arXiv:2509.22043cs.LGstat.ML2025-09

提出一种无边界点云降维方法,保留局部非凸结构。

Convexity-Driven Projection for Point Cloud Dimensionality Reduction

  • 基于邻近图识别低欧氏-最短路径比的点对,构建非凸性矩阵。
  • 投影使用矩阵前k个特征向量,保证点对间畸变上界可验证。
  • 提供可检查的误差量化指标,适合关注降维可靠性的人群。

我们提出凸性驱动投影(CDP),一种无边界的线性点云降维方法,旨在保留由绕行引发的局部非凸性。CDP 构建 $k$-NN 图,识别欧氏距离与最短路径比率低于阈值的可接受点对,并将其归一化方向聚合为半正定的非凸性结构矩阵。投影采用该矩阵的前 $k$ 个特征向量。本文给出两个可验证的保证:一对后验证书,用于限定每个可接受点对在投影后的畸变;以及平均情况下的谱界,将捕获的方向能量与结构矩阵的谱关联,得出典型畸变的分位数结论。评估协议报告固定对与重选对的绕行误差及证书分位数,使从业者可在其数据上验证保证。

原文摘要 · Abstract (English)

We propose Convexity-Driven Projection (CDP), a boundary-free linear method for dimensionality reduction of point clouds that targets preserving detour-induced local non-convexity. CDP builds a $k$-NN graph, identifies admissible pairs whose Euclidean-to-shortest-path ratios are below a threshold, and aggregates their normalized directions to form a positive semidefinite non-convexity structure matrix. The projection uses the top-$k$ eigenvectors of the structure matrix. We give two verifiable guarantees. A pairwise a-posteriori certificate that bounds the post-projection distortion for each admissible pair, and an average-case spectral bound that links expected captured direction energy to the spectrum of the structure matrix, yielding quantile statements for typical distortion. Our evaluation protocol reports fixed- and reselected-pairs detour errors and certificate quantiles, enabling practitioners to check guarantees on their data.

点云降维非凸性保留投影方法

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