Ren Hongyu, Gao Feng, Jiang Xiangqian
Appl Opt. 2015 Dec 1;54(34):10249-55. doi: 10.1364/AO.54.010249.
Stereo deflectometry is defined as measurement of the local slope of specular surfaces by using two CCD cameras as detectors and one LCD screen as a light source. For obtaining 3D topography, integrating the calculated slope data is needed. Currently, a high-order finite-difference-based least-squares integration (HFLI) method is used to improve the integration accuracy. However, this method cannot be easily implemented in circular domain or when gradient data are incomplete. This paper proposes a modified easy-implementation integration method based on HFLI (EI-HFLI), which can work in arbitrary domains, and can directly and conveniently handle incomplete gradient data. To carry out the proposed algorithm in a practical stereo deflectometry measurement, gradients are calculated in both CCD frames, and then are mixed together as original data to be meshed into rectangular grids format. Simulation and experiments show this modified method is feasible and can work efficiently.
立体偏折测量法的定义是，通过使用两个电荷耦合器件（CCD）相机作为探测器以及一个液晶显示屏（LCD）作为光源来测量镜面表面的局部斜率。为了获取三维地形，需要对计算出的斜率数据进行积分。目前，一种基于高阶有限差分的最小二乘积分（HFLI）方法被用于提高积分精度。然而，该方法在圆形区域或梯度数据不完整时不易实现。本文提出了一种基于HFLI的改进的易于实现的积分方法（EI - HFLI），它可以在任意区域工作，并且能够直接且方便地处理不完整的梯度数据。为了在实际的立体偏折测量中执行所提出的算法，在两个CCD帧中计算梯度，然后将它们混合在一起作为原始数据，网格化成矩形网格格式。仿真和实验表明，这种改进方法是可行的，并且能够高效工作。
