Luminaires - part 2 - 24 : particular requirements - luminaires with limited surface temperatures 灯具.第2 - 24部分:特殊要求.带有限表面温度的灯具
Luminaires . part 2 : particular requirements . section 24 : luminaires with limited surface temperatures 光源.第2部分:特殊要求.第24节:限制表面温度的光源
Luminaires - part 2 : particular requirements ; section 24 : luminaires with limited surface temperatures iec 60598 - 2 - 24 : 1997 , modified ; german version en 60598 - 2 - 24 : 1998 灯具.第2部分:特殊要求.第24节:限制表面温度的灯具
The problems include catmull - clark subdivision surfaces ca n ' t precisely represent standard conicoid except paraboloid , and it ca n ' t modify the shape of limited surfaces when the original control mesh be given 如: catmull - clark细分曲面无法精确表示除抛物面外的常规二次曲面;在给定初始控制网格的情况下,难以调整所生成曲面的形状等。
When parameter t unequal to zero the limited surfaces are proved at least c1 continuous except at extraordinary points . moreover , we can use this subdivision algorithm as pretreatment for catmull - clark subdivision . secondly , an adjustable catmull - clark subdivision algorithm based on c - b - splines is proposed 文中对这族细分曲面的性质进行了较详尽的分析,并证明了在参数t不等于零时这族曲面在非奇异点处至少具有c ~ 1连续。
The main innovation of our method is that we only need construct polygonal mesh possessing simple symmetric properties on both sides of control polygon edges of interpolated curves , and do n ' t need modify the subdivision rules near the interpolation curves during the process of subdivision . thus the subdivision rules are simple . the process is convergent and the limit surface is c everywhere except a finite number of points 该方法的主要创新思想是,在被插值曲线的控制多边形两侧构造具有简单对称性质的多边形网格,而在细分过程中,则无须修改被插值曲线附近的细分规则,凶此细分算法是简单的,细分过程是收敛的,且最终的插值曲面除有限个点外是c ~ 2连续的。
However most subdivision schemes do n ' t take the limit surface ' s convergence to some user - definded position parameters into account . so subdivision surfaces are always applied in computer animation and artware shape design , not in reverse engineering in which the position - setting constrains are appended to the result surfaces , precision machine design and medical image reconstruction 然而由于大多数细分算法不考虑极限曲面收敛到用户指定的某些位置参数,细分曲面的应用始终只能局限在计算机动画和工艺品设计,无法越雷池半步,应用到对曲面有定位约束要求的反求工程中,参与精密机械设计与医学图象重建。