汕头大学 工学院 机械工程系, 广东 汕头 515063
视差不连续区域和重复纹理区域的误匹配率高一直是影响双目立体匹配测量精度的主要问题,为此,本文提出一种基于多特征融合的立体匹配算法。首先,在代价计算阶段,通过高斯加权法赋予邻域像素点的权值,从而优化绝对差之和(Sum of Absolute Differences,SAD)算法的计算精度。接着,基于Census变换改进二进制链码方式,将邻域内像素的平均灰度值与梯度图像的灰度均值相融合,进而建立左右图像对应点的判断依据并优化其编码长度。然后,构建基于十字交叉法与改进的引导滤波器相融合的聚合方法,从而实现视差值再分配,以降低误匹配率。最后,通过赢家通吃(Winner Take All,WTA)算法获取初始视差,并采用左右一致性检测方法及亚像素法提高匹配精度,从而获取最终的视差结果。实验结果表明,在Middlebury数据集的测试中,所提SAD-Census算法的平均非遮挡区域和全部区域的误匹配率为分别为2.67%和5.69%,测量200~900 mm距离的平均误差小于2%;而实际三维测量的最大误差为1.5%。实验结果检验了所提算法的有效性和可靠性。
机器视觉 立体匹配 SAD-Census变换 十字交叉法 引导滤波 machine vision stereo matching SAD-Census transform cross method guided filtering
Author Affiliations
Abstract
1 School of Medical Imaging, Xuzhou Medical University, Xuzhou 221004, China
2 School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116, China
In this work, the perovskite solar cells (PSCs) were fabricated with the bandgap-tunable (FA)x(MA)1-xPbI3 absorber layers through a facile two-stage deposition route. The doping was realized by adding the formamidinium iodide (FAI) into a precursor MAI solution. Both the surface morphology and electrochemical impedance spectra (EIS) were con-ducted to evaluate the absorber layers or solar cells. After the optimization, the best PSC performance of 14.73% was achieved at a nominal FAI content of 12.5 at.%. The performance enhancement was attributed to both the enhance-ment of visible light harvesting and carrier transport capability. Besides, the stability of a PSC device based on the single MAPbI3 absorber layer was also investigated, and a power conversion efficiency (PCE) of 11.27 % remained even after laying in vacuum for 10 days.
光电子快报(英文版)
2019, 15(2): 117
1 汕头大学 机械电子工程系, 广东 汕头 515063
2 华南理工大学 机械与汽车工程学院, 广州 510640
针对异形件曲面弧度的测量问题, 提出了一种基于单目视觉的曲面弧度测量方法.首先, 用基于三色LED环形光源和CCD彩色相机组成的单目视觉系统采集单张包含被测曲面表面特性的彩色图像; 其次, 分析该图像的彩色分布特征、灰度变化规律和相邻区域特征的相关性, 设计分割方法, 完成目标曲面的分割; 然后, 基于单目视觉系统成像模型, 结合材质与实验环境相关参量, 推导出被测表面高度计算方程; 最后, 解出相邻像素点间的高度累加分量, 进而还原被测点的高度, 在此基础上, 建立曲面弧度测量模型并完成曲面弧度测量.分别对3D打印曲面样品、螺钉螺纹、SIM卡槽进行了曲面弧度测量实验, 与激光三角法测量结果对比, 所提方法误差小于±3.6%, 测量准确度为0.000 1 rad, 曲面弧度测量时长小于0.6 s.实验结果表明, 该方法对测量物体边缘、高度突变, 高度渐变等类型的曲面都具有良好的适应性, 在实现较高准确度测量的同时, 具有较快的测量速度.
光学技术与仪器 曲面弧度测量 单目视觉 视觉测量 三维重建 Optical technology and instrument Curvature measurement of curved surface Monocular vision Visual measurement 3D reconstruction 光子学报
2018, 47(11): 1112002