Yin Xiao-Qia, Tao Wei, Feng Yi-Yang, Gao Qiang, He Qiao-Zhi, Zhao Hui
Appl Opt. 2017 Apr 1;56(10):2653-2660. doi: 10.1364/AO.56.002653.
A line-structured laser scanner is widely applied for 3D reconstruction in industrial environments with ubiquitous various luminance, complicated background, diverse objects, and instable lasers. These elements will show up as noise in the obtained laser stripe images. Therefore, the basic and key point for a line-structured laser scanner is to accurately extract the laser stripe from noise. This paper proposes an effective laser stripe extraction procedure with two steps. First, a novel laser stripe center extraction method based on the geometry information and correlation in the laser stripe, is designed to significantly eliminate noise and accurately extract the laser stripe centers. In addition, the robustness, speed, and accuracy of this method are respectively analyzed in detail. Second, piecewise fitting is adopted to acquire a smooth and continuous laser stripe centerline. In order to select the optimal fitting method, the characteristics of two spline methods, Akima spline and cubic Hermite spline, are deeply analyzed and compared. Finally, an experiment is carried out by using a rough metal step and a line-structured laser scanning system. The experiment results demonstrate that the proposed self-adaptive convolution-mass method can significantly eliminate noise in industrial environments. In addition, the cubic Hermite spline is a better choice for 3D reconstruction, rather than the Akima spline.
线结构激光扫描仪广泛应用于工业环境中的三维重建，该环境中存在各种亮度、复杂背景、多样物体以及不稳定的激光。这些因素会在获取的激光条纹图像中表现为噪声。因此，线结构激光扫描仪的基础和关键在于从噪声中准确提取激光条纹。本文提出了一种有效的分两步进行的激光条纹提取方法。首先，设计了一种基于激光条纹几何信息和相关性的新型激光条纹中心提取方法，以显著消除噪声并准确提取激光条纹中心。此外，还分别详细分析了该方法的鲁棒性、速度和准确性。其次，采用分段拟合来获取平滑连续的激光条纹中心线。为了选择最优拟合方法，深入分析并比较了两种样条方法（秋山样条和三次埃尔米特样条）的特性。最后，使用粗糙金属台阶和线结构激光扫描系统进行了实验。实验结果表明，所提出的自适应卷积质量法能够显著消除工业环境中的噪声。此外，对于三维重建而言，三次埃尔米特样条比秋山样条是更好的选择。
