如果這是顯而易見的,我會提前道歉;我一直無法找到放入Google的正確條款。找到3D NURBS曲面的參數範圍的邊界框(軸向對齊)
我想要做的是爲修剪NURBS曲面上的任意參數範圍找到邊界體積(AABB足夠好)。例如,(u,v)在(0.1,0.2)和(0.4,0.6)之間。
編輯:如果有幫助,如果該方法將參數化區域完全限制在下面段落中定義的邊界區域內,那我就可以了。我有興趣對這些地區進行細分。
我開始思考這個從這一紙(http://www.cs.utah.edu/~shirley/papers/raynurbs.pdf),這也解釋瞭如何創建邊界體積的一棵樹,相對於表面的程度的深度閱讀本段後:
The convex hull property of B-spline surfaces guarantees that the surface is contained in the convex hull of its control mesh.
As a result, any convex objects which bound the mesh will bound the underlying surface. We can actually make a stronger
claim; because we closed the knot intervals in the last section [made the multiplicity of the internal knots k − 1], each nonempty
interval [ui; ui+1) [vj; vj+1) corresponds to a surface patch which is completely contained in the convex hull of
its corresponding mesh points. Thus, if we produce bounding volumes for each of these intervals, we will have completely
enclosed the surface. We form the tree by sorting the volumes according tothe axis direction which has greatest extent across the bounding volumes, splitting the data in half, and repeating the process.
謝謝! Sean