Camera auto-calibration without calibration board?

Question

Algorithms

There is this algorithm for calibrating the camera simply from photographs, without a calibration board.
www.kaynig.de/downloads/DistortionCorrectionPlugin...
picture to attract attention
www.kaynig.de/images/workflowDiagram.PNG The
question is what is this algorithm.
as I understand it, SIFT is used for comparisons and something like an optical flow is considered, the parameter "power of polynominal kernel" apparently indicates that the distortion itself is set by a polynomial, but it is not clear where lambda is involved as a regularization parameter (it can be solved something like a system non-linear equations?).
I forgot to write that the fact is used that in the center of the image the distortion tends to zero, and at the edges, on the contrary, it takes on a maximum value.
UPDATE:
everything seems to be described in the paper: "Fully automatic stitching and distortion correction of transmission electron microscope images"