Study On Large-scale 3-D Detection Technology Of Underwater Structured Light

In order to realize the high-precision and large-scale measurement of the underwater object, an underwater structured light large-scale 3-D detection system based on line structured light that is mainly composed of CCD cameras, a line structured light generator and a vibrating mirror is proposed, based on the theory of image processing and machine vision. First, a detection system is designed and by analyzing the principle of the system, a model of the system is established. Second, the main parameters that influence the accuracy of the system are analyzed and the calibration method is presented. Finally, the underwater target 3-D data is obtained by the use of compensation algorithm, the system and the calibration method proves to possess comparatively high precision by the experimental measurement result. The main work in the dissertation can be summarized as follows:1. A calibration method of system parameters is presented. In this detection system, the accuracy of the system is to a large extent influenced by the rotation matrix and the translation vector between the two coordinate systems. The focal length is calibrated by the use of calibration method based on range arrangement constrain, based on this method and the position relation of optic center, camera's image surface and calibration target, light plane equations can be obtained. The rotation matrix and the translation vector between the two coordinate systems are achieved by the relation of light planes and the coordinate axis rotation.2. The Acquisition of underwater object's 3-D data. When the underwater measurement is chosen, the vibrating mirror can be rotated automatically, first light plane equation needs to be corrected and the camera's image surface coordinate needs to be compensated, then the underwater object's 3-D data are obtained by the using the pinhole imaging model and the light plane equation.3. An underwater structured light large-scale 3-D detection system and the control software of the system is designed. According to the rotation of the vibrating mirror and the light planes the object's 3-D data can be obtained quickly. Special control software is developed and the dynamic link library of structured light control for AUV is completed. All of the calibration and detection works can be achieved.The innovations of this dissertation are proposing a new calibration method which can obtain the rotation matrix and the translation vector between the camera coordinate system and vibrating mirror coordinate system. The underwater structured light large-scale 3-D detection system is accomplished; object's 3-D data can be obtained and the navigation of AUV can be achieved by using of the system.