Rebuilded And Modified Surface Model Based On Cross-section Curves For Points Cloud On Reverse Engineering

As an important component of advanced manufacturing technology, reverse engineering gradually developed into an important technical means of product innovation and new product development from the initial prototype support replication technology. It was widely used in automobile, aircraft, household appliances and mold manufacturing, and produced a lot of relevant equipments and software. However, when it comes to a comprehensive systematic solution to the reverse engineering CAD model about complex physical parts, there are still many problems remain to be resolved.In the context of reverse engineering technology for feature modeling, this paper focuses on the understanding of the product design intention and the measured points cloud, takes rebuild surface model supporting for product innovation as the goal, and studies the key technologies in reverse engineering CAD modeling, such as points cloud data preprocessing, curve fitting and optimization of cross sections, surface reconstruction and modification and so on. Specifically include the following aspects:(1) In the pre-processing of points cloud data. Use hypotenuse-height method to remove noise points in the points cloud data; angle and hypotenuse-height method to simplify the points cloud data; the average of the data to smooth the points cloud.(2) In the part of section curve fitting. The thesis researches on the segmentation algorithm based on point cloud data for section, the least-squares fitting algorithm of line, arc and B-spline, and proposes feature recognition technology which is based on the average error of the curve fitting.(3) Based on the identification of cross-section curves and the curve fitting, we build the constrained optimization model for the whole cross-section curve after recognized and analysed the constraint between segmented curves. We take cross section composite curve by work out the model.(4) Fitting a number of cross-section points cloud data to obtain cross-section composite curve group. According to surface continuity, We establish the relationship between feature points of cross-section composite curve. Use skin method to generate surface. To the rebuilt surface, local research have been done in the part of equidistant offset surface and surface modification.