Decomposing the Complement of the Union of Cubes and Boxes in Three Dimensions

Pub Date : 2024-03-02 DOI:10.1007/s00454-024-00632-2
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Abstract

Let \(\mathcal {C}\) be a set of n axis-aligned cubes of arbitrary sizes in \({\mathbb R}^3\) in general position. Let \(\mathcal {U}:=\mathcal {U}(\mathcal {C})\) be their union, and let \(\kappa \) be the number of vertices on \(\partial \mathcal {U}\) ; \(\kappa \) can vary between O(1) and \(\Theta (n^2)\) . We present a partition of \(\mathop {\textrm{cl}}({\mathbb R}^3\setminus \mathcal {U})\) into \(O(\kappa \log ^4 n)\) axis-aligned boxes with pairwise-disjoint interiors that can be computed in \(O(n \log ^2 n + \kappa \log ^6 n)\) time if the faces of \(\partial \mathcal {U}\) are pre-computed. We also show that a partition of size \(O(\sigma \log ^4 n + \kappa \log ^2 n)\) , where \(\sigma \) is the number of input cubes that appear on \(\partial \mathcal {U}\) , can be computed in \(O(n \log ^2 n + \sigma \log ^8 n + \kappa \log ^6 n)\) time if the faces of \(\partial \mathcal {U}\) are pre-computed. The complexity and runtime bounds improve to \(O(n\log n)\) if all cubes in \(\mathcal {C}\) are congruent and the faces of \(\partial \mathcal {U}\) are pre-computed. Finally, we show that if \(\mathcal {C}\) is a set of arbitrary axis-aligned boxes in \({\mathbb R}^3\) , then a partition of \(\mathop {\textrm{cl}}({\mathbb R}^3\setminus \mathcal {U})\) into \(O(n^{3/2}+\kappa )\) boxes can be computed in time \(O((n^{3/2}+\kappa )\log n)\) , where \(\kappa \) is, as above, the number of vertices in \(\mathcal {U}(\mathcal {C})\) , which now can vary between O(1) and \(\Theta (n^3)\) .

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分解立方体和正方体的三维联合补集
Abstract Let \(\mathcal {C}\) be a set of n axis-aligned cubes of arbitrary sizes in \({\mathbb R}^3\) in general position.让(\mathcal {U}:=\mathcal {U}(\mathcal {C}))成为它们的联合,让(\kappa \)成为(\partial \mathcal {U})上的顶点数;(\kappa \)可以在O(1)和(\Theta (n^2))之间变化。我们将({mathop {textrm{cl}}({mathbb R}^3\setminus \mathcal {U}))划分为(O(\kappa \log ^4 n)\)个轴对齐的盒子,这些盒子的内部是成对的。如果预先计算好了(partial \mathcal {U})的面,那么就可以在(O(n \log ^2 n + \kappa \log ^6 n)时间内计算出这些面。我们还证明了一个大小为 \(O(\sigma \log ^4 n + \kappa \log ^2 n)\) 的分区。如果预先计算了 \(\partial \mathcal {U}\) 的面,那么可以在 \(O(n \log ^2 n + \sigma \log ^8 n + \kappa \log ^6 n)\)时间内计算出一个分区,其中 \(\sigma \)是出现在 \(\partial \mathcal {U}\) 上的输入立方体的数量。如果 \(\mathcal {C}\) 中的所有立方体都是全等的,并且 \(\partial \mathcal {U}\) 的面都是预先计算的,那么复杂度和运行时间的边界就会提高到 (O(n\log n)\)。最后,我们证明如果 \(\mathcal {C}\) 是 \({\mathbb R}^3\) 中任意轴对齐盒的集合 、那么可以在(O((n^{3/2}+\kappa )\log n)\)的时间内将\({textrm{cl}}({mathbb R}^3\setminus \mathcal {U}))分割成\(O(n^{3/2}+\kappa )\)个盒子。其中,\(\kappa\)和上面一样,是\(\mathcal {U}(\mathcal {C})\) 中顶点的数量,现在可以在O((n^{3/2}+\kappa)\log n)之间变化。现在可以在 O(1) 和 (Theta (n^3)\) 之间变化。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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