二维二次曲面

Firstly part of quadratic term of Taylor series is chosen; a low-dimension surface is used to approximate limit state surface ; and the modified reliability formula is derived.

首次选取泰勒级数的部分二次项，用一个距原点最近点处拟合的超低维曲面近似极限状态面。

On the basis of OCM, segmentation based on curvature radium is presented in the paper, in which curvature radium is calculated using parametric-surface fitting, and detecting edge points is realized from orthogonal direction, which ensure the integrality of edge points. Since the data is organized by cross-line in OCM, a new arithmetic, Double-direction Angle Difference arithmetic, is brought forward, which can pick up edge points more quickly.

物体的表面一般由多个曲面相交组成，要建立完整的几何模型，需要对测量数据进行区域分割——区分不同曲面的数据，现有的区域分割大多是对单视图的图像式测量数据进行的，但完整的CAD模型需要联合多个视图产生，本文在上面提出的三维正交模型的基础上，提出了三种区域分割方法：第一种方法是基于曲率半径的数据分区方法，通过二次参数曲面拟合计算局部曲率半径，从正交的多个方向进行检测，保证了边点提取的完整性。

This paper proposes a robust filter function, called trilateral filter function, to filter the noises in the domains of surface curvature, normal and position at each sample point while the local surface is fitted in a quadratic form. By optimizing the filtering result of curvature tensor, our approach is capable of preserving the feature on the target model.

通过在扫描模型每个采样点处拟合一个二次型曲面，设计了一个鲁棒的滤波函数--三边滤波函数；应用该函数分别对模型表面上每个点的法线、曲率和位置进行滤波；通过对曲率的滤波结果进行优化，可有效地保持三维模型表面上的特征。

The principle of the fractal-interpolated surface was discussed. The formula and the theorem of fractal dimension of the fractal-interpolated surface were analyzed. The numerical analysis of height anomaly fit by the fractal interpolated surface and the result comparison with the quadric polynomial surface model with practical data were given.

本文论述了分形插值曲面的原理，分析了分形插值曲面的计算公式，讨论了分形插值曲面的维数估计方法和公式，用实际数据进行了分形插值曲面拟合高程异常的数值分析以及与二次多项式曲面拟合模型结果的比较。

It is proved that two images of the quadric surface is not enough to reconstruct the quadric surface.

我们证明了两幅视图轮廓包含的信息不足以重构二次曲面，三幅视图对于恢复二次曲面三维表面是充分而巨必要的。

Classifying and computing a QSIC (quadric surface intersection curve) are important operations in computing the boundary representation of a solid in solid modeling system, and also are applied in other geometric processing.

对两二次曲面交线(QSIC-Quadric SurfaceIntersection Curve)的拓扑分类和计算是立体造型系统计算三维物体边界表示的一个非常重要的操作，同时还可应用在其它的几何处理算法中。

Some questions in digital elevation model were discussed detailedly, such as the obtaining of data points, the fast searching of reference points, the interpolation algorithm of quadric surface, the abnormal data eliminating, and so on. And this paper has realized the 3D vectorization of 2D terrain maps, the 3D display and edit of DEM data with the help of secondary development of CAD.

文中详细讨论了数字高程模型中数据点获得、参考点的快速搜索、二次曲面的插值算法、粗差剔除等内容，并运用AutoCAD二次开发技术，实现了二维地形图的三维矢量化以及DEM数据的三维显示和编辑修改。

Based on data cloud, which is measured from 3-coordinate measuring machine or so, an algorithm to search lopological structure from 3D unorganized points using Envelopment-box technology is proposed in this thesis. Based on this method, we searching neighbor points of sampling point. We also improve the Max-Min angle criteria to realize local triangulation, and then get the normal of sampling point from the triangulation. Using the normal and neighbor relationship, classification of scattered data points is realized according to the quadric surface.

本文以测量得到的曲面数据点点云为基础，提出了一种基于包围盒的自动寻找三维散乱数据点之间拓扑结构的方法，采用该方法寻找采样点的邻域结点，并对三角剖分中的典型优化准则—最小内角最大准则提出了改进，按照改进后的优化准则实现了采样点的局部三角划分，并进一步求解得到采样点的法向量，依据法向量及邻域拓扑关系在二次曲面的基础上实现了散乱数据曲面重构中的数据点的自动分类。

Since the lengths of the line segments and the angles between line segments are treated as representation parameters, it is convenient to construct energy function and to deal with displacement and length constraints. Based on this advantage, a parametrical model for human body is proposed, which can easily produce human body models with different feature sizes. The above method is just suitable for polylines. Therefore, a generic deformation method for both discrete curves and surfaces is presented. The energy function is constructed by analyzing the relationship of the points before and after deformation. Together with the displacement constraints, the deformation problem is converted to a convex quadratic programming. A necessary condition for constraint points and a sufficient condition for the uniqueness of solution are given. The proposed method can be combined with skeleton-driven animation to control the deformation.

将线段长度与线段之间的角度作为表示参数，既有利于能量函数的构造，又便于处理位移约束和长度内蕴约束条件，利用这一优势，将其应用于三维人体的参数化建模，可以方便地产生具有不同特征尺寸参数的人体模型，由于这种方法只适用于折线变形，具有较大局限性，因此，本文进一步提出一种较通用的离散曲线曲面变形方法，通过分析变形前后的位置关系来构造能量函数，再加上位移约束条件，将变形问题转化为一个凸二次规划问题，并且给出了约束点应满足的必要条件及模型解唯一的充分条件，这种方法还可以与骨架驱动变形的思想相结合，能更好的控制变形。

The high vertical resolution is achieved at a larger sampling distance when interpolation algorithm is adopted to reconstruct the 3D profile and the conicoid fitting technique is used to calibrate for the system error in the data processing.

在数据处理上，采用了内插值三维重构算法，以及二次曲面拟合的系统误差校正算法，可以在较大的采样间距下获取较高的测量精度。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失