Impact of Varying Light and Dew on Ground Cover Estimates from Active NDVI,RGB,and LiDAR  

作　　者：David M.Deery David J.Smith Robert Davy Jose A.Jimenez-Berni Greg J.Rebetzke Richard A.James 

机构地区：[1]CSIRO Agriculture and Food,Canberra,ACT,Australia [2]CSIRO Agriculture and Food,Yanco,NSW,Australia [3]CSIRO Information Management and Technology,Canberra,ACT,Australia [4]Instituto Agricultura Sostenible,Consejo Superior de Investigaciones Cientificas,Cordoba,Spain

出　　处：《Plant Phenomics》2021年第1期263-276,共14页植物表型组学（英文）

基　　金：the findings of this study have been deposited in the CSIRO Data Access Portal(doi:10.25919/0xke-d287)。

摘　　要：Canopy ground cover(GC)is an important agronomic measure for evaluating crop establishment and early growth.This study evaluates the reliability of GC estimates,in the presence of varying light and dew on leaves,from three different ground-based sensors:(1)normalized difference vegetation index(NDVI)from the commercially available GreenSeeker®;(2)RGB images from a digital camera,where GC was determined as the portion of pixels from each image meeting a greenness criterion(i.e.,ðGreen−RedÞ/ðGreen+RedÞ>0);and(3)LiDAR using two separate approaches:(a)GC from LiDAR red reflectance(whereby red reflectance less than five was classified as vegetation)and(b)GC from LiDAR height(whereby height greater than 10 cm was classified as vegetation).Hourly measurements were made early in the season at two different growth stages(tillering and stem elongation),among wheat genotypes highly diverse for canopy characteristics.The active NDVI showed the least variation through time and was particularly stable,regardless of the available light or the presence of dew.In addition,between-sample-time Pearson correlations for NDVI were consistently high and significant(P<0:0001),ranging from 0.89 to 0.98.In comparison,GC from LiDAR and RGB showed greater variation across sampling times,and LiDAR red reflectance was strongly influenced by the presence of dew.Excluding times when the light was exceedingly low,correlations between GC from RGB and NDVI were consistently high(ranging from 0.79 to 0.92).The high reliability of the active NDVI sensor potentially affords a high degree of flexibility for users by enabling sampling across a broad range of acceptable light conditions.

关 键 词：LIDAR reflectance IMPACT 

分 类 号：Q94[生物学—植物学] TN95[电子电信—信号与信息处理]