Partition local fairing weight factor-based T-spline curved-surface fitting method

Abstract

The present invention discloses a partition local fairing weight factor-based T-spline curved-surface fitting method. The method comprises the following steps of inputting a parameterized triangular grid and an initial T-spline; segmenting the region of a parameter domain to obtain a plurality of sub-regions of the parameter domain; according to the topological structure of the original image of the control grid of the input T-spline on the parameter domain, generating a fairness inspection point set; according to the density weight of each fairness inspection point and the local fairness weight factor of the sub-region of the above fairness inspection point, calculating the local fairness weight of each fairness inspection point; according to the fitting error of each vertex of the triangular grid and a curved-surface fairness energy column equation set, conducting the least square solution method to obtain a final T-spline curved-surface fitting result. According to the invention, fairness inspection points are adaptively generated according to the complexity of a control grid. Meanwhile, the fairness and the accuracy of different regions are coordinated through partition and local fairness weights. Therefore, the quality of a fitting surface is improved and the calculation efficiency is increased.

Description

technical field [0001] The invention relates to the field of spline surface fitting methods, in particular to a T-spline surface fitting method based on partition local fairing weight factors. Background technique [0002] Spline surface technology is one of the core technologies in the CAD / CAM field, which describes the geometric shape of the model in the form of polynomial parametric surfaces. T-spline technology is an advanced spline surface modeling technology proposed in recent years. It is suitable for expressing complex geometric shapes with a single surface, so it has received extensive attention from the academic community. T-spline surface modeling technology is one of the cores of T-spline technology research, and T-spline surface fitting technology is the most basic link. Improving the efficiency and effect of surface fitting method is the key to improving spline surface modeling technology. One of the keys. [0003] The T-spline surface fitting method usually ...

AI Technical Summary

Problems solved by technology

Although this method can adjust the weight of fairing and precision in the fitting calculation through the global fairing weight, in some cases, some areas of a surface may have low accuracy, while other areas are smooth poor sex situation

At this time, it is difficult for this method to meet the needs of different regions at the same time

On the other hand, in order to ensure the reliability of the results, the method of evenly arranging the fairness checkpoints needs to add a large number of smoothness checkpoints, which brings an additional burden to the calculation

[0004] The T-spline surface fitting methods proposed so far all set the smoothing energy weight in the form of global smoothing weight, and do not treat different regions differently, so the smoothness of the surface cannot be locally adjusted

In addition, the smoothness inspection points in the existing method are evenly distributed, and the differences of T grids in different regions are not fully considered, which affects the calculation efficiency

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