基于多光谱冠层成像仪的单株植物冠层体积及总面积指数测量误差分析

Error analysis of the measurement of canopy volume and PAI parameters for isolated tree canopy based on MCI method

基于多光谱冠层成像仪(MCI)测量方法,开展龙眼树冠层体积及总面积指数测量研究,以地面实测数据为基础,重点分析MCI外方位元素(测站三维坐标及三个姿态角)测量、测站距离及测量方案(测站距离、体元及影像分区大小参数组合)三大误差来源及其对测量精度影响.研究发现,测站外方位元素解算精度受控制点成像质量、分布方式、控制点数目等因素影响显著;当体元、影像分区大小固定时,冠层体积及PAI参数测量结果受测站距离、测量方案影响整体较小,且偏差范围均小于8%,但少量方案存在测量结果不稳定性现象,其体积及PAI测量偏差可高达15%.

In this paper, the canopy volume and plant area index parameters of an isolated Longan tree were measured based on MCI method. Destructive data were collected also and used to analyze and e-valuate the three main sources of errors of MCI method, such as the determination of exterior parame-ters of station, distance between station and tree, scheme of measurements etc. When the value of the size of the voxel and pixel zone was fixed, the estimation of canopy volume and PAI was affected not largely （the deviation usually below 8% ） by the measurement scheme and the distance between the station and tree. But the results of few cases showed a accidental deviation with a max value of 15%.