extracting .braw gyro data and understanding how to use it

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KokoSvech

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  • Joined: Mon Feb 13, 2023 11:07 am
  • Real Name: Konstantin Svech

extracting .braw gyro data and understanding how to use it

PostMon Feb 13, 2023 11:19 am

Hi there,

I'm coding a .braw importer for Blender3D.

For now I just want to map the gyro data to a camera inside of blender.
I've successfully extracted the data from the .braw file using the BM Raw SDK.
Now I'm struggling with understanding the data structure.
Is there some more specific specs and/or references on the Gyro and Acceleration data extracted from a .braw file.
How is the Gyro and Acceleration Data organized?

Can someone help me with this?

Many thanks and greets from Germany!

Konstantin
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CaptainHook

Blackmagic Design

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  • Location: Melbourne, Australia
  • Real Name: Hook

Re: extracting .braw gyro data and understanding how to use

PostMon Feb 13, 2023 9:04 pm

Hi,

Briefly the data is stored as:

Gyro = Radians / Second
Accelerometer = metres per second squared (m/s/s or m/(s^2))

The other useful information when it comes to stabilisation is sensor_line_time = micro seconds (us). This is the time a single line takes to be read and can be used to calculate overall read out speed to try compensate for rolling shutter etc. Eg For Pocket 6K depending on record format you might get something like ~5.708us for sensor line time - assuming 3456 pixels high this would mean 3456 pixels *~ 0.005708 = ~19.73ms as a read out speed for the frame.

Gyroflow is open source and using Blackmagic RAW gyro data in their app so you may want to check their source for inspiration/ideas if needed:

https://github.com/gyroflow/gyroflow
**Any post by me prior to Aug 2014 was before i started working for Blackmagic**
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SteveDGreen

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Re: extracting .braw gyro data and understanding how to use

PostSun Feb 26, 2023 1:28 pm

Getting the gyro data into a 3D app's camera would be interesting

I've mentioned elsewhere that it would seem to be quite useful for sky/background replacement on a moving camera (or anything where the lack of xyz position data doesn't really matter)

I even wondered if it's the sort of thing the new studio cameras could do something with live (since they're tripod mounted) for virtual sets, without any external trackers

Cheers,

Steve
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WilliamDio

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  • Location: Montreal
  • Real Name: Guillaume Boivin

Re: extracting .braw gyro data and understanding how to use

PostFri Jun 16, 2023 5:41 pm

That's amazing! I was starting to think along those lines (mostly for matching camera movements on 3D elements for green screen backgrounds. Please let us know about the progress and if we can help (I'm afraid I'm not much of a coder, but I'd be willing to be a beta tester on this).

Thanks!
Will
In science, failure is a valid result.

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