UNDERWATER VIDEO CAMERA CALIBRATION METHOD Russian patent published in 2023 - IPC G01C11/00 

FIELD: information and measurement systems.

SUBSTANCE: invention relates to information and measurement systems, in particular to computer vision system used under water for determining three-dimensional coordinates of specific points of objects observed by a video camera. Underwater video camera calibration method is based on the use of an underwater manipulator with a calibration object in its grip. The calibration object is brought to the initial point of the camera's working space by means of the manipulator's standard control system (SC). The calibration object coordinate in x1-axis is recorded in the first cell of the first two-dimensional memory matrix that corresponds to the first plane of the workspace. Then two other coordinates of the object - y1, z1 - are determined via video camera calibration object image on a photosensitive matrix observed by the camera taking the diagram into account, and the coordinates are successively stored by the second and the third number in the same cell of the two-dimensional memory matrix. After that, the fourth and fifth numbers, which are the differences between the corresponding coordinates of the calibration object obtained from the manipulator and the video camera in the camera coordinate system (CS), are determined and recorded in the same memory cell. The two-dimensional arrays of memory cells created for each plane are placed sequentially in the appropriate place in the generated three-dimensional memory matrix taking into account their distances from the camera image plane. The video camera calibration method procedure is repeated until the three-dimensional memory matrix, which contains the information about the real distortions of the observed images in the corresponding points of the video camera working space, is completely filled.

EFFECT: invention increases calibration accuracy via forming matching values of pixel coordinates of arbitrary points of working space monitored by a video camera and their real coordinates in the used coupled CS before a three-dimensional matrix camera starts operating.

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