Method for calibrating the initial position and the orientation of one or several mobile cameras

A method for calibrating the original position and orientation of a first camera disposed on a mobile support in an environment with respect to a second camera, the cameras being disposed on independent supports mobile in the environment, the method comprising:

• providing the first camera with a calibration camera and the second camera with a test object at a known position and orientation;
• taking an image of the test object with the calibration camera;
• analyzing the image of the test object with a processing system by reading position of tracks (Pp) of characteristic marks of the test object on the image;
• deducing directions and distances between the characteristic marks and the calibration camera, then a position and an orientation of the calibration camera with respect to the test object, and then of the first camera with respect to the second camera, wherein the directions and distances between the characteristic marks and the calibration camera are deduced by carrying out a retro-projection of the centers of the tracks of the characteristic marks of the test object first on to a plane (II) passing through the origin of the test object reference frame and parallel to the plane of the image along lines converging towards a single focus (F), then in space, perpendicular to the said parallel plane in order to obtain retro-projection points (° P), and then, iteratively, a projection of the retro-projection points (° P) on to the plane of the image along lines converging towards the focus (F) in order to obtain projection points (° Pp) , and a positional correction of the retro-projection points in order to minimize an error estimation criterion between coordinates of the centers of the tracks (Pp) of the characteristic marks and die projection points (° Pp).

A method for calibrating the original position and orientation of a first camera disposed on a mobile support in an environment with respect to a second camera, the cameras being disposed on independent supports mobile in the environment, the method comprising:

• providing the first camera with a calibration camera and the second camera with a test object at a known position and orientation;
• taking an image of the test object with the calibration camera;
• analyzing the image of the test object with a processing system by reading position of tracks (Pp) of characteristic marks of the test object on the image;
• deducing directions and distances between the characteristic marks and the calibration camera, then a position and an orientation of the calibration camera with respect to the test object, and then of the first camera with respect to the second camera, wherein the test object comprises at least three marks in the field of the camera to be calibrated,
• wherein the directions and distances between the characteristics marks and the calibration camera are deduced by carrying out a retro-projection of the centers of the tracks of the characteristic marks of the test object first on to a plane (II) passing through the origin of the test object reference frame and parallel to the plane of the image along lines converging towards a single focus (F), then in space, perpendicular to the said parallel plane in order to obtain retro-projection points (° P), and then, iteratively, a projection of the retro-projection points (° P) on to the plane of the image along lines converging towards the focus (F) in order to obtain projection points (° Pp) , and a positional correction of the retro-projection points in order to minimize an error estimation criterion between coordinates of the centers of the tracks (Pp) of the characteristic marks and The projection points (° Pp).

A method for calibrating the original position and orientation of a first camera disposed on a mobile support in an environment with respect to a second camera, the cameras being disposed on independent supports mobile in the environment, the method comprising:

• providing the first camera with a calibration camera and the second camera with a test object at a known position and orientation;
• taking an image of the test object with the calibration camera;
• analyzing the image of the test object with a processing system by reading position of tracks (Pp) of characteristic marks of the test object on the image;
• deducing directions and distances between the characteristic marks and the calibration camera, then a position and an orientation of the calibration camera with respect to the test object, and then of the first camera with respect to the second camera,
• wherein the position and the orientation of the calibration camera with respect to the test object are deduced in the form of a position (t) and an orientation (R) of the camera to be calibrated with respect to a reference frame related to the test object,
• wherein the directions and distances between the characteristic marks and the calibration camera are deduced by carrying out a retro-projection of the centers of the tracks of the characteristic marks of the test object first on to a plane (II) passing through the original of the test object reference frame and parallel to the plane of the image along lines converging towards a single focus (F), then in space, perpendicular to the said parallel plane in order to obtain retro-projection points (° P), and then, iteratively, a projection of the retro-projection points (° P) on to the plane of the image along lines converging towards the focus (F) in order to obtain projection points (° Pp) , and a positional correction of the retro-projection points in order to minimize an error estimation criterion between coordinates of the centers of the tracks (Pp) of the characteristic marks and the projection points (° Pp).