地基RGB图像与多源卫星数据的甘蔗长势监测对比分析OA

To explore the applicability and optimal observation angle of ground-based RGB vegetation index in sugarcane growth monitoring,determine the ground observation angle with the highest matching degree with satellite NDVI,and evaluate the consistency between satellite data with different spatial resolutions(Sentinel-2,Landsat-8,MODIS)and ground-based monitoring results.In this study,the canopy RGB images of three sugarcane ecological observation stations in Fusui(0°horizontal photography),Laibin(45°oblique photography)and Liubei(90°vertical photography)were used as data sources to calculate 12 kinds of visible light vegetation indexes;Simultaneously acquire the NDVI of Sentinel-2(10 m),Landsat-8(30 m)and MODIS(250 m)satellites in the same period,and analyze the differences between ground-based and satellite monitoring through time series matching and linear fitting.The results showed that:①The 12 ground-based RGB vegetation indexes could effectively reflect the seasonal growth dynamics of sugarcane.The eight indices including GLA,VARI,MGRVI,RGBVI,NGRDI,VEG,ExG and ExGR showed seasonal changes that increased at first and then decreased,while CIVE,DGCI and EXR showed the opposite trend.In addition,NDYI showed a multi peak fluctuation and overall upward trend at Laibin station;②Under different shooting angles,ExGR and MODIS NDVI fitted best for 0°horizontal shooting(Fusui test station)(R2=0.804,p＜0.001),and RGBVI and Landsat-8 NDVI fitted best for 45°oblique shooting(Laibin test station)(R2=0.635,p＜0.001),while R2 of all indices and satellite NDVI for 90°vertical shooting(Liubei test station)except DGCI were lower than 0.300,and p values were mostly higher than 0.05,which was not suitable for collaborative monitoring.On the other hand,the correlation of NDYI in each observation station was low,so it was not suitable to be used as the core index of satellite verification;③The overall performance of Landsat-8(30 m)and MODIS(250 m)was better than Sentinel-2(10 m),and higher spatial resolution did not necessarily lead to higher goodness of fit.The results show that the ground-based RGB vegetation index can be effectively applied to sugarcane growth monitoring,and the fitting effect of ExGR,RGBVI,GLA and satellite NDVI was the best.The 90°vertical shooting angle was not suitable for sugarcane growth monitoring,and NDYI was not recommended for satellite verification.The consistency between Landsat-8 and MODIS and ground-based monitoring was better than Sentinel-2,indicating that higher spatial resolution may not bring better ground-based satellite synergy.