Projection-based coupling of infrared thermography and stereocorrelation-based digital image correlation

2026-06-27

AI Summary

This study addresses the challenge of fusing infrared thermography and stereo digital image correlation (DIC) data on non-planar surfaces. By employing an external projection approach based on the pinhole camera model, the method accurately maps the two-dimensional temperature field measured by infrared imaging onto the three-dimensional spatial points obtained from DIC, thereby coupling thermal and deformation fields within a unified Lagrangian coordinate framework. The projection matrices of the two independent calibration systems are determined using only a single reference image. Furthermore, spatiotemporal radial basis function interpolation is introduced to efficiently compute temperature gradients and temporal rates of change over curved surfaces. This approach integrates seamlessly into existing experimental workflows, enabling the generation of high-fidelity, full-field datasets enriched with comprehensive thermomechanical information.

Abstract

Full-field measurement techniques such as digital image correlation and infrared thermography are prevalent in experimental solid mechanics. Digital image correlation is used to analyze surface deformation, while infrared thermography quantifies surface temperature fields. However, sophisticated procedures are necessary to express both datasets in the same Lagrangian frame, especially when analyzing non-flat surfaces. In this study, we propose an external projection-based coupling that uses the pinhole camera model to relate two-dimensional temperature data measured by infrared thermography to three-dimensional point coordinates from stereocorrelation-based digital image correlation. Unlike existing multiview approaches, we utilize two independently calibrated industrial-grade systems and augment the experimental evaluation with the pinhole camera model. The projection matrix of the camera model is calibrated using a single image of a reference object. Through this projection, temperature fields are accurately represented at material points. Our method is particularly suited for, but not restricted to, curved surfaces and straightforward to embed in existing experimental protocols, as the image registration is kept as is. Additionally, we propose using radial basis functions as a global interpolation ansatz in both space and time to compute in-plane temperature gradients and even temperature rates on curved surfaces, thereby providing an extensive and information-rich full-field dataset.

Problem

• infrared thermography
• digital image correlation
• Lagrangian frame
• non-flat surfaces
• full-field measurement

Innovation

• projection-based coupling
• infrared thermography
• digital image correlation
• pinhole camera model
• radial basis functions