Quasi-calibration method for structured light system with auxiliary camera (2403.01119v1)

Abstract: The structured light projection technique is a representative active method for 3-D reconstruction, but many researchers face challenges with the intricate projector calibration process. To address this complexity, we employs an additional camera, temporarily referred to as the auxiliary camera, to eliminate the need for projector calibration. The auxiliary camera aids in constructing rational model equations, enabling the generation of world coordinates based on absolute phase information. Once calibration is complete, the auxiliary camera can be removed, mitigating occlusion issues and allowing the system to maintain its compact single-camera, single-projector design. Our approach not only resolves the common problem of calibrating projectors in digital fringe projection systems but also enhances the feasibility of diverse-shaped 3D imaging systems that utilize fringe projection, all without the need for the complex projector calibration process.

• The paper introduces a quasi-calibration method that eliminates complex projector calibration by using an auxiliary camera for high reconstruction accuracy.
• It employs a pixel-wise calibration model combining polynomial and rational functions to convert phase data into precise world coordinates.
• Experimental validation shows superior performance on flat planes, spheres, and complex geometries, reducing both system complexity and cost.

Quasi-Calibration Method for Enhancing 3D Reconstruction in Structured Light Systems

Introduction to Quasi-Calibration Method

Structured Light Systems (SLS) have long been a cornerstone in the field of 3D reconstruction, used extensively across various applications from manufacturing to medicine. These systems, notably those employing Digital Fringe Projection (DFP), have traditionally required intricate calibration of projectors to achieve high-accuracy 3D point clouds. This paper introduces an innovative calibration method that leverages an auxiliary camera to streamline the calibration process in SLS, particularly in DFP setups. By utilizing this quasi-calibration method, the need for complex projector calibration is eradicated, significantly simplifying the setup without compromising on the precision and quality of 3D reconstructions.

Methodology Overview

Theoretical Foundations

The paper outlines a detailed foundation of the Fringe Projection Profilometry (FPP) technique, highlighting its dependence on accurately calibrated optical devices for 3D reconstruction. It explores the N-step phase shifting method, emphasizing the role of phase instead of intensity for noise-tolerant reconstruction, which is less affected by surface reflectivity and texture color.

Calibration Method

The core of the proposed method is the introduction of an auxiliary camera during the calibration phase. This setup enables the generation of world coordinates from absolute phase information without the need for projector calibration. A pixel-wise calibration model, leveraging both polynomial and rational models, is developed to establish a precise relationship between phase values and world coordinates.

Experimental Validation

The methodology's efficacy is evaluated through rigorous experiments, encompassing the calibration of traditional setups and those with rough type illuminators. Reconstruction accuracy is meticulously assessed via the reconstruction of flat planes, spheres, and complex geometries, demonstrating the method's superiority over traditional calibration techniques both in terms of accuracy and operational simplicity.

Implications and Future Directions

This research not only presents a significant simplification in the calibration process of DFP systems but also opens avenues for the use of non-traditional, cost-effective illuminators in structured light systems. The practical implications are vast, extending the applicability of SLS across different domains while ensuring high reconstruction accuracy.

Theoretical Implications

From a theoretical standpoint, this paper advances the understanding of 3D reconstruction in FPP systems, especially highlighting the feasibility of quasi-calibration methods. It challenges the traditional calibration paradigms and paves the way for future research into simplified yet precise calibration methodologies for structured light systems.

Practical Implications

Practically, this method reduces the complexity and cost associated with setting up 3D reconstruction systems. By enabling the use of simpler, more accessible illumination devices without stringent calibration requirements, it has the potential to democratize high-quality 3D scanning technologies for a broader range of applications and users.

Future Developments

Looking ahead, exploring the integration of AI and machine learning techniques with this quasi-calibration approach could further enhance the accuracy and efficiency of 3D reconstruction. Additionally, expanding the method's applicability to dynamic, real-time reconstruction scenarios presents an exciting frontier for future exploration.

Concluding Remarks

The quasi-calibration method presented in this paper marks a significant advancement in the calibration of structured light systems. By simplifying the process and opening the door to the use of various illumination devices, it holds promise for broadening the accessibility and utility of high-accuracy 3D reconstruction technologies across multiple fields.