Fringe projection profilometry (FPP) is widely used in optical three-dimensional (3D) measurements because of its high stability. In FPP, fringe distortion is an inevitable and highly complex systematic error that significantly reduces the 3D measurement accuracy. At this point, the existing causes of fringe distortion represented by gamma distortion, high-order harmonics, and image saturation have been effectively analyzed and compensated to restore high-quality fringe images. In this paper, we innovatively reveal a concealed cause of fringe distortion, i.e., intensity diffusion across pixels, which is induced by photocarrier diffusion between photodiodes. To the best of our knowledge, intensity diffusion has not been studied in the field of fringe restoration. Based on the motion of photocarrier diffusion, we theoretically analyze the mechanism of how the intensity diffusion affects FPP. Subsequently, an intensity diffusion model is established for quantifying the diffused intensity in each pixel, and an intensity diffusion correction algorithm is presented to remove the diffused intensity from the fringe images and correct the fringe distortion. Experiments demonstrate the impact of intensity diffusion on FPP, and the 3D measurement results prove the effectiveness of the proposed methods on improving the 3D measurement accuracy by correcting the fringe distortion.

中文翻译：

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强度扩散：条纹投影轮廓测量中条纹失真的隐藏原因

条纹投影轮廓仪 (FPP) 因其高稳定性而广泛用于光学三维 (3D) 测量。在 FPP 中，条纹失真是不可避免的且高度复杂的系统误差，会显着降低 3D 测量精度。至此，以伽马畸变、高次谐波、图像饱和度为代表的条纹畸变的存在原因得到了有效的分析和补偿，恢复了高质量的条纹图像。在本文中，我们创新性地揭示了条纹失真的隐藏原因，即像素之间的强度扩散，这是由光电二极管之间的光载流子扩散引起的。据我们所知，在边缘修复领域尚未研究强度扩散。基于光载流子扩散的运动，我们从理论上分析了强度扩散如何影响 FPP 的机制。随后，建立了一个强度扩散模型来量化每个像素的扩散强度，并提出了一种强度扩散校正算法来去除条纹图像中的扩散强度并校正条纹失真。实验证明了强度扩散对FPP的影响，3D测量结果证明了所提出的方法通过校正条纹失真来提高3D测量精度的有效性。提出了一种强度扩散校正算法，去除条纹图像中的扩散强度，校正条纹畸变。实验证明了强度扩散对FPP的影响，3D测量结果证明了所提出的方法通过校正条纹失真来提高3D测量精度的有效性。提出了一种强度扩散校正算法，去除条纹图像中的扩散强度，校正条纹畸变。实验证明了强度扩散对FPP的影响，3D测量结果证明了所提出的方法通过校正条纹失真来提高3D测量精度的有效性。