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D435i auto focus function fails when UAV flies / D435i's video shaking and jittering (stuttering) when UAV flies

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6 comments

  • MartyG

    Hi Keystoradio  The RGB sensor of the D435i model is not suited to fast motion (motion faster than the waving of a human hand) as it has a slow 'rolling' type shutter, whilst its depth sensors have a fast 'rolling' shutter. 

     

    You can improve the performance of the D435i's RGB image by setting its FPS speed to 60, but this would mean reducing the RGB resolution to 848x480 as the maximum supported FPS for 1280x720 is 30.

     

    If you have the option to change the RealSense camera model in future then the D45x class of camera (D455, D455f, D456, D457) have a fast global shutter on both the RGB and depth sensors.

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  • Keystoradio

    Dear Marty:

    Thank you very much for your help. ^^

    However, the UAV does not move around and just hovers at a height. 
    On the other hand,  Amcrest USB Camera AWC201-B ($30 webcam, rolling shutter) also operates at 30 Hz, but there is no video shaking and jittering. 

    Therefore, I think  whether D435i has any auto focus function, which I forget to enable? 
    No matter what, I will try your advice (increase FPS to 60 and reduce the resolution to 848x480) and upload the video for further discussion.

    Thank you very much for your reply again : )

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  • MartyG

    D435i does not have auto-focus.  RealSense cameras have a fixed focal length.  They do have auto-exposure to adjust automatically to changes in lighting (for example, during the various phases of the day).

     

    You could check whether vibration is being transmitted through the UAV's frame to the RealSense camera.  The depth sensing algorithm is robust against vibration, though the RGB image may be more vulnerable to it.  If there is vibration of the camera then inserting a vibration damping pad on the camera's mounting point would help to reduce how much it is vibrated.

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  • Keystoradio

    Thank you very much.

    I also notice that the lightness also affects the blurring of D435i.
    There are D435i footages when UAV hovers. 
    Daytime (17:30 pm) and Daytime (17:40 pm) have stuttering. 
    Dusk time (19:00 pm) have blurring and stuttering.

    Daytime stuttering1 (1280x720, 30hz)

    Daytime stuttering 2 (1280x720, 30hz)

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  • Keystoradio

    Further use same mounting pads and test.
    Here is the results for two cameras.
    The left side is D435i when UAV hovers (Resolution 848x480) (60hz)
    The right side is Amcrest USB Camera AWC201-B  when UAV hovers (Resolution 1280x720) (30hz)


    The full size pictures of D435i when UAV hovers (Resolution 848x480) (60hz)

    The full size pictures of Amcrest USB Camera AWC201-B  when UAV hovers (Resolution 1280x720) (30hz)

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  • MartyG

    Thanks very much for the videos.  I have not seen that kind of 'wavy' disturbance on an RGB image before.

     

    The videos on the ground of the grass blades blowing showed that the air disturbance produced by the UAV must be significant.  I wonder whether the rippling could be disturbed air being captured by the RealSense camera's RGB sensor.  Is there another location on the UAV more protected from airflow that the camera could be mounted to test this theory?

     

     

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