How to calculate fisheye intrinsics?

I have performed camera calibration for a 360 camera and obtained camera params as follows:

However, I want the intrinsics to be in this form as it is the standard form used by many applications for image correction

How to format the parameters in the form shown above?

Answer 1

[Qu Cao]

You can use undistortFisheyeImage function to produce a "virtual perspective" camera intrinsics, which is the format you need. See syntax which returns "camIntrinsics". Note that in CVT, the intrisnics matrix is the transpose of the one you mentioned.

[Swapnil Sayan Saha]

Umm I do not want to undistort the image, I want the intrinsics to be of the form (or transpose of the form) I showed above. But if you see MATLAB output, the intrinsics is entirely something else, consisting of mapping coefficients and distortion centers.

[Qu Cao]

I understand that you don't want to undistor the image, but what I'm trying to say is that you can use the function as a workaround to get the intrinsics format you showed above. You only need the second output of this function. Note that the input intrinsics is a fisheyeIntrinsics object (what you have right now) while the output camIntrinsics is a cameraIntrinsics object (what you are asking for).

[J,camIntrinsics] = undistortFisheyeImage(I,intrinsics)

[Swapnil Sayan Saha]

Oh all right. Thanks a lot!