going from -1 to 1, which make sense. ...but what are the units?
I thought I needed multiply by 180 to get them in units of degrees. But when I went driving in a car, it showed pitch changing from -30 to 60 degrees, where it should have been in the single digits.
I then though the 1,2,3 was a unit direction vector, but the Norm of the 1,2,3 vector does not equal unity. Are they relative to the gravity vector?
Thanks in advance for any help,
Tim (GoPro Rookie)
on 08-04-2020 02:08 PM
The reason there are no definitions is the camera can potentially record any type of data, and is also able to label the data so that it is self-explanatory, but that's not the case with the orientation streams, generally. The components are just labelled "CameraOrientation" , "1", "2" and "3" precisely because the camera does not label them, so the extractor just gives them numbers so they can be identified.
According to GoPro ( https://github.com/gopro/gpmf-parser#hero8-black-v12-adds-removes-changes-otherwise-supports-all-her... ) that stream is expressed in quaternions. I personally find them very complicated, so here's some background on what they are: https://youtu.be/d4EgbgTm0Bg
Finding out the orientation of the camera relative to the velocity involves some challenges. You could also use a combination of the gyroscope and the accelerometer sensors. Anyway, it will be interesting to see your progress, so feel free to post updates here.
on 08-04-2020 02:24 PM
Ohhhhh Quanternians----I shoulda thought of that. My first clue should have been 4 values instead of 3. Thanks !!!
I love that video.
Yes, I plan on playing with all the telemetry (gyro, accels, etc). Camera oreientation is the one that I found the most interesting... so I started with that one.
Thanks so much for your help.
on 06-16-2021 11:06 PM
GoPro 9 vibration animation was created using extracted metadata. The below video was uploaded in Japanese, but you can easily understand what I intend to do. I used Matlab to make an animation. When making it, Camara orientation quaternion is not appropriate because of the integral error of angle velocity. Instead of that, I used image orientation quaternion. Image orientation quaternion has miller rotation, so the sign of three complex numbers, i, j ,k must be inverted. See
on 06-17-2021 05:34 AM
Sorry, below is correct.