自由曲面的消隐、浓淡和阴影算法的研究

对消隐、浓淡和阴影处理问题进行了系统的研究，提出了一些新的算法。在消隐处理中，采用了类似Ｚ—Ｂｕｆｆｅｒ的消隐算法，并提出了根据曲面片的几何特性自动求取曲面片双参数步长的方法，从而提高了消隐速度。在浓淡处理中，采用菱形法计算α角并计及了相对距离的影响，使图形更具有逼真效果。在ＳｈａｄｏｗＺ－Ｂｕｆｆｅｒ阴影算法的基础上，建立了一个圆锥阴影模型，设计了一种新的阴影算法。利用这一模型和算法可以很方便地产生任何物体在平面上的阴影。

Research on Algorithms or Free-formed Surfaces'Eliminating,Shading and Shadow

Problems of free-formed surfaces'eliminating, shading and shadow are systematically researched in this paper and some of new algorithms are presented. Although the eliminating algorithm is similar to Z-Buffer algorithm,an automatical method of determining two parameter steps of every surface patch,according to its geometrical property, is presented. In the illumination model, the angle a. is calculated by means of rhombus-method and the concept of relative distance is applied,then the picture can be made more realistic. Through analysing Shadow Z-Buffer algorithm, a Cone-Shadow Model is set up and a new shadow algorithm is presented,and any object'S shadow on a plane will be obtained.