拐点

3D reconstruction is one of the most challenging problems in computer vision. This project uses CAD model to increase the accuracy,robustness and speed of 3D reconstruction and five different works are conducted: 1 research on space curve 3D reconstruction method based on high curvature point nad turning point; 2 free-form curve 3D reconstruction based on B-spline and BURBS; 3 Active surface affine reconstruction based on single frame; 4 Matching and reconstruction of 3D sparse points; Data fitting method based on the iteration of nearest point.

三维重建是计算机视觉中公认的难题，本项目使用CAD模型来提高三维重建的精度、稳健性和速度的思路，围绕着空间曲线和曲面的三维重建和匹配开展了以下五个方面的研究：1）基于高曲率点和拐点分割的空间曲线三维重建方法研究；2）基于B样条和NURBS表示的空间自由曲线三维重建方法研究；3）基于单帧图像的有源曲面仿射重建；4）三维离散数据的匹配与重建；5）基于迭代最近点的数据拟合方法。

In this paper, the method, which is based on the theory of envelope and continuous map, is investigated.

文中用此方法分析了一些曲线的重要几何性质，即曲线段上含有尖点、重结点和拐点以及不含这些点的用控制顶点相对位置表示的充分必要条件。

There was no obvious correlation between the first extreme point of curvature location and the pain relief.

有效病例与无效病例组间拐点与第二曲率极值点位置不同，差异有显著性意义，第一曲率极值点两组间差异无显著性意义。

In the last part of the paper, we construct a family of 2 parameter cubic algebraic curves interpolating two given endpoints and two given tangent lines and two given curvatures at these two endpoints with different initial cases in detail.

引 言三次参数曲线在计算机辅助几何设计与计算机图形学领域一直扮演着十分重要的角色，这主要是由于三次参数曲线是具有奇异性的次数最低的曲线，这些奇异性包括尖点、拐点和闭圈。

Though several leak detecting methods are available, they are not ideal inapplication scope, including responses speed and accuracy of leak localization. In thisdissertation, according to the conditions of pipeline transportation in our country,research is carried out on crude oil transported pipelines leak detection and locationtheory and the study on its supervisory system is given.

本文结合我国管道输送的实际情况，针对原油管道泄漏检测技术及其运行监测系统进行了深入的研究，主要进行了以下几个方面的工作：将小波变换技术引入到负压波特征拐点的捕捉，利用连续小波变换时间-尺度特性检测信号的奇异点，能够有效的检测出强噪声背景下的信号边沿，此外，还提出了负压波法泄漏检测中误报警消除的多种方法。

The first rank derivative is a reflection of curve change and its rate, at certain range, if the sign of the first rank derivative has changed, the logging value of the correspondence depth point means maximum in this range; the second rank derivative is the knaggy property reflection of curve, at certain range, if the sign of the second rank derivative has changed, the correspondence depth point represent the inflexion of geophysical logging curve, it＇s also a turning point of the reflection of knaggy change property of the curve, it is the interface of stratum.

测井曲线的值是深度的函数，测井曲线的一阶导数表示了曲线变化的趋势和变化的快慢，在某一范围内，当一阶导数呈现符号转换时，相对应的深度点的测井值即为该范围内极大值；测井曲线的二阶导数则表示曲线的凹凸性，在某一范围内，当二阶导数呈现符号转换时，相对应的深度点代表了测井曲线的拐点，即反映曲线凹凸性变化的转折点，亦即地层的分界面。

An S-shape acceleration/deceleration control model is developed by summation progression and the corner of two conjoint lines is adopted as a parametric variable to control the feedrate through the inflexion of two lines. Based on these, interpolation process is divided into two steps: interpolation pretreatment and interpolation point calculation. Feedrate planning is accomplished in the pretreatment step. Interpolation point calculating only depends on the real-time feedrate and the direction vector of the line.

该算法以级数求和的方法推导了S型加减速控制模型，并以小线段夹角为参变量控制拐点通过速度建立了小线段速度衔接模型，在此基础上，算法将插补过程分解为插补预处理及插补点计算两个步骤，预处理中对小线段进行速度规划并设计了线段速度的递推处理方法，插补点仅需根据当前速度及线段方向向量即可求出。

It is to calculate the speed of machine tool on PC,and find out the inflexions and the slowdown point s,then transmit these datas to the DSP to control the machine tool.

设计思想是：在上位机上进行预处理，计算出数控机床沿轨迹各点的速度，判断轨迹的连续性，并找出轨迹中的&拐点&和减速点，然后将这些数据传给下位机对机床进行运动控制。

For feature extraction, this dissertation studies Barnard algorithm for Edge Point extraction and SUSAN algorithm for Corner extraction, Afterward, I put forward a method to extract inflexions, straight lines and curves based on Freeman Differential Code. Thus the use of Freeman Code can be extended and there will be more approaches to finish stereo correspondence.

在特征提取部分，本文对传统的Barnard边缘点提取、新近的SUSAN角点检测等技术做了详细的分析和研究，并在此基础上提出了基于Freeman差分码的多特征提取方法，包括拐点、直线及曲线，而且提取的直线利用多直线段分解法进行拟合，提取的曲线利用B样条技术进行拟合，最终形成有意义的轮廓。

The results showed S curve for effects of NaCl stress on germination of watermelon seed, the middle point between two inflexions of the curve was at 120mmol/L and could be used as referenced screening concentration to study 'ZQK0395' salt tolerance genetics, the second curve inflexion was at 180mmol/L and could be used as referenced concentration for 'ZQK0395' salt-tolerant germplasm selection.

结果表明，NaCl胁迫对种子发芽的影响呈S型变化曲线，120mmol/L为S型曲线两个拐点中间值，可作为该种质资源耐盐性遗传研究的参考鉴定浓度，180mmol/L为S型曲线的第二个拐点，可作为该种质资源耐盐性参考筛选浓度。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。