DJI Osmo Action 4 Calibration and FFS

1

Hi,
I have an Action 4, What Frame rate should I record or does it not matter? I though higher would allow us to slow the game down but still have clear images.

Also I’ve used the Osmo 4k but its a bit hit or miss as to stitching, is there a new config that is needed.

Thanks

Kevin

2

Hello Kevin,

At this point I am also testing the DJI Action 4.
I record in 4k @48fps, FOW: standard (Dewarp)
I am also in trouble with the stitching process.

Used: GitHub - smidm/video2calibration: Camera intrinsic parameters calibration from chessboard video sequence. to do the calibration for Dewarp FOW, but no luck so far. For sure I am doing something wrong.

  • Output of Calibration process.
    RMS: 0.980197190807896
    camera matrix:
    [[761.92778301 0. 954.92891518]
    [ 0. 761.04279889 538.13629642]
    [ 0. 0. 1. ]]
    distortion coefficients: [-0.02771575 0.0449596 -0.00216196 -0.00121916 -0.02398366]

  • OsmoAction4_Normal_Mode.json
    {
    “distortion_coefficients”: [-0.02771575,0.0449596,-0.00216196,-0.00121916,-0.02398366,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0
    ],
    “intrinsic_matrix”: [761.92778301,0.0,954.92891518,0.0,761.04279889,538.13629642,0.0,0.0,1
    ]
    }

2025-08-12 234539
2025-08-12 2345391101×537 92.3 KB

3

I have design a case to hold 2x DJI Action4.
I will share 3d step files when prototyping is done.

afbeelding
afbeelding623×876 76.8 KB

4

Some of those new action cameras may be hard to calibrated using the standard opencv camera model. The fisheye model may work better. @Rufan can you send me the calibration video as well as sample videos for left and right so I can test the calibration results?

5

You’ll need to retake the calibration video at 4K rather than 1080p. Make sure it should use the same dewarp and stabilization settings as the sample videos, but ideally when you shoot game videos both dewarp and stabilization should be turned off.

Also, show the checkerboard on the large monitor or TV. Printed checkerboards on paper are usually warped which may affect the calibration.

6

@gchen.

I checked back the calibration I did it was 4k48fps, sorry uploaded the cropped version.
FOV: Standard (Dewarp), stabilization if OFF.

I will make a new video with checkboard on TV.
I really like to shoot the game in Standard (Dewarp) to get rid of the curved horizon.

7

When Dewarp is on, you’ll still get the curved horizon with the stitched panorama.

The reason we should avoid Dewarp is that it crops out a portion of pixels around the edge, reducing the overlap which makes it hard to find feature points within the overlap.