Camera overlay curved inwards

[Newtothissort (john)]

hey guys,

Ive spent almost 5 hours trying to calibrate my lens, i keep getting the same problem, the edge is curved inwards on the left and right. please ignore the bed not being fitted properly i just made it a bit smaller to see.

Using a generic USB camera

thanks again

[Newtothissort (john)]

here is another example, its bowed inward

[berainlb (PY)]

Did you go through the camera calibration process? If so, what kind of scores were you getting? Did you choose normal or fisheye lens?

How did you prepare the calibration pattern? Did you paste it to a known flat surface? Any slight distortion or bend in the calibration pattern will impact the quality of the distortion correction.

[Newtothissort (john)]

Hi,

i tried both flat and fish eye, i stuck it on a piece of acrylic and i also put a piece of glass on top.
i was getting a score between 0.1 and 0.6 i did all corners,i printed the dots on A4 and a A5.

I tried many different heights, they all come out the same. i have notice that my webcam is in reverse. but i put the camera upside down facing the laser its the correct orientation, as weird as that sounds, dont know if that plays a role

[berainlb (PY)]

@Newtothissort

i tried both flat and fish eye

You would only use the standard lens setting if your camera has no distortion out of the box. If there’s any distortion at all then use the fisheye setting.

@Newtothissort

and i also put a piece of glass on top

Have you tried it without the glass on top? I’m not sure how this might affect the calibration process.

@Newtothissort

score between 0.1 and 0.6

While adequate it would be better to get scores closer to .1 than .6. Even with .6 though I wouldn’t think you’d get the amount of distortion you’re seeing. Were you very careful to follow the instructions exactly? They are a little peculiar.

@Newtothissort

I tried many different heights

Height is relevant for alignment but should not be a major factor for calibration.

@Newtothissort

i have notice that my webcam is in reverse. but i put the camera upside down facing the laser its the correct orientation, as weird as that sounds

Is this reversed image in the live feed or just in the overlay? I don’t think this would affect the calibration but still a little odd. The alignment process can correct for camera orientation in the overlay but would not change the live feed.

[Newtothissort (john)]

yes i have tried it without the piece of glass, i have tried photo finish print on glossy paper too.
i collaborating with camera is sitting on table but the damn camera is mirrored its hard.
unfortunately i can only get 0.1 in the middle and it goes ranges to 0.2 - 0.6 everywhere else.