Camera sensor

Robotics / sensors

focal length $ f_{x}, f_{y}$

Focal length is the distance from the lens’s optical center (or principal point) to the image sensor when the subject is in focus. in true pinhole camera \(f_{x} = f_{y}\)

$ f_{x} = \frac{\frac{W}{2}}{tan(\frac{hfov}{2})} $

$ f_{y} = \frac{\frac{H}{2}}{tan(\frac{vfov}{2})} $

Principal Point $ c_{x}, c_{y}$

pixel location where the optical axis hits the sensor. Often close to the image center, but not necessarily exactly , \(\frac{W}{2}, \frac{H}{2}\)

Intrinsic

Camera internal parameters

Minimal

$ k=\begin{bmatrix} f & 0 & c_{x} \ 0 & f & c_{y} \ 0 & 0 & 1 \ \end{bmatrix} $

General

$ k=\begin{bmatrix} f_{x} & s & c_{x} \ 0 & f_{y} & c_{y} \ 0 & 0 & 1 \ \end{bmatrix} $

FOV (Field Of View)

The angular extent of the scene captured by the lens