The three dimensional design theory of the grooved drum trench curved surface includes: 1)the indirect and direct design of the bottom datum curve;

槽筒沟槽曲面三维设计理论包括：1）槽底基准曲线的间接设计与直接设计；

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Should regard initial data in the charts of route location and curve elements as datum that coordinates calculate will just get the datum of high accuracy, Guide constructing accurately.

应以路线固定表和曲线要素表中的原始数据为基准推算坐标才会得到更高精度的数据，精确指导施工。

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Analyzing the experimental datum by regression, it draws the different influences of the modification of the weights of two kinds of control points on length of NURBS curve.

将实验数据回归分析，在此基础上得出两类控制顶点权因子的改变对NURBS曲线长度不同的影响结果。

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