Abstract
This paper describes the method of measuring a point on a three-dimensional space with a stereo camera using geometrical invariants. An affine invariant and a projected invariant are used as geometrical invariants. The measurement space is sandwiched by two planes which consist of eight points. The eight points are called reference points. The process of measurement is as follows. The geometrical invariant is calculated from the reference points on the images. The geo-invariant is applied to the reference point three-dimensional space, and the three-dimensional point is set on the two planes. The measurement point is calculated using the points set on the reference planes. The experiment is performed using affine invariants, projected invariants, and camera parameters which are calibrated as a stereo camera system. The conclusion of the experiment illustrates that by using projected invariants the same results as when using camera parameters can be found.
