Adaptive digital fringe projection technique for high dynamic range three-dimensional shape measurement
Adaptive digital fringe projection technique for high dynamic range three-dimensional shape measurement
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DOI：
10.1364/oe.24.007703
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发表时间：
2016-04-04
期刊：
影响因子：
3.8
通讯作者：
Wang, Xingjin
中科院分区：
文献类型：
--
作者：
Lin, Hui;Gao, Jian;Wang, Xingjin
对于任何光学方法来说，测量具有大范围反射率变化的物体都是一个挑战。图像饱和导致捕获的条纹图案图像中的不正确强度，从而导致相位和测量误差。本文提出了一种新的自适应数字条纹投影技术，它避免了图像饱和，并具有较高的信噪比（SNR）的三维（3-D）的形状测量的对象，有一个大的范围内的反射率变化的表面。与以前的高动态范围的3-D扫描方法，使用许多曝光和条纹图案的投影，这消耗了大量的时间相比，所提出的技术只使用两个初步步骤的条纹图案的投影和图像捕获，以产生自适应的条纹图案，通过自适应地调整像素的投影条纹图案的强度的基础上的饱和像素在被测量的表面的捕获图像。对于由于高表面反射率和由环境光和表面互反射的高照明而导致的亮区域，投影强度被减小到足够低以避免图像饱和。同时，255的最大强度用于具有低表面反射率的那些暗区域以保持高SNR。我们的实验表明，所提出的技术可以实现更高的三维测量精度在整个表面的反射率变化范围很大。(C)2016美国光学学会
It is a challenge for any optical method to measure objects with a large range of reflectivity variation across the surface. Image saturation results in incorrect intensities in captured fringe pattern images, leading to phase and measurement errors. This paper presents a new adaptive digital fringe projection technique which avoids image saturation and has a high signal to noise ratio (SNR) in the three-dimensional (3-D) shape measurement of objects that has a large range of reflectivity variation across the surface. Compared to previous high dynamic range 3-D scan methods using many exposures and fringe pattern projections, which consumes a lot of time, the proposed technique uses only two preliminary steps of fringe pattern projection and image capture to generate the adapted fringe patterns, by adaptively adjusting the pixel-wise intensity of the projected fringe patterns based on the saturated pixels in the captured images of the surface being measured. For the bright regions due to high surface reflectivity and high illumination by the ambient light and surfaces interreflections, the projected intensity is reduced just to be low enough to avoid image saturation. Simultaneously, the maximum intensity of 255 is used for those dark regions with low surface reflectivity to maintain high SNR. Our experiments demonstrate that the proposed technique can achieve higher 3D measurement accuracy across a surface with a large range of reflectivity variation. (C) 2016 Optical Society of America