Camera Calibration issues
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Hi modal AI support,
I am trying to calibrate my starling 2 drone camera using openCV 6x8 chessboard (I used this command " voxl-calibrate-camera tracking_front -f -s 6x8 -l 0.038". I think my camera lens might be dull, I have a starling 2 Lens Focus Tool, but I can't find any resource to help me adjust the focus. I have attached an image of me me trying to calibrate the camera so that you clearly understand what I am trying to say. From the first image, you can see how blurry the chessboard is, In the second image, you can see that the chessboard is barely showing when the chessboard was moved inside the rectangle. The third image are what I saw in the starling 2 Lens Focus Tool.
Kindly assist.
Thanks,
Taiwo
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@taiwohazeez , the image is indeed blurry. Did the camera come like this or did something happen to the camera / lens?
Also, i am assuming that the blur is not coming from the camera moving around (that is to say the camera is stationary during those image captures).
Please inspect the lens on the outside to make sure it's not scratched or damaged, as this can also contribute to the issue.
In any case, adjusting focus on a camera is usually as simple as turning the lens slightly CW or CCW. Since the image is almost focus, i expect that the adjustment would be within 1 full turn from the existing lens position in the lens holder. If the camera lens is being held by a plastic mount, it should have a screw on the side of the plastic mount, which clamps the mount around the lens. The screw needs to be loosened and then you can use the focus tool to turn the lens slightly while looking at the image view in
voxl-portal. For this particular camera with a wide lens, the hyperfocal distance will be around 10cm, meaning that when properly focused, everything beyond 10cm away should appear in focus. With this in mind, you should some target (checkerboard is fine) 0.3 - 0.5m away and turn the lens back and forth (with the plastic tool) to try achieve the best focus. If you cannot achieve good focus (the best focus is still blurry), it probably means that either the lens is damaged dirty (front or back side of the lens).If you do unscrew the lens all the way out (by turning counter-clockwise until the lens comes out), don't leave the camera exposed like this for a long period of time, so that dust does not get on the camera sensor.
Also, what is the exposure and gain reported in the stats below the image in the voxl-portal view, when you view the camera stream (without the calibration). The environment seems pretty dark, i would recommend more lighting, but let's double check the reported exposure and gain (from auto exposure). Also, please make sure your checkerboard pattern is as flat as possible (this is unrelated to blurry image, but will result in better calibration results).
Please try focusing the camera and let me know if you have any questions.
Alex
