Huang Huiming, Liu Guihua, Deng Lei, Song Tao, Qin FuPing
College of information Engineering, Southwest University of Science and Technology, Mianyang, 621000, China.
Sci Rep. 2024 Oct 9;14(1):23589. doi: 10.1038/s41598-024-74331-6.
The traditional multi-line laser 3D reconstruction is based on binocular epipolar constraints and the equation of the laser optical plane. Firstly, matching points are identified based on the epipolar constraints. Then, the correct matching points are selected based on the optical plane equation of the multi-line laser. Finally, 3D reconstruction is performed using the selected matching points. In actual production processes involving multi-line lasers, noticeable distortion occurs due to the projection of Diffractive Optical Elements (DOE) at a large angle. This results in curved laser light planes and curved reflections on the measured objects. Under such circumstances, efficiently screening matching points using the traditional method based on the laser plane equation becomes challenging. Additionally, inherent noise in multi-line laser systems introduces errors in extracted laser center coordinates, making it impossible to directly obtain high-precision 3D data. To address these issues, this paper proposes a method that utilizes spatial quadric surfaces and geometric estimation for completing multi-line laser 3D reconstructions. By analyzing the distortion principle of DOE and the positional relationship after optical diffraction, the multi-line laser manifests as a quadric surface on the optical output plane. Consequently, by calibrating the equations of the quadric surface and applying binocular polar constraints, suitable matching points for the multi-line laser can be chosen. Once an accurate matching point is identified, a minimum geometric distance estimation can be established based on the distance constraint between the point and its corresponding epipolar line. This distance represents the separation between the left and right camera's laser center points and their respective epipolar lines. Utilizing this estimate of the minimum geometric distance, a refined calculation can be performed to better satisfy epipolar constraints and obtain new matching points. Ultimately, utilizing these new matching points enables the completion of 3D reconstruction for multi-line lasers. In comparison with methods relying on spatial plane and epipolar constraints, our algorithm exhibits a superior degree of matchability and accuracy.According to multiple groups of test data, the average error before optimization is 0.3126 mm, and can be increased to 0.0336 mm after optimization.
传统的多线激光三维重建基于双目极线约束和激光光学平面方程。首先，基于极线约束识别匹配点。然后，根据多线激光的光学平面方程选择正确的匹配点。最后，使用选定的匹配点进行三维重建。在涉及多线激光的实际生产过程中，由于衍射光学元件（DOE）大角度投影会出现明显的畸变。这导致激光光平面弯曲以及被测物体上的反射弯曲。在这种情况下，使用基于激光平面方程的传统方法有效筛选匹配点变得具有挑战性。此外，多线激光系统中的固有噪声会在提取的激光中心坐标中引入误差，从而无法直接获得高精度的三维数据。为了解决这些问题，本文提出一种利用空间二次曲面和几何估计来完成多线激光三维重建的方法。通过分析DOE的畸变原理和光衍射后的位置关系，多线激光在光输出平面上表现为二次曲面。因此，通过校准二次曲面方程并应用双目极线约束，可以选择适合多线激光的匹配点。一旦确定了准确的匹配点，就可以基于该点与其对应极线之间的距离约束建立最小几何距离估计。这个距离表示左右相机的激光中心点与其各自极线之间的间距。利用这个最小几何距离估计，可以进行精细计算以更好地满足极线约束并获得新的匹配点。最终，利用这些新的匹配点能够完成多线激光的三维重建。与依赖空间平面和极线约束的方法相比，我们的算法具有更高的匹配度和准确性。根据多组测试数据，优化前的平均误差为0.3126毫米，优化后可降至0.0336毫米。
