End-to-end simulation model of rover-based hyperspectral remote-sensing systems: application to VNIS

Abstract

The simulation of remote-sensing hyperspectral images has various applications such as the design of future hyperspectral imaging systems, understanding of the image formation process, development and validation of data processing algorithms, and optimization of the instrument imaging mode. For incomplete understanding of the lunar surface and the wide environmental differences between earth and moon observation, imaging systems for lunar observation cannot be tested in their exact working environments before launch. In these cases, simulation of lunar hyperspectral images can be used as a powerful tool to analyse the imaging process on the moon. The VIS-NIR imaging spectrometer (VNIS) aboard the Chang'e-3 (CE-3) lunar rover is used to perform in situ mineral detection on the lunar surface, but the rover-based VNIS has some additional effects from the rover itself (e.g. the shadow caused by the rover). In this paper, a rover-based radiative transfer model has been developed, and the simulation model is able to generate realistic VNIS-like data in an automatic way under a set of user-driven instrument and illumination parameters. A realistic surface reflectance cube, as the original input for the simulation model, is provided by the interference imaging spectrometer (IIM) data of Chang'e-1 (CE-1). Several hyperspectral simulations in different illumination and observation geometries have been conducted to analyse the effects of shadow, specular irradiance, and diffuse irradiance on the imaging data. For certain illumination geometries, the simulation model can forecast image quality in different observation geometries; the model can also determine the optimal observation azimuth ranges at different solar elevation angles. Moreover, the simulation model can be used to provide test images for the rover effect elimination algorithms. These applications of the model can facilitate understanding by analysing the rover-based hyperspectral remote-sensing process and eventually obtaining highquality images of the lunar surface.

Effect of Lunar Complex Illumination on In Situ Measurements Obtained Using Visible and Near-Infrared Imaging Spectrometer of Chang’E-4

“…Notably, the multi-layer insulation (MLI) wrapped around the outside of the rover and lander and the rover's shadow likely affect the accuracy of the quantitative analysis based on the VNIS data. The results of ground simulation experiments performed under a specific solar altitude angle and different azimuth angles highlighted the effects of the shadow, specular reflection, and diffuse reflection on the imaging data [9]. Currently, researchers have focused on CE-3 VNIS data that in-situ detection can be constrained by the observation angles and surface roughness and unevenness, resulting in significant small-area shadow effects [10].…”

A Combined Quantitative Evaluation Model for the Capability of Hyperspectral Imagery for Mineral Mapping

“…In the simulation-based method, each pixel would be used as the research unit, and the pixel values can be obtained by simulation of the scene, the atmosphere, and the sensor. Here, simulated images are applied to classification or target detection, and then their application capability is evaluated [11,12]. These methods are applied to analyze the imaging performance of different scenes, but they are not combined with the application mission and do not consider the effects of processing algorithms.…”