Research On Fragment Matching Based On Contours In Reverse Engineering

For a long time,the restoration of artifacts debris often takes time and effort.In most cases,there are no original pictures of archeological fragments for reference.With the development of digital scanning equipment and visualization technology,the application of reverse engineering technology such as debris scanning,point cloud processing,data modeling and virtual splicing will provide great convenience for cultural relic repair.Therefore,to study how to use computer to assist cultural relic repair has important historical and practical significance.In this paper,the general shape of the three-dimensional fragments as the object,and based on the boundary point cloud matching,research to achieve more accurate fragments splicing recovery.The main contents of this paper are divided into the following aspects:First,the extraction of the boundary of the fragment is completed by the extraction algorithm of the boundary points based on the normal vector.The algorithm uses PCA algorithm to quickly estimate the normal vector of point cloud and determine the boundary point by the included angle of the normal phase.Aiming at the situation that the extracted boundary points are scattered and disorderly in the outline direction,a directed polyline algorithm is used to output the disorderly boundary points.Secondly,in the stage of boundary sequence matching,we propose a multi-scale matching strategy in this chapter,and divide the matching into two stages: rough matching and fine matching.In the rough matching stage,a larger sampling scale is used to sample the original boundary sequence.The sequence of features corresponding to the boundary sequence at this scale is solved,and the key points and sub-endpoints are screened out according to the characteristic conditions so as to provide data support for the fine matching phase.In the stage of fine matching,an MVM matching algorithm based on integral invariants is proposed.Integral invariants in this algorithm can guarantee the accuracy of feature points calculation and make use of the characteristics of MVM algorithm to achieve the correct matching between the starting point and the ending point.Through the comparison of the examples,the matching method proposed in this chapter has a good accuracy and a reasonable matching position,which can play an important guiding role in the correct matching and splicing of fragments.Finally,aiming at the problems after the patch splicing,by solving the optimization matrix of the patch at the crack line,the patch splicing is smoother.In addition,based on the existing point cloud processing system of this project group,the mosaic result of the fragments is demonstrated,which shows the feasibility and effectiveness of the algorithm and point cloud processing system studied in this paper.