DC-Reg: Globally Optimal Point Cloud Registration via Tight Bounding with Difference of Convex Programming

TL;DR

DC-Reg introduces a globally optimal point cloud registration method that employs a novel Difference of Convex programming approach to derive tight bounds, enabling faster and more robust registration under challenging conditions.

Contribution

The paper presents a new holistic DC decomposition for the coupled registration objective, improving lower bound tightness and efficiency in global point cloud registration.

Findings

Achieves faster convergence than existing methods.

Demonstrates robustness to noise and outliers.

Validates effectiveness on synthetic and benchmark datasets.

Abstract

Achieving globally optimal point cloud registration under partial overlaps and large misalignments remains a fundamental challenge. While simultaneous transformation ($\boldsymbol{\theta}$) and correspondence ($\mathbf{P}$) estimation has the advantage of being robust to nonrigid deformation, its non-convex coupled objective often leads to local minima for heuristic methods and prohibitive convergence times for existing global solvers due to loose lower bounds. To address this, we propose DC-Reg, a robust globally optimal framework that significantly tightens the Branch-and-Bound (BnB) search. Our core innovation is the derivation of a holistic concave underestimator for the coupled transformation-assignment objective, grounded in the Difference of Convex (DC) programming paradigm. Unlike prior works that rely on term-wise relaxations (e.g., McCormick envelopes) which neglect variable interplay, our holistic DC decomposition captures the joint structural interaction between $\boldsymbol{\theta}$ and $\mathbf{P}$. This formulation enables the computation of remarkably tight lower bounds via efficient Linear Assignment Problems (LAP) evaluated at the vertices of the search boxes. We validate our framework on 2D similarity and 3D rigid registration, utilizing rotation-invariant features for the latter to achieve high efficiency without sacrificing optimality. Experimental results on synthetic data and the 3DMatch benchmark demonstrate that DC-Reg achieves significantly faster convergence and superior robustness to extreme noise and outliers compared to state-of-the-art global techniques.