An Operational Radiometric Correction Technique for Shadow Reduction in Multispectral UAV Imagery

This study focuses on the recovery of information from shadowed pixels in RGB or multispectral imagery sensed unmanned aerial vehicles (UAVs). The proposed technique is based concept that a property characterizing given surface its spectral reflectance, i.e., ratio between flux reflected by and radiant received surface, this usually similar under direct-plus-diffuse irradiance diffuse when Lambertian behavior can be assumed. Scene-dependent elements, such as trees, shrubs, man-made constructions, terrain relief, block part direct (usually sunbeams), which only receives irradiance. As consequence, surfaces comprising image created UAV remote sensor appear. Regardless whether analyzed means photointerpretation digital classification methods, objective to create land cover maps, it hard treat these areas coherent way terms receiving hypothesis present work relationship conditions non-shadowed determined following classical empirical line techniques for fulfilling treatment both kinds areas. novelty presented method relies simultaneous situ reflectance measurements characterized targets followed smoothing penumbra area. Once lab, firstly, we accurately detected combining two well-known detection areas: (1) using physical approach sun’s position model area covered imagery; (2) image-based histogram properties intensity image. In paper, benefits combined usage techniques. Secondly, applied fit twin set spectrally target sets. One was placed (non-shadowed targets), whereas second (with same characteristics) (shadowed targets). Assuming homologous each same, approximated incoming through an correction. all whole scene. Finally, filter transitions. allowed operational areas, very common high-resolution imagery.