Research On The Generation Method Of High Quality Triangle Meshes Based On The Industrial CT Slicing Data

In the field of Reverse Engineering, because of its advantages of non-contactmeasurement，industrial computed tomography (CT) technology is widely applied tonondestructive testing for the products of complex inner cavity. However, restricted bythe scanning conditions and the influence of scanning environment, the data of scanningslice often has some defects, such as not getting the slice information of the workpieceabout its beginning and the end due to technical limitations, noise existing in thescanning process and so on. These data are used for the reverse rebuilt of the model, sothe reconstructing model has its drawbacks inevitably, mainly including the unclosedend of the model, the concave and convex on the surface of the model.To counter the existing problems of the reconstructing model, this paper takes thetriangular mesh model reconstructed by the data of industrial CT slices as researchobject, focusing on the unclosed end of the model, holes and defects, sags and crestsexiting on the surface of model.①End face repairing. To solve the problem of the unclosed end of the model,depending on the scanning interval difference of the model, this paper presents twodifferent methods of making the model end closed. For artifacts of small scanninginterval, the model end can be closed through the modification of MC algorithm, thatis,adding two blank section before reconstruction to ensure that the contour surface canbe extracted during reconstruction; for artifacts of large scanning interval, this papersuggests that to discriminate the internal and external contours of end face is the firstthing, then handling the internal and external contours of the face with triangularsubdivision, at last subdividing and fairing the section of the end face, finally achievingthe close of end face contour.②Hole repairing. Due to the artifact itself or the problems existing in thereconstruction algorithm, which leads to generating holes on the the surface ofreconstructing model, this paper propose to pretreat the boundary of the holes first. Andthen these holes will be triangulated by the improved advancing front mesh method. Atlast these holes will be disposed by smoothing method based on vector which isadjusted in the law of triangles, eventually making collection features of the model ingood condition and the transition zone connect smoothly.③Model Smoothing.In order to reduce the impact of noise in the process of scanning and eliminate the bump on the surface of the model after reconstruction, thereis a need to smooth the model, thus satisfying the requirements of the subsequentprocessing.This paper will rest in another median filter method to the average filteringiterative algorithm and weighted average filtering algorithm combined with the gridvertex filtering processing, and then through the method of vertex tangent plane anddirection vector to adjust the location of the grid vertex at the same time.The methodcan effectively remove the noise in the process, and better maintain the characteristicsof the model.④System integration and application.Integrates the end surface repairing, smoothhole-filling method and mesh smoothing integration into the existing software systems,and successfully applied to the complex inner cavity in reverse design of the products.By CT scanning of slicing data of the artifact to reconstruct the grid model, and thenthrough the end repair, smooth hole-filling method and mesh smoothing integration,finally making reverse reconstruct and entity modeling, the methods presented in thispaper are verified to be feasible and practicable.