Research On 3D Scanning Technology For Cultural Relics

In order to quickly acquire the data of cultural relics,the thesis studies the threedimensional scanning technology of small cultural relics,proposes a complete threedimensional scanning scheme of cultural relics,and constructs a complete three-dimensional scanning system.In the thesis,the calibration of the rotating axis uses the checkerboard target to tilt the self-made two-dimensional checkerboard target by 25 angle on the high-precision rotating platform connected by the stepper motor controller.The stepping motor controls the rotating platform to rotate 360 angle,and images are taken at multiple angles.A clear image is obtained by processing the captured image to obtain the spatial coordinates of the feature points on the target.The spatial feature is used to obtain the set of spatial center coordinates,and then the spatial straight line fitting method is adopted.After the obtained sets of center coordinates are processed,the fitted straight line equation is obtained.According to the distance between the set of center coordinates and the straight line equation,the deviation points are eliminated,and the multiple sets of centers after the deviation points are again subjected to spatial straight line fitting,and finally fitted.The linear equation of the rotating axis of the rotating platform,that is,the calibration of the rotating axis is completed,the accurate three-dimensional point cloud data is obtained by the rotation scanning,and the registration of the point cloud of the cultural relic surface is completed according to the rotation matrix between the point clouds.For this reason,this thesis mainly completes the following two aspects:(1)The calibration of the rotating shaft of the rotating platform is realized.According to the relationship between the internal and external parameters obtained by the camera calibration,when the rotation platform is rotated at different angles,the three-dimensional coordinates of the corners of the checkerboard on the rotating platform in the camera coordinate system are accurate to the sub-pixel level.The spatial circle fitting method is used in the rotating platform different rotation Angle in each corner of the three-dimensional coordinate for processing,then the more groups of space center coordinates,then the space straight line fitting method is adopted to the center group after treatment was more fitting straight line equation is obtained,then according to the center of the circle,the distance to the fitting line to eliminate deviation points,to eliminate the deviation point again after multiple sets of linear fitting,center for space can be fitting the linear equation of rotation of the rotating platform.(2)Three-dimensional scanning for cultural relics is realized.By rotating scanning,the three-dimensional point cloud data of the cultural relics to be tested are obtained.The rotating axis parameters and rotating angle obtained after calibration of the rotating platform are used to realize point cloud registration,and the scanning results are evaluated.The thesis completed the research of three-dimensional scanning technology suitable for small cultural relics.The calibration result of the camera was evaluated by the re-projection method.The average error calculated by the re-projection was 0.254732 pixels,the coincidence degree was 65%~75%,and the calibration process of the rotating axis was completed.The average variance of the space-space fitting result is 0.0349,and the variance of the spatial straight-line fitting result is 0.0276,and the point cloud registration of the acquired point cloud data is performed by the calibrated rotation axis parameter and the rotation angle,has certain advantages.