高级检索+

田间茶树冠层三维信息获取及其高度和轮廓表达方法

Describing Height and Outline of Tea Canopy in Natural Field with 3D Sensing

  • 摘要: 茶树的冠层信息是茶树田间管理的重要内容,也是茶叶机械化作业机具设计的重要依据。针对传统的作物冠层信息获取方法费时费力、主观性强且易造成损伤等问题,提出了一种茶树冠层高度和轮廓的获取与估计方法。首先,通过3D LiDAR从多个站点采集茶园的点云数据,对原始点云进行姿态矫正、ROI划分、配准、降噪以及高程归一化预处理,得到高程归一化的茶树点云。其次,通过反距离权重插值法、不规则三角网插值法在不同空间分辨率下生成茶树的冠层高度模型(Canopy height model, CHM),其中,空间分辨率0.05 m下不规则三角网插值生成的茶树CHM具有较好的插值精度,模型产生的凹坑也相对较少。最后,分别以90~100间的21个百分位数提取CHM的栅格值作为茶树冠层高度与实测值比较,结果表明,第98.5百分位数时估计值最为准确,与真值间的相关系数为0.88,平均绝对误差为3.17 cm,均方根误差为4.16 cm。此外,在高程归一化的茶树点云中提取20处冠层断面点云,分别采用椭圆模型、高斯模型和二次多项式模型拟合了冠层轮廓点云,其中,二次多项式模型能更好地反映茶树冠层轮廓特征,点云与拟合曲线间平均最小距离的均值为2.60 cm,方差为0.21 cm2。研究可为茶园现代化管理和茶叶机械化作业机具的设计提供理论支持。

     

    Abstract: Canopy information is an important element of tea field management and an important basis for the design of related equipment. Aiming at the traditional methods of obtaining crop canopy information, which are time-consuming, subjective and prone to damage, a method of obtaining and estimating the height and outline of the tea tree canopy was proposed. Firstly, the point cloud data of the tea field was collected from multiple sites by 3D LiDAR, and the original point cloud was pre-processed with attitude correction, ROI selection, alignment, noise reduction, and elevation normalization to obtain the elevation-normalized tea tree point cloud. Secondly, the canopy height model(CHM) of tea trees was generated by inverse distance weight(IDW) and triangulation irregular network(TIN) at different spatial resolutions, among which, the CHM of tea trees generated by IDW at 0.05 m spatial resolution had better interpolation accuracy and the model produced relatively fewer pits. Finally, the raster values of CHM were extracted from 21 percentiles between 90 and 100 as the canopy height of tea trees and compared with the measured values. The results showed that the estimated value was most accurate when the percentile was 98.5, and the correlation coefficient with the true value was 0.88, with an average absolute error of 3.17 cm, and a root mean square error of 4.16 cm. In addition, totally 20 canopy section point clouds were extracted from the elevation-normalized tea tree point clouds and their outlines were fitted by elliptic, Gaussian and quadratic polynomial models, respectively. The results showed that the quadratic polynomial model could better reflect the characteristics of the tea tree canopy outline, and the mean value of the average minimum distance between the points and the fitted curves was 2.60 cm with a variance of 0.21 cm~2. The research can provide theoretical support for the modern management of tea fields and the design of related equipment.

     

/

返回文章
返回