利用多时序激光点云数据提取棉花表型参数方法

当前，能够实现作物表型参数高效、准确的测量和作物生育期表型参数的动态量化研究是表型研究和育种中亟待解决的问题之一。本研究以棉花为研究对象，采用三维激光扫描LiDAR技术获取棉花植株的多时序点云数据，针对棉花植株主干的几何特性，利用随机抽样一致算法（RANSAC）结合直线模型完成主干提取，并对剩余的点云进行区域增长聚类，实现各叶片的分割；在此基础上，完成植株体积、株高、叶长、叶宽等性状参数的估计。针对多时序棉花激光点云数据，采用匈牙利算法完成相邻时序作物点云数据的对齐、叶片器官对应关系的建立。同时，对各植株表型参数动态变化过程进行了量化。本研究针对3株棉花的4个生长点的点云数据，分别完成了主干提取、叶片分割，以及表型参数测量和动态量化。试验结果表明，本研究所采用的主干提取及叶片分割方法能够实现棉花的枝干和叶片分割。提取的株高、叶长、叶宽等表型参数与人工测量值的决定系数均趋近于1.0；同时，本研究实现了棉花表型参数的动态量化过程，为三维表型技术的实现提供了一种有效的方法。

Cotton Phenotypic Trait Extraction Using Multi-Temporal Laser Point Clouds

To cope with the challenges posed by the rapid growth of world population and global environmental changes, scholars should employ genetic and phenotypic analyses to breed crop varieties with improved responses to limited resource environments and soil conditions to increase crop yield and quality. Therefore, the efficient, accurate, and non-destructive measurement of crop phenotypic traits, and the dynamic quantification of phenotypic traits are urgently needed for crop phenotypic research, and breeding as well as for modern agricultural development. In this study, cotton plants were taken as research objects, and the multi-temporal point cloud data of cotton plants were collected by using three-dimensional laser scanning technology. The multi-temporal point clouds of three cotton plants at four time points were collected. First, RANSAC algorithm was implemented for main stem extraction on the original point cloud data of cotton plants, then region growing based clustering was carried out for leaf segmentation. Plant height was estimated by calculating the end points of the segmented main stem. Leaf length and width measurements were conducted on the segmented leaf parts. In addition, the volume was also estimated through the convex hull of the original point cloud of plant cotton. Then, multi-temporal point clouds of plants were registered, and organ correspondence was constructed with the Hungarian method. Finally, dynamic quantification of phenotypic traits including plant volume, plant height, leaf length, leaf width, and leaf area were calculated and analyzed. The overall performance of the approaches achieved a matching rate through a series of experiments, and the traits extracted by using of point cloud showed high correlation with the manually measured ones. The relative error between plant height and manual measurement results did not exceed 1.0%. The estimated leaf length and width on point clouds were highly correlated with the manually measured ones, and the coefficient of determination was nearly 1.0. The proposed 3D phenotyping methodology can be introduced and used to other crops for phenotyping.