Procedure to calibrate a camera based on an image in which a circle and at least one line are visible

摘要

Method for calibrating a camera (10) based on an image in which a circle (1) and at least one line are visible, comprising the steps of: a. Calculation of a homography (H) that transforms the circular unit into the circle (2) projected in the image; b. Complete determination of the homography (H) that transforms the reference plane (3) in the scene (real world) in the projected plane (4) on the camera (10) on the basis of two additional geometric elements; and c. Calculation based on the homography (H) of the focal distance (f) and the position and orientation of the camera (10) in space, characterized in that said homography (H) that transforms the reference plane (3) into the scene in the projected plane (4) on the camera (10) is: ** Formula ** where: ** Formula ** and α, ß are already parameters (α and ß are angles is already a distance), calculated on the basis of the information provided by said two additional geometric elements mentioned that are the point of the center (7) of the circle (1) and a straight line (5) that crosses the center (7) of the circle (1); being the distance a and the angle α obtained from the following relation ** Formula ** where (0,0) is the center of the unit of circle y (x0, y0) is its projection (8) on the image in the camera ( 10); and the parameter ß is obtained from the relation ** Formula ** where is said straight line (5) that satisfies the condition and "s" is an arbitrary scale factor.