Reflection characteristics play a critical role in identifying, assessing, and responding to different types of oil spills. In this paper, we prepared three concentrations of oil-in-water (OW) emulsions and measured their directional reflection properties in the visible and near-IR range. The spectral differences in reflectance between OW emulsions and oil films were analyzed. Furthermore, the AVIRIS and Landsat 7 images collected over the oil spill accident in the Gulf of Mexico were used to demonstrate the feasibility to apply the experimental results in the identification of oil spill types. The results show that OW emulsions and oil films can be well discriminated in remote sensing images based on their reflectance spectral differences. The OW emulsion is mainly distributed in strips along the edge of the oil film, which is useful to delineate the spill outline and calculate the polluted area.
The directional reflection characteristics of fabrics with various texture structures is an important and challenging topic in computer graphics and visual simulation. In the present study, the Bidirectional Reflectance Distribution Function (BRDF) of four different textured fabrics is measured via a self-designed Scatterometry to analyze the effect of surface textures and illuminated wavelengths. Furthermore, a fast and simple BRDF model is provided, and optimal model parameters for fabric BRDF calculation were obtained via a genetic algorithm. The results indicate that the reflected distribution of fabrics is dominated by diffuse reflection and is modulated by surface textures and irradiated wavelengths.
The directional reflection characteristics of anisotropic surfaces play an important role in the precise modeling of radiative heat transfer and target detection. Nevertheless, the directional reflection characteristics of anisotropic machined surfaces have not been fully understood. In this work, an accurate automated scatterometer was built to investigate the bidirectional reflectance distribution function (BRDF) of anisotropic machined surfaces produced by various kinds of machining methods, including plain milling, planer processing, and flat grinding. The effects of the incident angle, machining method, and surface roughness on the bidirectional reflectance properties were studied. The results indicate that the incident azimuthal angle affects the BRDF of a plain-milling surface in a vitally different way compared to planer processing and flat grinding. When the plane of incidence orients parallel to the macroscopic surface strips, the plain-milling surface displays diffuse dominated reflection (reflected energy distributed over 90°), whereas the other two show mirror-like properties, only distributed about 4° around the specular direction. Under the same surface roughness, the plain-milling surface shows the weakest reflected intensity, while the flat-grinding surface has the strongest.
