Research On Simplification And Hole-filling Of Triangular Mesh Model Based On Industrial CT Image Sequence

Reverse engineering,which means the reverse analysis and research on a target product to solve the processing structure,features and technical specifications,design elements of the product,so that we can efficiently detect the defects and then carry out second development of products.As the best method for reverse engineering,industrial CT technology could obtained the surface and internal structure data of products without destroy it,then reconstruct these slice sequences by special algorithm to obtain the structure of the target product,And then develop and design the error analysis and finite element analysis.Aiming at the problems existing in the 3D mesh model reconstructed by industrial CT slice sequence,the paper focuses on the research of mesh reconstruction,simplification and hole-filling,the main research contents and achievements are as follows:(1)In order to reconstruct the slice data of industrial CT to obtain more reliable 3D model,this paper first analyzes the commonly used methods of 3D mesh model reconstruction,and the Marching Cubes method is used to reconstruct the CT image sequence.The experimental results of several models show that the proposed algorithm can reconstruct the CT image to 3D model well.(2)Considering that some triangular mesh models reconstructed from CT image sequence are inconvenient for storage,analysis and display due to huge data volume,a new mesh simplification algorithm based on mesh refinement is proposed.First uses ?3 surface subdivision method to calculate corrected coordinates of three vertices of the collapsing triangle,and determine the position of folding point preliminary,then introduces the Laplacian coordinates and normal information of collapsed triangle to update the position of folding point,and the cost of all collapse operations were calculated according to the volume error and flatness of collapsed triangle,so that the mesh model is simplified from relatively flat region with less feature points by triangle collapse in turn.Through many experiments and data analyses of different models,the results show that the proposed method can effectively reduce the mesh data.Compared with three different types of simplification methods,this algorithm works highly efficiently and can effectively maintain the geometric characteristics of the original mesh model and control the quality of the simplified triangle to a certain extent.(3)Triangular mesh model generated from CT image regularly appear some holes.In this paper a novel hole-filling algorithm for space polygon is proposed.Firstly,we extract the holes boundaries and save information of boundary vertices,then control the growth of new triangles coordinately by calculating boundary flatness and vertex's projection angle of holes polygons;meanwhile,we lead in the vertex's directional curvature adjustment angle and adjustment factor of normal vector while inserting new points in order to achieve a smooth transition and high-quality triangles.Experimental results show that the algorithm is simple,effective and the holes meshes are capable to transit smoothly with original meshes.(4)The method and process of reverse design using industrial CT technology are introduced with an example.The scanned slice images are reconstructed,repaired and simplified by using the method of this paper to obtain the triangular mesh model.Then use the special software to render the model in reverse entity and compare it with the original point cloud model and analyze the error.The reverse design provides a reference for the absorption of advanced design methods.