A “Skylight” Simulator for HWIL Simulation of Hyperspectral Remote Sensing

Abstract

Even though digital simulation technology has been widely used in the last two decades, hardware-in-the-loop (HWIL) simulation is still an indispensable method for spectral uncertainty research of ground targets. However, previous facilities mainly focus on the simulation of panchromatic imaging. Therefore, neither the spectral nor the spatial performance is enough for hyperspectral simulation. To improve the accuracy of illumination simulation, a new dome-like skylight simulator is designed and developed to fit the spatial distribution and spectral characteristics of a real skylight for the wavelength from 350 nm to 2500 nm. The simulator's performance was tested using a spectroradiometer with different accessories. The spatial uniformity is greater than 0.91. The spectral mismatch decreases to 1/243 of the spectral mismatch of the Imagery Simulation Facility (ISF). The spatial distribution of radiance can be adjusted, and the accuracy of the adjustment is greater than 0.895. The ability of the skylight simulator is also demonstrated by comparing radiometric quantities measured in the skylight simulator with those in a real skylight in Beijing.

A Flight Direction Design Method for Airborne Spectral Imaging Considering the Anisotropy Reflectance of the Target in Rugged Terrain

“…So, the simulation scene was built with the BRF of simulated rock samples shown in Figure 6 according to the classification map [36], instead of simply using the airborne image. The classification map was developed according to the lithological and mineral distribution in the area [37]. The simulated rock samples were made by mixing mineral powders.…”

“…A physical simulation experiment was conducted to simulate the real imaging process one step further. As shown in Figure 10, a physically simulated scene under the illumination from a physical solar simulator and a physical skylight simulator [37] were imaged from several directions. As the rock sample in the Huangshan cooper mine was not enough for the scene simulation, the Huangshan Dong cooper mine was chosen as the experiment scene.…”