# High-Precision Extrinsic Calibration for Multi-LiDAR Systems with Narrow FoV via Synergistic Planar and Circular Features

## TL;DR

This paper introduces a high-precision method for calibrating multiple LiDAR systems using planar and circular features, improving accuracy and reducing reliance on manual steps.

## Contribution

A novel extrinsic calibration method for multi-LiDAR systems using synergistic planar and circular features, achieving high precision without manual intervention.

## Key findings

- Rotational and translational errors were contained within 0.08° and 0.8 cm in simulations.
- The method outperformed conventional point-cloud registration techniques in real-world experiments.

## Abstract

Precise extrinsic calibration is a fundamental prerequisite for data fusion in multi-LiDAR systems. However, conventional methods are often encumbered by dependencies on initial estimates, auxiliary sensors, or manual feature selection, which renders them complex, time-consuming, and limited in adaptability across diverse environments. To address these limitations, this paper proposes a novel, high-precision extrinsic calibration method for multi-LiDAR systems with a narrow Field of View (FoV), achieved through the synergistic use of circular and planar features. Our approach commences with the automatic segmentation of the calibration target’s point cloud using an improved VoxelNet. Subsequently, a denoising step, combining RANSAC and a Gaussian Mean Intensity Filter (GMIF), is applied to ensure high-quality feature extraction. From the refined point cloud, planar and circular features are robustly extracted via Principal Component Analysis (PCA) and least-squares fitting, respectively. Finally, the extrinsic parameters are optimized by minimizing a nonlinear objective function formulated with joint constraints from both geometric features. Simulation results validate the high precision of our method, with rotational and translational errors contained within 0.08° and 0.8 cm. Furthermore, real-world experiments confirm its effectiveness and superiority, outperforming conventional point-cloud registration techniques.