Research On3D Fine Imaging Technology Based On Imaging Lidar And Dual-CCD Composite Imaging

Imaging lidar and dual-CCD stereo vision are two different three-dimensionalmeasurement techniques, they have their owen traits, lidar measurement has the featureof high distance precision and low spatial resolution, dual-CCD stereo visionmeasurement has the feature of high spatial resolution and distance precision of whichmay be affected by texture, light, and the distance factors. According to the features ofthe two measurement techniques, the paper introduce a fine three-dimensional imagingtechnology which can fuse these two techniques, by matching and fusing of thethree-dimensional images measured by two kinds of technique, the technology can getfine three-dimensional image with spatial resolution of CCD and distance precision oflidar. The paper mainly contains the following:Firstly, the related theories and key technologies of the fine three-dimensionalimaging technology based on lidar and binocular stereo vision are researched; thecomposite system implementation of imaging lidar and dual-CCD stereo vision ispresented. The paper researchs on the model and basic principles of dual-CCD stereovision, analyses the accuracy affected factors the of dual-CCD three-dimensionalmeasurements. According to the field of view constraints and the accuracy constraintsof imaging lidar and dual-CCD, the optimal structural parameters of the compositesystem are designed and an experimental integration system of imaging lidar anddual-CCD is established, which lays the foundation for composite finethree-dimensional imaging theory and experimental verification.Secongly, the camera calibration algorithm and two camera’s coordinate systemcalibration algorithm are researched. By analysing the existing camera calibrationalgorithm and introducing the lens tangential distortion, a more completed distortionmodel is established and the planar pattern calibration method is improved; further more,a dual-CCD coordinate system calibration algorithm based on planar pattern isresearched.Thirdly, based on the features of calibration of3D imaging lidar coordinate systemand camera coordinate system, a rotation and translation parameters separated methodfor solving transformation matrix is proposed, by using this method, the transformationmatrix can be solved only through changing the planar calibration target position threetimes. And then, the paper designes a three-dimensional calibration target which ismade up of three flat planes for solving transformation matrix, by using principalcomponent analysis on the plane of the three-dimensional target, the plane fitting errorcan be reduced. This method only needs one three-dimensional target position tocomplete the calibration of the lidar and the camera coordinate system, and has thefeatures of high precision and fast speed. Fourthly, the dense stereo matching method based on dynamic programming andthe method of merging lidar depth information into the image matching are researched.Base on the research, the paper proposes a pivoting method to fusing lidar data andCCD camera data, which use lidar disparity information as pivots to guide dense stereomatching. This pivoting method can improve the speed and accuracy of stereo matchingand can effectively deal with the textureless regions and occluded regions which areproblems in stereo matching. The simulation results show that the false match rate ofthis fusion method is lower than the lidar data and dynamic programming methodrespectively. In the real scene experiments, the results show that this method can detectoccluded regions in the image effectively, and in the region of lidar priori disparity canbe provided, this method can get a better disparity result regardless of the region istextured or textureless.Finally, through the comparison of a variety of reconstruction methods, the paperdecides using the minimum re-projection error method in unrectified binocular stereovision system and using the triangulation method in rectified binocular stereo visionsystem. By measuring the typical scene using composite system of imaging lidar anddual-CCD, a fine three-dimensional reconstruction result is got, and the effectiveness offine imaging technology is verified.