BACKGROUND REFLECTANCE COMPENSATION AND ITS EFFECT ON MULTISPECTRAL LEAF SURFACE MOISTURE ASSESSMENT

摘要

The feasibility of using a multispectral imaging sensor for non-contact leaf wetness sensing was evaluated. The changes of spectral reflectance in the visible (400-700 nm), very-near-infrared (700-1300 nm) and near-infrared ranges (1300-2500 nm) caused by leaf surface moisture were investigated under filtered tungsten halogen lighting. The spectral information collected using the imaging system was a mixture of the reflectance of the objects of interest and the background in the sensor's field of view. For accurate leaf surface water analysis, background compensation techniques were evaluated to obtain compensated reflectance spectra. Visible and near-infrared regions were found to be less affected by background and were well compensated, whereas very-near-infrared regions had large background effects. The background reflectance compensation significantly improved the accuracy of leaf surface water assessment. The study showed that the multispectral imaging technique could be used to assess coverage of high-volume spray applications