曲线图形

Many subdivision schemes have been proposed in the recent three decades, however, most of them are not capable of both reproducing families of curves widely used in Computer Graphics such as conics, and controlling the shape of the limit curve by a tension parameter.

近三十年来已有多种细分方法被相继提出，然而大多数细分方法不能既生成在计算机图形学中广泛应用的特殊曲线，例如圆弧曲线，又存在一个松弛参数能够调整极限曲线的形状。

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。

Research on basic algorithms of Computer Graphics has deep significance, because each application generally need numerous call of the basic algorithms. The speed and quality of generating a picture are tremendously affected by that of generating each line or curve. This paper researches the basic algorithms of Computer Graphics including the algorithms of drawing and clipping of lines and curves both on the square grid and the hexagonal grid.

对计算机图形学基础算法的研究具有重要意义，因为在具体应用中，每一幅图形都由成百上千条直线和曲线构成，这样对于每一条直线或曲线的处理速度和质量就极大地影响着整幅图形的处理速度和质量，本文的工作是对计算机图形学中的基础算法进行研究。

In this paper it is given a more effective formula about the direction angle of the main plane in the plane stress state.2. To introduce the principle and method for drawing 3-D graph with the compuer and for checking up with the computer cursor,to give outline of expressions of 3-D curve,outline of cursor meterage of well depth,well deflection angle and direction angle at any section.

介绍了在实践中总结出的计算机绘制与光标检测3维图形的原理和方法，给出了3维动态图形到屏幕坐标的变换式、各测点的平滑连接方法以及描绘与检测井眼轨迹曲线的典型应用，实现了空间井眼轨迹曲线的任意旋转、投影和给出了任一井段的井深、井斜角和方位角的光标检测软件。

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。

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。

The study establishes the compression of models and algorithms for vector graphics data on different basis, including on the basis of vector graphic factors of B spline curves in predecessors research; on the basis of rectangle graphic factors in main axis mode; on the basis of the application of Hough transform to polygonal line, ellipse and circle, so the study improves the models and algorithms of compression for vector graphic data.The compression for vector graphic data mainly studies the data of storing graphic factors.

本文研究的内容是：根据对以往各种曲线矢量数据压缩模型与算法的研究，建立了基于B样条的曲线矢量图形要素的数据压缩模型和算法；在前人研究的基础上，建立基于主轴模式的矩形图形要素的数据压缩模型和算法；本文作者将Hough变换应用到折线、圆及椭圆图形要素的矢量数据压缩上，在此基础上改进了基于Hough变换的折线、圆及椭圆图形要素的数据压缩模型和算法。

MethodsTwenty volunteers with normal hearing level and tympanic pressure were enrolled and kept at airtight container. The inner pressure was changed to 2 kPa and 4 kPa below normal atmospheric pressure in 50 s and recovered to the normal pressure, the pure tune hearing threshold of 500, 1 000 and 2 000 Hz and tympanic pressure were measured, and acoustic impedance curve characteristic and tympanic membrane appearance were recorded at each time points.

方法选取听力和鼓室压力正常的受试者20例，即单耳40耳，评估其于50s改变密闭模拟电梯容器压力低于正常大气压2kPa、50s改变密闭容器压力低于正常大气压4kPa、以及压力恢复至正常水平时，言语频率500、1000、2000Hz的纯音听阈，鼓室压值和声阻抗曲线图形形态，以及鼓膜形态。

Content : the concept of computer graphics, development, application and software and hardware systems; Line, circle, oval basic graphics generation, curve and regional filling; The projection geometry and transform; Graphics cutting, blan

内容为：计算机图形学的概念、发展、应用和软、硬件系统；直线、圆、椭圆基本图形的生成、曲线及区域的填充；几何图形的投影与变换；图形裁剪、消隐处理；光照模型和图案映射等真实感生成技术，并用VC++进行交互式图形设计实例。

In fact, Computer Graphics indicate the developmental level of the Computer software and hardware, This is because Graphics have become the most important medium to transfer all kinds of information. Computer Graphics?research object is graphics, and the point , line and surface make up of the graphics ,In addition, During the real application, every graphics is made up of millions of the lines and curves, the speed and quality of the line and curve affected the implement of the whole graphics.

计算机图形学的研究对象是图形，而构成图形的几何要素就是刻画形状的点、线、面、体等，并且在具体应用中，每一幅图形都由成百上千条直线和曲线构成，这样对于每一条直线或曲线的处理速度和质量极大地影响着整幅图形的处理速度和质量，因此，对于计算机图形学基础算法的研究就具有重要意义，本文就是对计算机图形学的基础算法进行研究，包括直线和曲线的生成和裁剪算法以及基本象素的图形变换。

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。