Analysis and measurement of the stray light of the visible and near-infrared imaging spectrometer

2018 ◽  
Author(s):  
Chao Luo ◽  
Xinhua Chen ◽  
Zhicheng Zhao ◽  
Qiao Pan ◽  
Minxue Tang ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Stray Light ◽  
Near Infrared Imaging ◽  
Imaging Spectrometer

scholarly journals Photometric Normalization of Chang’e-4 Visible and Near-Infrared Imaging Spectrometer Datasets: A Combined Study of In-Situ and Laboratory Spectral Measurements

2020 ◽  
Vol 12 (19) ◽  
pp. 3211
Author(s):  
Xiaobin Qi ◽  
Zongcheng Ling ◽  
Jiang Zhang ◽  
Jian Chen ◽  
Haijun Cao ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Landing Site ◽  
Near Infrared Imaging ◽  
Imaging Spectrometer ◽  
Quantitative Mineralogy ◽  
Infrared Spectral ◽  
Phase Functions ◽  
Phase Angles

Until 29 May 2020, the Visible and Near-Infrared Imaging Spectrometer (VNIS) onboard the Yutu-2 Rover of the Chang’e-4 (CE-4) has acquired 96 high-resolution surface in-situ imaging spectra. These spectra were acquired under different illumination conditions, thus photometric normalization should be conducted to correct the introduced albedo differences before deriving the quantitative mineralogy for accurate geologic interpretations. In this study, a Lommel–Seeliger (LS) model and Hapke radiative transfer (Hapke) model were used and empirical phase functions of the LS model were derived. The values of these derived phase functions exhibit declining trends with the increase in phase angles and the opposition effect and phase reddening effect were observed. Then, we discovered from in-situ and laboratory measurements that the shadows caused by surface roughness have significant impacts on reflectance spectra and proper corrections were introduced. The validations of different phase functions showed that the maximum discrepancy at 1500 nm of spectra corrected by the LS model was less (~3.7%) than that by the Hapke model (~7.4%). This is the first time that empirical phase functions have been derived for a wavelength from 450 to 2395 nm using in-situ visible and near-infrared spectral datasets. Generally, photometrically normalized spectra exhibit smaller spectral slopes, lower FeO contents and larger optical maturity parameter (OMAT) than spectra without correction. In addition, the band centers of the 1 and 2 μm absorption features of spectra after photometric normalization exhibit a more concentrated distribution, indicating the compositional homogeneity of soils at the CE-4 landing site.

Visible and Near-infrared Imaging Spectrometer aboard Chinese Chang'E 3 Spacecraft

2015 ◽  
pp. 121-139 ◽  
Author(s):  
Jianyu Wang ◽  
Zhiping He ◽  
Rong Shu ◽  
Rui Xu ◽  
Kai Chen ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Near Infrared Imaging ◽  
Imaging Spectrometer

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

2021 ◽  
Vol 13 (12) ◽  
pp. 2359
Author(s):  
Jiafei Xu ◽  
Meizhu Wang ◽  
Rong Wang ◽  
Qi Feng ◽  
Honglei Lin ◽  
...  
Keyword(s):  
Lunar Surface ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Specular Reflection ◽  
In Situ Measurements ◽  
The Moon ◽  
Spectral Measurements ◽  
Near Infrared Imaging ◽  
Imaging Spectrometer

In-situ measurements of the spectral information on the lunar surface are of significance to study the geological evolution of the Moon. China’s Chang’E-4 (CE-4) Yutu-2 rover has conducted several in-situ spectral explorations on the Moon. The visible and near-infrared imaging spectrometer (VNIS) onboard the rover has acquired a series of in-situ spectra of the regolith at the landing site. In general, the mineralogical research of the lunar surface relies on the accuracy of the in-situ data. However, the spectral measurements of the Yutu-2 rover may be affected by shadows and stray illumination. In this study, we analyzed 106 CE-4 VNIS spectra acquired in the first 24 lunar days of the mission and noted that six of these spectra were affected by the shadows of the rover. Therefore, a method was established to correct the effects of the rover shadow on the spectral measurements. After shadow correction, the FeO content in the affected area is corrected to 14.46 wt.%, which was similar to the result calculated in the normal regolith. Furthermore, according to the visible images, certain areas of the explored sites were noted to be unusually bright. Considering the reflectance, geometric information, and shining patterns of the multi-layer insulation (MLI), we examined the influence of the specular reflection of the MLI on the bright spot regionsd , and found that the five sets of data were likely not affected by the specular reflection of the MLI. The results indicated that the complex illumination considerably influences the in situ spectral data. This study can provide a basis to analyze the VNIS scientific data and help enhance the accuracy of interpretation of the composition at CE-4 landing sites.

Visible and Near-Infrared Imaging Spectrometer (VNIS) For Chang E-3

2014 ◽  
Author(s):  
Zhiping He ◽  
Binyong Wang ◽  
Gang Lv ◽  
Chunlai Li ◽  
Liyin Yuan ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Near Infrared Imaging ◽  
Imaging Spectrometer

scholarly journals IMPLEMENTATION STRATEGY OF VISIBLE AND NEAR-INFRARED IMAGING SPECTROMETER ON YUTU-2 ROVER BASED ON VISION MEASUREMENT TECHNOLOGY

2020 ◽  
Vol XLIII-B3-2020 ◽  
pp. 1191-1197
Author(s):  
T. Yu ◽  
Z. Liu ◽  
Z. Rong ◽  
Y. Wang ◽  
J. Wang ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Measurement Technology ◽  
The Moon ◽  
Near Infrared Imaging ◽  
Imaging Spectrometer ◽  
Precise Control ◽  
Vision Measurement ◽  
Communication Condition ◽  
Shortwave Infrared

Abstract. The Chang'e-4 successfully landed on the far side of the moon in January 2019. By the 12th lunar day, its Yutu-2 rover had achieved a breakthrough travel distance of greater than 300 m. A visible and near-infrared imaging spectrometer (VNIS), consisting of a visible and near-infrared (VNIR) imaging spectrometer and a shortwave infrared (SWIR) spectrometer was used for detecting mineralogical compositions of lunar-surface materials. Because VNIS is fixed on the front of the rover, and the field-of-view (FOV) of VNIR and SWIR are small (8.5° and 3.6° respectively), approaching and accurately pointing at the specific science target depend completely on the precise control of the moving rover.In this paper, a successful method of VNIS target detection based on vision measurement is proposed. First, the accurate position of the target is calculated via navigation camera imaging. Then, the moving path is planned by considering the terrain environment, illumination, communication condition, and other constraints. After the rover moves to the designed position, the binocular imaging of the hazard-avoidance cameras are activated, the detection direction and forward distance are calculated according to the images, and the FOV trajectory of the VINS is predicted while moving. Finally, by choosing the required moving control parameters, the imaging field of the VINS accurately cover the detected targets visually.These methods have been verified many times, and the results show that they are effective and feasible. The research results based on the VNIS data have successfully revealed the material composition on the far side of the moon and have deepened human understanding of its formation and evolution.

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