基于光场相机层析法的颗粒三维位置测量  

Tomographic Three-dimensional Particle Position Measurement Based on Light Field Camera

作　　者：顾高霏 赵军 孔明 郭天太 王道档 GU Gao-fei;ZHAO Jun;KONG Ming;GUO Tian-tai;WANG Dao-dang(College of Metrology and Measurement Engineering,China Jiliang University,Hangzhou 310018,China)

机构地区：[1]中国计量大学计量测试工程学院,杭州310018

出　　处：《光子学报》2020年第8期145-154,共10页Acta Photonica Sinica

基　　金：国家重点研究发展计划(No.2017YFF0205501);国家自然科学基金(No.51874264)。

摘　　要：利用光场相机采集颗粒图像,改进层析反演算法,可以快速准确地获得颗粒三维空间位置.基于光场相机成像原理,建立光线正向追迹模型,在此基础上对图像非零像素发出的光线进行反向追迹,实现非零像素与空间体素之间的映射,构建层析法反演颗粒三维位置的模型.根据提出的降维求解MART算法权重矩阵方法,结合相似三角形原理提高颗粒深度位置的反演精度.依据高斯Blob模型,将强度最大的体素中心位置作为反演的颗粒三维位置.实验证明改进型MART算法明显减少了计算时间及所需内存,x轴坐标误差为±0.16 mm,y轴坐标误差为±0.18 mm,z轴坐标误差为±1.8 mm,满足精度要求,更加适用于对计算速度要求较高的场合,具有良好实际应用价值.A light field camera is used to collect particle images,and the tomographic inversion algorithm is improved to obtain the three-dimensional spatial position of particles faster and more accurately.Based on imaging principle of the light field camera,a forward tracing model of light emitted by particles is established.On the basis of this model,a tomographic inversion model is constructed to reversely trace rays emitted from non-zero pixels and realize the mapping between non-zero pixels and spatial voxels.A descending dimension method is proposed to calculate the weighting matrix.The depth accuracy of MART algorithm is improved by combined with the similar triangle principle.According to the Gaussian Blob model,center position of voxel with the strongest intensity is taken as the three-dimensional position of particles.Experiments indicate that the improved MART algorithm can significantly reduce calculation time and memory size while meeting the accuracy requirement.The x-axis coordinate error is±0.16 mm.The yaxis coordinate error is±0.18 mm.The z-axis coordinate error is±1.8 mm.It is more suitable for occasions that demand higher calculation speed and has better practical application value.

关 键 词：光场相机 光线追迹 层析反演 MART算法 颗粒定位 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]