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I try to do multi camera calibration.

In my situation ultimately I want to obtain second camera's extrinsic parameters or it's projection matrix from first camera's parameters (intrinsic and extrinsic).

I fix two cameras in rig and their distance and angle are also fixed. So I think I can find out their relationship and with this relation I can obtain second camera's parameters from the first one.

In real situation I install two cameras(fixed in rig) on the robot and in that situation I can't obtain all parameters. (I can obtain first camera's extrinsic parameters). So in this situation I want to do second camera calibration from first camera and their relation.

In the present I found first and second camera's distortion, intrinsic parameters and current extrinsic parameters. Of course extrinsic parameters are different with real situation. and I set their relation like this.

R_rel = R_2 * inv(R_1) ,  t_rel = -R_rel * t_1 + t_2

and I did

norimg_2 = R_rel * norimg_1 + t_rel  (norimg_1 = inv(intinsic_1) * img_1, norimg_2 = inv(intrinsic_2) * img_2

However I can't get right answer. I want to know if this relationship is wrong or this way is wrong.

  • Of course, 

    wld = [0, 0, 1];
imgpoint_1 = K_n.' * extrin_1 * wld.';
imgpoint_1_ = imgpoint_1/imgpoint_1(3);
imgpoint_2 = K_f.' * extrin_2 * wld.';
imgpoint_2_ = imgpoint_2/imgpoint_2(3);

like this I can get right answer. However I can't get extrinsic parameters _2 in real situation so I'm very confused.

J. Chomel
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1 Answers1

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I advise you work using a dichotomic approach, like in the bisection approach.

Bisection approach

You must try different values for parameters _2 that you can't guess. Then little by little, you change the values inside a frame that reduces more and more. In the end you have calibration for camera 2 for camera 1.

This means you have a way to evaluate the inaccuracy of the result you get for given values of parameters _2 .

If you don't find what you're looking for on SO, then you should also try https://photo.stackexchange.com/

J. Chomel
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