Wide angle lenses calibration with Opencv

Question

I\'m using a wide-angle lens (178º Diagonal FOV ) and I\'m trying to calibrate it properly using Opencv Calibration module. All the detection and calibration process are working

Answer 1

Maybe the camera/lens model of OpenCV does not describe accurately enough your ultra wide angle lens. And so maybe you have to abandon the built-in OpenCV calibration procedure and write your own calibration procedure.

For example a google search gives me:

Kanatani, K., "Calibration of Ultrawide Fisheye Lens Cameras by Eigenvalue Minimization," Pattern Analysis and Machine Intelligence, IEEE Transactions on , vol.35, no.4, pp.813,822, April 2013

Abstract: We present a new technique for calibrating ultrawide fisheye lens cameras by imposing the constraint that collinear points be rectified to be collinear, parallel lines to be parallel, and orthogonal lines to be orthogonal. Exploiting the fact that line fitting reduces to an eigenvalue problem in 3D, we do a rigorous perturbation analysis to obtain a practical calibration procedure. Doing experiments, we point out that spurious solutions exist if collinearity and parallelism alone are imposed. Our technique has many desirable properties. For example, no metric information is required about the reference pattern or the camera position, and separate stripe patterns can be displayed on a video screen to generate a virtual grid, eliminating the grid point extraction processing.