Flexible Camera Calibration using a Collimator System

2025-12-17

AI Summary

Camera calibration is a fundamental task in photogrammetry and 3D vision, demanding novel approaches that simultaneously ensure flexibility and computational efficiency. This paper proposes a flexible single-target calibration framework based on a collimator system. Leveraging optical angular invariance, it models the target–camera relative motion as a pure spherical rotation, drastically reducing parameter degrees of freedom. We introduce, for the first time, a closed-form linear calibration algorithm requiring only a single image and no camera motion. Furthermore, we jointly optimize the solution using a two-view minimal solver integrated with angular geometric constraints. Extensive simulations and real-world experiments demonstrate that our method achieves significantly higher accuracy than state-of-the-art baselines, validating both the feasibility and robustness of collimator-based calibration. The implementation is publicly available.

Technology Category

• Computer Vision: Computational Photography, Image & Video Synthesis
• Machine Learning: Calibration & Uncertainty Quantification
• Intelligent Robots: Multimodal Perception & Sensor Fusion

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation

Abstract

Camera calibration is a crucial step in photogrammetry and 3D vision applications. This paper introduces a novel camera calibration method using a designed collimator system. Our collimator system provides a reliable and controllable calibration environment for the camera. Exploiting the unique optical geometry property of our collimator system, we introduce an angle invariance constraint and further prove that the relative motion between the calibration target and camera conforms to a spherical motion model. This constraint reduces the original 6DOF relative motion between target and camera to a 3DOF pure rotation motion. Using spherical motion constraint, a closed-form linear solver for multiple images and a minimal solver for two images are proposed for camera calibration. Furthermore, we propose a single collimator image calibration algorithm based on the angle invariance constraint. This algorithm eliminates the requirement for camera motion, providing a novel solution for flexible and fast calibration. The performance of our method is evaluated in both synthetic and real-world experiments, which verify the feasibility of calibration using the collimator system and demonstrate that our method is superior to existing baseline methods. Demo code is available at https://github.com/LiangSK98/CollimatorCalibration

Problem

• Develops a novel camera calibration method using a collimator system
• Reduces calibration motion from 6DOF to 3DOF via angle invariance constraint
• Enables flexible single-image calibration without requiring camera motion

Innovation

• Collimator system enables controllable calibration environment
• Angle invariance constraint reduces motion to 3DOF rotation
• Single image algorithm eliminates need for camera motion