What is the intrinsicMatrix for an iPhone X rear camera?

Question

I'm looking for the camera Calibration Matrix from an iPhone X (but I don't have one to use).

Hoping someone has done enough iOS with ARKit to help me out with this.

Many thanks in advance!

Answer 1

The Intrinsic Matrix 3x3 (a.k.a. K-matrix) transforms three-dimensional Camera Coordinates into two-dimensional Homogeneous Image Coordinates.

The main 5 parameters are the followings:

fx, fy

The focal length is the distance between the pinhole and the image plane. You may find it strange but focal length here is measured in pixels. In a true pinhole camera, both fx and fy properties have the same value. But in practice, fx and fy often differ.

x0, y0

The Principal Point Offset is the location of the Principal Point relative to the film's origin. Film's origin is located at the bottom-left of the film (0,0).

s

Axis skew s causes shear distortion in the projected image. There isn't any analogue to axis skew a true pinhole camera, but apparently some digitization processes can cause nonzero skew (s/fx).

P.S.

For additional info read this post and this post.