曲线

Returns the parametric extents of the curve.

返回曲线的参数，参数相当于曲线终点。

However, no matter what free-form deformation based on extension factor for parametric curve or arbitrary partition will reduce smoothness of parametric curve.

然而，无论是基于伸缩因子的自由变形还是基于任意分割参数曲线的自由变形都会使参数曲线的光滑度降低。

This problem of planar parametric polynomial curve of degree 3 had been discussed perfectly many years ago, making use of invariant of affine transformation.

关于三次代数多项式参数曲线的这一问题早已解决，然而所用的几何不变量方法对于非代数曲线失效。

From commonly used equation of calculating plane figure quadrature, formulas of calculating plane figure quadrature by applying curve parametric equation can be deduced.

从由曲线普通方程求平面图形面积的公式出发推出在各种情形下由曲线参数方程求平面图形面积的公式。

ISO834 and parametric equation approach are lack of pertinence. The results may be too conservative. The temperature obtained by zone model is low, so that it is not suitable for the performance-based fire protection design on this structure. Field model considers the heterogeneity of environmental temperature, and its result is close to the real fire, so that it is commended to the performance-based fire protection design on steel staggered-truss structure.

国际标准升温曲线和参数化室内升温曲线不考虑火源功率、建筑通风口等因素，缺乏针对性，分析结果偏于保守；区域模型所得温度偏低，不宜用于交错桁架结构的性能化抗火设计；场模型考虑了火源功率及环境温度分布的不均匀性，和实际火灾较接近，计算结果相对较为准确，可用于结构的性能化防火设计。

The parametric representation of segment can be gained from quadratic patch and constrained equations with cubic patches.

利用二次曲面的参数形式，由三次曲面片可得到曲线的隐参数约束形式，从而得到曲线的参数形式。

Space curve is one of the basic elements in geometric modeling, and its effective representation is the basis of modeling. Parametric representation based on features is a kind of high-level representation including semantic information. In Chapter 4, para- metric representations based on features for free form space curve are investigated, and a parametric model for the loop of plain knitted fabric is established, in which 5 parameters with practical meanings are used to represent the shape of a loop and the relationship between loops. A new shrinkage prediction method for knitted fabric are proposed based on the parametric representation and energy minimizing. Experimental results on some plain knitted fabrics illustrate the feasibility of the proposed method.

空间曲线是造型中最基本的几何元素之一，对其有效的表示是造型的基础，而特征参数化表示是其中一种包含语义信息的高层次表示，本文对空间自由曲线的特征参数化表示进行研究，建立了一种针织物线圈的特征参数化几何模型，采用5个具有实际意义的参数表示织物线圈的几何形状及线圈之间的位置关系，并将该模型与能量极小化的方法相结合，得到了一种能较好地预测针织物缩水率的新模型，对随机选取的一些针织布缩水预测实验表明了算法的可行性。

The basic idea is as follows: with the help of the related results of differential geometry, the problem of interpolating curve on a parametric surface is converted to a similar one on its parametric plane.

基本思想是借助于微分几何的有关结论，曲面上曲线的插值问题被转化为其参数平面上类似的曲线插值问题。

First, structure tensor is calculated to gain vector field for characterizing local structure of image. And then, total variation partial difference equation is imposed for smoothing vector field. Based on this we use line integral convolution for guide the stroke to generate virtual special effect image with fluctuant sense. Last, mergering with original real image, cylindrical panorama with virtualized relationship controlled by time can be generated, which accomplished the character of surpass the time and space in virtual reality system.

该方法通过计算结构张量获得图像曲线走向矢量场，以此刻画图像局部结构；并采用全变分偏微分方程对曲线走向矢量场自适应滤波平滑处理；在此基础上利用线积分卷积指导画笔走向模拟生成线条波动感虚化效果图像；最后结合原始真实图像和虚化效果图像，实现了一种基于时间变量的柱面场景虚化关联算法，并为虚拟现实系统超越现实时空的需要提供了一种新思路。

Based on the algorithm principle of curve,taking the Bezier curve for example,in the condition of VC++ 6.0,through creating the virtual grid and simulating the computer's pels points,with the alternant control technology and the visualization technology,a brand-new visualization teaching demonstration system of computer graphics is developed.

以开发具有更加良好认知意义的教学软件为目标，摒弃了计算机图形学传统的教学方式，从曲线的算法原理出发，以Bezier曲线为例，在VC++6.0的开发环境中，通过建立虚拟栅格和模拟计算机的"像素点"，运用了交互控制技术，动态演示的可视化技术，开发出了一套全新的计算机图形学可视化教学演示系统。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。