用非均匀细分模式构造N边域曲面

给出了用非均匀Catmu ll-C lark细分模式产生N边域曲面的两种方法。非均匀Catmu ll-C lark细分模式被推广到了开网格,如何产生带有B样条边界的N边域曲面是论述的重点。所建构的N边域曲面分为两类:不插值于网格角点的曲面和插值于网格角点的曲面。为了得到这样的曲面,需要对网格边界附近那些边所对应的参数进行相应的平均化,然后运用非均匀情形下的轮廓删除法可以产生第一类曲面,通过在边界附近的正则子网上采用新的细分规则能够产生第二类曲面。这两种构造N边域曲面的方法为NURBS曲面中N边洞的填充与NURBS曲面的混合提供了一个思路。

Constructing N-sided Patches Using Non-uniform Subdivision Schemes

The paper presents two methods for constructing N-sided patches using non-uniform Catmull-Clark subdivision scheme.The subdivision scheme is generalized to open meshes and emphasizes how to produce N-sided patches with B-spline boundaries.The constructed patches are classified as follows: patches non-interpolating corner vertices and patches interpolating corner vertices.To obtain these patches,edge parameters need to be averaged accordingly——the edges which are around boundaries.On this basis,patches of the first type can be produced by the skirt-removed approach for non-uniform Catmull-Clark subdivision scheme,and patches of the second type can be obtained by applying new subdivision rules on regular sub-meshes around boundaries.The two methods present a way of thinking for filling N-sided holes and blending NURBS surfaces.