Dynamic Monitoring Of Maize Growth Based On Unmanned Aerial Vehicle Remote Sensing

As a C4 crop,maize has many advantages,such as higher photosynthetic efficiency,higher yield improvement potential,stronger stress resistance and wider application field,and has been widely planted all over the world.Corn,a leading crop in China,plays an unparalleled role in food security.As one of the main producing areas of maize in China,the growth and development of maize in Huang-Huai-Hai area has been studied by agronomists all the time.and its growth has been the key content of corn monitoring.With the development of UAV remote sensing technology,more and more people begin to use it to monitor the growth and development of corn in real time.UAV remote sensing has become the research focus of monitoring the growth and development of corn and carrying out growth analysis.In this study,the high-definition digital image and the multi-spectral image are obtained by using a multi-rotor unmanned aerial vehicle with a high-definition digital camera and a multi-spectral camera,the DEM image and the vegetation index NDVI image are synthesized by the remote sensing data,the elevation of the corn population and the processing NDVI are extracted by the image information,the elevation data and the plant height data are normalized after the elevation data and the plant height data are normalized,The saturation NDVI was analyzed by introducing the parameters after the analysis of the correlation of NDVI and ground biomass.The possibility of using UAV single monitoring data to analyze the plant height difference of summer corn population and the performance of biomass in the image were discussed,and the feasibility of UAV monitoring summer corn plant height and biomass was obtained.The specific results of the study are as follows:TIn the corn population with plant height difference,the RGB and multispectral images were calculated by attitude correction,image splicing,point cloud generation and spatial reconstruction,and the DEM data of corn population and the elevation of each processed crown population were obtained.After normalization of crown elevation and artificial plant height,the correlation between UAV and artificial plant height under different varieties and sowing date treatment was obtained,and the feasibility of monitoring population plant height difference by using corn crown DEM data was clarified.The results show that the digital elevation information obtained by high definition RGB camera and multispectral imaging equipment can reflect the height difference of corn population.The monitoring accuracy of high definition RGB camera is higher than that of multispectral imaging equipment.However,under the ready-made image equipment and treatment methods,the monitoring accuracy of plant height is insufficient,so it is difficult to reflect the difference of small plant height of corn population.Different growth stages had great influence on the monitoring of corn plant height.The plant height of the population affected by exposed surface was seriously underestimated when the crown layer had not yet completely covered the surface or when the senescence leaves were withered and yellow and drooping in the later growth stage.In this study,the factors affecting the monitoring of corn plant height by UAV imaging equipment were analyzed,which provided a reference for the application of this method in field production.Based on unmanned aerial vehicle(UAV)multi-spectral image,by correcting the multi-spectral data and analyzing the changes of NDVI in two periods after registration,the relationship between the above-ground biomass data and the data of above-ground biomass was established.The results shew that the data changes with the growth period.Due to the rapid growth and development of summer maize,the rapid growth of leaves,the fast ridging on the ground and the rapid saturation time of NDVI,it is difficult to carry out the follow-up analysis.In order to improve the precision,after correlation between NDVI and biomass,the near infrared reflectivity ? NIR of the image was set up with a weighting coefficient a.It is found that when summer maize is highly saturated,the weighted coefficient a was introduced to make the correlation coefficient of NDVI and biomass higher.In order to provide the basis for improving the precision of biomass inversion by using NDVI.