Fringe Projection Profilometry (FPP) faces challenges with objects of varying surface reflectivity, as projected light can exceed the camera’s dynamic range, hindering effective fringe capture. Current solutions using repeated projections with varying exposures increase measurement time, limiting real-time applicability. This study validates deep neural networks that transform traditional multi-frequency, multi-step, multi-exposure methods into a single-step, multi-exposure format, significantly reducing measurement time while maintaining accuracy. Experimental results demonstrate that deep learning methods can effectively extract phase information from modulated fringe images, unwrap it, and reconstruct 3D point clouds. On high-reflectivity metal datasets, the accuracy of the deep learning approach closely matches that of the traditional six-step method, while using only 16.7% of the time. For standard objects, the accuracy reaches up to 60 microns. These findings confirm that various deep learning methods can efficiently resolve phase information in modulated fringe patterns, significantly enhancing measurement speed.
KEYWORDS: High dynamic range imaging, Fringe analysis, Deep learning, Cameras, 3D metrology, Projection systems, Optical spheres, Reflectivity, Neural networks, Metals
Fringe projection profilometry (FPP) technology, renowned for its stable and high-precision characteristics, is widely employed in three-dimensional surface measurements of objects. Whether utilizing deep learningbased methods or traditional multi-frequency, multi-step fringe analysis techniques, both require acquiring highquality stripe patterns modulated by the three-dimensional surface of the object. However, the limited dynamic range of cameras makes it difficult to capture effective fringe information in a single exposure, and while multiexposure methods can address this issue, they are inefficient. To address this, this study proposes an end-to-end neural network approach for generating high dynamic range (HDR) fringe patterns from projected gratings. Additionally, an end-to-end network is employed to solve the fringe phase. Experimental results demonstrate that this method significantly improves fringe pattern recovery on metallic surfaces with overexposed or underexposed regions. On a high dynamic range reflectivity dataset, the method achieved a phase error of 0.02072, successfully reconstructing 3D objects with only 8.3% of the time required by the 12-step Phase Shifting Profilometry (PSP) method. Furthermore, on standard spherical and planar objects, the method achieved a radius accuracy of 53.1 μm and flatness accuracy of 61.7 μm, demonstrating effective measurement precision without the need for additional steps. This method is effective for both high dynamic range reflective and non-high dynamic range reflective objects.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.