Hierarchical B-spline refinement
Hierarchical B-spline refinement
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DOI：
10.1145/54852.378512
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发表时间：
1988-06
期刊：
影响因子：
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通讯作者：
D. Forsey;R. Bartels
中科院分区：
文献类型：
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作者：
D. Forsey;R. Bartels
精细化通常被认为是在编辑过程中对样条曲线或曲面进行更精细控制的一种手段。对于曲线，细化是一个局部过程。它允许在曲线的一个区域更改控制顶点并随后编辑细节，而不影响其他区域的控制顶点。然而，对于张量积曲面，细化不是局部的，因为它导致远离感兴趣区域的控制顶点改变，以及改变影响该区域的控制顶点。但是，通过一些谨慎和理解，可以将精化的影响限制在需要编辑效果的位置。我们提出了一种通过使用分层控制细分的覆盖来定位细化效果的方法。我们还介绍了在使用覆盖时有效的两种编辑技术：一种是通过使用编辑点直接对表面进行操作，另一种是对控制顶点进行偏移引用。
Refinement is usually advocated as a means of gaining finer control over a spline curve or surface during editing. For curves, refinement is a local process. It permits the change of control vertices and subsequent editing of the detail in one region of the curve while leaving control vertices in other regions unaffected. For tensor-product surfaces, however, refinement is not local in the sense that it causes control vertices far from a region of interest to change as well as changing the control vertices that influence the region. However, with some care and understanding it is possible to restrict the influence of refinement to the locality at which an editing effect is desired. We present a method of localizing the effect of refinement through the use of overlays, which are hierarchically controlled subdivisions. We also introduce two editing techniques that are effective when using overlays: one is direct surface manipulation through the use of edit points and the other is offset referencing of control vertices.