Calibration

It has been proved that, according to the pinhole model, there is a 3x3 matrix, noted F, so that:

F depends only on the relative positions of the sensors and their intrinsic parameters. It is said that F codes the epipolar geometry of the sensors.

Relation (*) can be seen as follows: the point m₂ lies on the line defined by F.m₁; it lies on a line depending only on m₁ and the epipolar geometry. This line is called the epipolar line associated with m₁; the relation is then a weak version of the epipolar constraint.

To weakly calibrate a sensor system is to estimate F.

The weak calibration can be divided in two steps:

• the search for homologous pairs;
• the estimation of F which best verifies the relation (*) on these pairs.