Yunhua Cao

Spectral scattering characteristics of space target in near-UV to visible bands

In this study, the spectral scattering characteristics of a space target are calculated in the near-UV to visible bands on the basis of measured data of spectral hemispheric reflectivity in the upper half space. Further, the bidirectional reflection distribution function (BRDF) model proposed by Davies is modified to describe the light scattering properties of a target surface. This modification aims to improve the characteristics identifying ability for different space targets. By using this modified Davies spectrum BRDF model, the spectral scattering characteristics of each subsurface can be obtained. A mathematical model of spectral scattering properties of the space target is built by summing all the contributing surface grid reflection scattering components, considering the impact of surface shadow effect.Moreover, the spectral scattering characteristics of the space target calculated with both the traditional and modified Davies BRDF models are compared. The results show that in the fixed and modified cases, the hemispheric reflectivity significantly affects the spectral scattering irradiance of the target.

Seven-parameter statistical model for BRDF in the UV band

A new semi-empirical seven-parameter BRDF model is developed in the UV band using experimentally measured data. The model is based on the five-parameter model of Wu and the fourteen-parameter model of Renhorn and Boreman. Surface scatter, bulk scatter and retro-reflection scatter are considered. An optimizing modeling method, the artificial immune network genetic algorithm, is used to fit the BRDF measurement data over a wide range of incident angles. The calculation time and accuracy of the five- and seven-parameter models are compared. After fixing the seven parameters, the model can well describe scattering data in the UV band.

Measurement of optical characteristics of solar panels used on satellite

An automatic measurement device is developed to measure Spectral Bidirectional Reflectance Distribution Function (BRDF) of various samples in the band from 400 to 2000 nm. Spectral BRDF of two kinds of solar panels (silicon solar panel and gallium arsenide solar panel) used on satellite is measured. Spectral Directional Hemisphere Reflectance (DHR) of the solar panels is measured in the band from 400 to 1800 nm. Measured data of the two kinds of solar panel exhibit a high specular reflection nature and a total hemisphere reflectance lower than 0.1 in the band from 400 to 1000 nm. Specular peaks of gallium arsenide solar panel are higher and narrower than those of silicon solar panel in the measured data of spectral BRDF. DHR of silicon solar panel increases to approximately 0.6 quickly at wavelength greater than 1000 nm. As to gallium arsenide solar panel, DHR remains below 0.3 in the band from 1000 to 1800 nm.

Study of infrared reflection characteristics of aerial target using MODIS data on GPU

To study of the infrared signature of an aerial target, it is required to precisely model the background radiation. Simple empirical models or standard atmospheric models in LOWTRAN/MODTRAN were used in earlier studies. To further precisely model the thermal radiation of earth’s surface and atmospheric radiance/transmittance, the atmospheric profile, land surface temperature, and emissivity, the sea surface temperature retrieved from moderate-resolution imaging spectroradiometer, and the sea surface emissivity model developed by Wu and Smith are utilized in this study. Meanwhile, considering that the reflection of background radiation incident from different directions in each spectral wavelength can be calculated in parallel, implementations using open multi-processing and compute unified device architecture on a multi-core CPU and many-core graphics processing unit (GPU) are presented and speedups of 9

The laser range profile and range imaging of a coarse cone

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Calculation method for laser radar cross sections of rotationally symmetric targets

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Measurement and analysis for scattering characteristics of flat plate with green camouflage paint

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