Gölgelik Alanlarda Komşu Nesnelerin Işımaya Olan Etkisinin Gerçek Veriler ve Fiziksel Işıma Modeli Üzerinden İncelenmesi

Abstract

Highlights:Graphical/Tabular Abstract  Shadow detection from LiDAR and hyperspectral data  Conversion from radiance domain to reflectance domain based on the physical radiance model  Analysis of the reflection and radiance values in shadow areasTargets hidden in shadow areas are very difficult to detect from hyperspectral images. One way to mitigate this problem is to detect the shadow areas using light detection and ranging (LiDAR) sensors, and to correct for the hyperspectral data in these regions. For this purpose, this paper makes a detailed analysis of real data in shadow regions and compares it the data from open areas where there is no shadow present. Figure A. Shadow analysis using hyperspectral and LiDAR dataPurpose:In this study, the radiance and reflectance values of the shadow regions in hyperspectral data, and their relation to the sky-view factors in a physical model are investigated. With this work, our goal is to understand the physical phenomenon in hyperspectral images that occurs in shadow areas. Theory and Methods:First, shadow regions are found using LiDAR data and their radiance and reflectance values are plotted. Then, sky-view factors are obtained from LiDAR data. Third, using the Modtran software, sky radiance and sun irradiance values are obtained and the radiance values in the shadow region are examined. Lastly, the parameters obtained from the Modtran software as well as the data collected from shadow areas are used in the physical radiance model; and the reflectance values in shadowy areas are analyzed. Results:Path radiance, sky radiance and radiance from adjacent objects were analyzed from three datasets with shadow locations and from open areas where there is no shadow. The physical radiance model as well as the analysis of the real data confirmed that the photons reflected from the objects surronding the shadow region are more dominant than the sky-view factors. Conclusion:Upon investigating the reflectance and radiance values in comparison to the physical radiance model, it was found that the sky-view factors are not as dominant as the photons reflected from the objects surronding the shadow region.