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The Design, Data Processing and Applications of Luojia 1-01 Satellite

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Remote Sensors".

Deadline for manuscript submissions: closed (30 June 2019) | Viewed by 77656

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Prof. Dr. Guo Zhang

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State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, China
Interests: design of optical SAR laser satellite; data processing and application of optical SAR laser satellite

Prof. Dr. Qiming Zhou

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Department of Geography and Centre for Geo-computation Studies, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
Interests: change detection and land cover modelling with remote sensing; digital terrain analysis and hydrological modeling; climate change and its impacts on water resources and ecosystems; arid zone studies
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Dr. Bailang Yu

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Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai, China
Interests: nighttime light remote sensing; urban remote sensing; object-oriented analysis for remotely sensed images; LiDaR (light detection and ranging)
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Prof. Dr. Xing Zhong

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Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, Jilin 130033, China
Interests: remote sensing optics; optical design and testing; space camera; small satellites

Special Issue Information

Dear Colleagues,

The Luojia 1-01 satellite is a small satellite that was designed and managed by Wuhan University. One of the most significant feature of the satellite is its ability to acquire low-orbit high-resolution night-time light imagery, which opens unprecedent opportunities for night-light image applications. The resolution of the satellite is 130 meters. Under ideal conditions, the national night light image can be completed within 15 days. All night light remote sensing data of Luojia1-01 are free from the high resolution data and application center of the Hubei data and application center(http://www.hbeos.org.cn/).

An open call for paper will be issued for, but not limited to, the following topics:

The mission status and planned and operational products
The satellite system design and manufacture
The calibration and validation activities of Luojia 1-01 and characteristics of onboard instruments
The status of collaborative ground segments (CGS)
Tools, toolboxes and algorithms for Luojia 1-01 data processing and analysis

Prof. Dr. Guo Zhang
Prof. Dr. Qiming Zhou
Prof. Dr. Bailang Yu
Prof. Dr. Xing Zhong
Guest Editors

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Keywords

Night-light imagery
Satellite system design
Luojia 1-01
Calibration and validation
Remote sensing applications

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Published Papers (12 papers)

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Research

16 pages, 6480 KiB

Open AccessArticle

Night-Light Image Restoration Method Based on Night Scattering Model for Luojia 1-01 Satellite

by Lijing Bu, Zhenghui Xu, Guo Zhang and Zhengpeng Zhang

Sensors 2019, 19(17), 3761; https://doi.org/10.3390/s19173761 - 30 Aug 2019

Cited by 10 | Viewed by 4103

Abstract

Aiming at solving the degradation problem of Luojia 1-01 night-light remote sensing images, the main reason for the “glow” phenomenon was analyzed. The APSF (Atmospheric Point Spread Function) template of night-light image was obtained from atmospheric source scattering. The template was used as the initial value in the regularization restoration model in this paper. Experiments were carried out using single point and regional images. The results demonstrate that the estimated APSF and restoration results of the method are better than those from other methods, and the image quality is improved after restoration. Full article

(This article belongs to the Special Issue The Design, Data Processing and Applications of Luojia 1-01 Satellite)

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16 pages, 6729 KiB

Open AccessArticle

Assessing the Ability of Luojia 1-01 Imagery to Detect Feeble Nighttime Lights

by Xue Li, Zhumei Liu, Xiaolin Chen and Jie Sun

Sensors 2019, 19(17), 3708; https://doi.org/10.3390/s19173708 - 26 Aug 2019

Cited by 28 | Viewed by 3637

Abstract

The Luojia1-01 (LJ1-01) satellite launched on 2 June 2018 provides a new option for nighttime light (NTL) application research. In this paper, four types of human settlements, such as cities, counties, towns and villages, are sampled to evaluate the potential of LJ1-01 to detect feeble NTL by comparing with the NTL images from the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS) and the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-Orbiting Partnership Satellite. First, the landscape indices and cutoff threshold method are applied to enhance signal-noise ratio (SNR). Then, the detection accuracy of samples is evaluated to determine the optimal cutoff threshold for each NTL data source. After that, the spatial correspondence of different NTL images and the area consistency between the samples and NTL footprints are compared. Finally, after the discussion of feeble NTL detection and the influence of clouds, moonlight and image composites, it can be concluded that LJ1-01 is more suitable for detection feeble NTL objects, while great importance should be attached to the measures to eliminate the noise in LJ1-01 image and make LJ1-01 more widely used: (1) In the study area, a suitable cutoff threshold of LJ1-01 image can be set to 0.1 nano-Wcm⁻²sr⁻¹, which is lower than that of VIIRS image (0.3 nano-Wcm⁻²sr⁻¹), and this enables LJ1-01 to reserve more information of NTL, especially the feeble NTL. Moreover, the minimum area that can be identified by NTL footprints from LJ1-01 is 0.02 km², while that of VIIRS and DMSP are 0.3 km² and 4.5 km², respectively. (2) The cutoff threshold method can identify the range of NTL with more noise, but cannot eliminate the noise separately. The filtering method and the image composition method may play more important role in the applications of LJ1-01 data. Full article

(This article belongs to the Special Issue The Design, Data Processing and Applications of Luojia 1-01 Satellite)

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20 pages, 18848 KiB

Open AccessArticle

Potentiality of Using Luojia1-01 Night-Time Light Imagery to Estimate Urban Community Housing Price—A Case Study in Wuhan, China

by Chang Li, Linqing Zou, Yijin Wu and Huimin Xu

Sensors 2019, 19(14), 3167; https://doi.org/10.3390/s19143167 - 18 Jul 2019

Cited by 22 | Viewed by 4136

Abstract

The first professional night-time light remote sensing satellite in China, Luojia1-01, has raised the resolution of night-time light data to 130 m, which provides a possibility for the study of small-scale night-time light. This paper is the first research on spatial analysis and quantitative modeling between night-time light intensity (NTLI) and community housing price (CHP) on a small scale by using the Luojia1-01 night-time light imagery. This paper takes Wuhan as the research area, CHP data obtained by web-crawler technology as the research object, combines Luojia1-01 data, and carries out spatial correlation analysis and quantitative modeling on a small scale for them. The experimental results show that there is a strong linear positive correlation between the NTLI and CHP based on geographically weighted regression (GWR), and the CHP data in Wuhan have obvious spatial non-stationarity. Moreover, the coupling mechanism between the NTLI and CHP is also revealed. We can conclude that there is potential for estimating the CHP by using Luojia1-01 night-time light imagery. Full article

(This article belongs to the Special Issue The Design, Data Processing and Applications of Luojia 1-01 Satellite)

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13 pages, 2241 KiB

Open AccessArticle

Evaluating the Potential of LJ1-01 Nighttime Light Data for Modeling Socio-Economic Parameters

by Guo Zhang, Xueyao Guo, Deren Li and Boyang Jiang

Sensors 2019, 19(6), 1465; https://doi.org/10.3390/s19061465 - 26 Mar 2019

Cited by 69 | Viewed by 6315

Abstract

The LJ1-01 satellite is the first dedicated nighttime light remote sensing satellite in the world and offers a higher spatial resolution than the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS) and the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor on the Suomi National Polar-orbiting Partnership (NPP) satellites of the United States. This study compared the LJ1-01 nighttime light data with NPP/VIIRS data in the context of modeling socio-economic parameters. In the eastern and central regions of China, 10 parameters from the four aspects of gross regional product (annual average population, electricity consumption, and area of land in use) were selected to build linear regression models. The results showed that the LJ1-01 nighttime light data offered better potential for modeling socio-economic parameters than the equivalent NPP/VIIRS data; the former can be an effective tool for establishing models for socio-economic parameters. There were significant positive correlations between the two types of nighttime light data and the 10 socio-economic parameters; that for the gross regional product was the highest. Full article

(This article belongs to the Special Issue The Design, Data Processing and Applications of Luojia 1-01 Satellite)

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14 pages, 5394 KiB

Open AccessArticle

Analysis and Reduction of Solar Stray Light in the Nighttime Imaging Camera of Luojia-1 Satellite

by Xing Zhong, Zhiqiang Su, Guo Zhang, Zhigang Chen, Yao Meng, Deren Li and Yong Liu

Sensors 2019, 19(5), 1130; https://doi.org/10.3390/s19051130 - 6 Mar 2019

Cited by 28 | Viewed by 6654

Abstract

As one of the experimental payloads on Luojia-1 satellite, the nighttime imaging camera works with a high sensitivity to acquire nighttime light on earth. Solar stray light is a fatal problem for optical satellite works in the polar orbit, even for nighttime scene imaging, resulting in image saturation and light signal detection failure. To solve this problem, an analysis of the range of solar incident angles was conducted firstly. Based on the result, a special-shaped baffle was designed to avoid direct sunlight incidence. Moreover, the capability of stray light elimination of the lens was enhanced by an order of magnitude via optimizing the internal structure. An evaluation of secondary scattering stray lights into the camera from surrounding parts was performed based on a real satellite model. The results showed that the stray light elimination reaches a 10⁻¹⁰ order, meeting design requirements. Utilizing on-orbit images, the ability of satellites in illuminated areas to obtain artificial lights in dawn-dusk area was verified, proving the effectiveness of the stray light elimination design. Full article

(This article belongs to the Special Issue The Design, Data Processing and Applications of Luojia 1-01 Satellite)

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12 pages, 3525 KiB

Open AccessArticle

Thermal Stability Optimization of the Luojia 1-01 Nighttime Light Remote-Sensing Camera’s Principal Distance

by Kun Zhang, Xing Zhong, Guo Zhang, Deren Li, Zhiqiang Su, Yao Meng and Yonghua Jiang

Sensors 2019, 19(5), 990; https://doi.org/10.3390/s19050990 - 26 Feb 2019

Cited by 3 | Viewed by 4784

Abstract

The instability of the principal distance of the nighttime light remote-sensing camera of the Luojia 1-01 satellite directly affects the geometric accuracy of images, consequently affecting the results of analysis of nighttime light remote-sensing data. Based on the theory of optical passive athermal design, a mathematical model of optical-passive athermal design for principal distance stabilization is established. Positive and negative lenses of different materials and the mechanical structures of different materials are matched to optimize the optical system. According to the index requirements of the Luojia 1-01 camera, an image-telecentric optical system was designed under the guidance of the established mathematical model. In the temperature range of −20 °C to +60 °C, the principal distance of the system changes from −0.01 μm to +0.28 μm. After on-orbit testing, the geometric accuracy of the designed nighttime light remote-sensing camera is better than 0.20 pixels and less than index requirement of 0.3 pixels, which indicating that the principal distance maintains good stability on-orbit and meets the application requirements of nighttime light remote sensing. Full article

(This article belongs to the Special Issue The Design, Data Processing and Applications of Luojia 1-01 Satellite)

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18 pages, 8990 KiB

Open AccessArticle

Quasi-All-Passive Thermal Control System Design and On-Orbit Validation of Luojia 1-01 Satellite

by Lin Yang, Qiang Li, Lin Kong, Song Gu and Lei Zhang

Sensors 2019, 19(4), 827; https://doi.org/10.3390/s19040827 - 17 Feb 2019

Cited by 11 | Viewed by 5694

Abstract

In order to resolve the large fluctuations in temperature range problem of Luojia 1-01 satellite caused by low heat inertia and poor thermal conductivity of structure, a quasi-all-passive thermal control system (TCS) design is presented under the conditions of limited resources including mass and power consumption. The effectiveness of the TCS design is verified by both ground thermal balanced test and related telemetry data of on-orbit performance. Firstly, according to the structural features and working modes of the satellite, isothermal design was implemented and the effectiveness was verified by thermal analysis using finite element method. Secondly, based on the results of the thermal analysis, thermal design was optimized and verified by the thermal balanced test. Finally, the thermal design was proved to be effective by temperature data acquired from telemetry data of on-orbit performance, and the thermal analysis model was improved and updated based on the results of thermal balanced test and temperature data of on-orbit performance. The on-orbit data indicates that temperature of optical camera stables at about 12 °C, temperature of battery stables at 19 °C, temperature of instruments inside and outside the satellite cabin is ranging from 10 °C to 25 °C. Temperature fluctuation range of optical camera is less than 2 °C when it is not imaging. Temperature fluctuation range of instruments not facing the sun is less than 4 °C. The data suggests that the temperature level of the satellite meets general design requirements, and the quasi-all-passive TCS design of the satellite is practicable. Full article

(This article belongs to the Special Issue The Design, Data Processing and Applications of Luojia 1-01 Satellite)

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15 pages, 8245 KiB

Open AccessArticle

High Sensitive Night-time Light Imaging Camera Design and In-orbit Test of Luojia1-01 Satellite

by Zhiqiang Su, Xing Zhong, Guo Zhang, Yanjie Li, Xiaojun He, Qiang Wang, Zongxi Wei, Chunling He and Deren Li

Sensors 2019, 19(4), 797; https://doi.org/10.3390/s19040797 - 15 Feb 2019

Cited by 16 | Viewed by 5427

Abstract

Luojia1-01 satellite is the first scientific experimental satellite applied for night-time light remote sensing data acquisition, and the payload is an optical camera with high sensitivity, high radiation measurement accuracy and stable elements of interior orientation. At the same time, a special shaped hood is designed, which significantly improved the ability of the camera to suppress stray light. Camera electronics adopts the integrated design of focal plane and imaging processing, which greatly reduces the volume and weight of the system. In this paper, the design of the optical camera is summarized, and the results of in-orbit imaging performance tests are analyzed. The results show that the dynamic modulation transfer function (MTF) of the camera is better than 0.17, and the SNR is better than 35 dB under the condition of 10 lx illuminance and 0.3 reflectivity and all indicators meet the design requirements. The data obtained have been widely applied in many fields such as the process of urbanization, light pollution analysis, marine fisheries detection and military. Full article

(This article belongs to the Special Issue The Design, Data Processing and Applications of Luojia 1-01 Satellite)

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23 pages, 11815 KiB

Open AccessArticle

On-Orbit Relative Radiometric Calibration of the Night-Time Sensor of the LuoJia1-01 Satellite

by Guo Zhang, Litao Li, Yonghua Jiang, Xin Shen and Deren Li

Sensors 2018, 18(12), 4225; https://doi.org/10.3390/s18124225 - 2 Dec 2018

Cited by 47 | Viewed by 6750

Abstract

The LuoJia1-01 satellite can acquire high-resolution, high-sensitivity nighttime light data for night remote sensing applications. LuoJia1-01 is equipped with a 4-megapixel CMOS sensor composed of 2048 × 2048 unique detectors that record weak nighttime light on Earth. Owing to minute variations in manufacturing and temporal degradation, each detector’s behavior varies when exposed to uniform radiance, resulting in noticeable detector-level errors in the acquired imagery. Radiometric calibration helps to eliminate these detector-level errors. For the nighttime sensor of LuoJia1-01, it is difficult to directly use the nighttime light data to calibrate the detector-level errors, because at night there is no large-area uniform light source. This paper reports an on-orbit radiometric calibration method that uses daytime data to estimate the relative calibration coefficients for each detector in the LuoJia1-01 nighttime sensor, and uses the calibrated data to correct nighttime data. The image sensor has a high dynamic range (HDR) mode, which is optimized for day/night imaging applications. An HDR image can be constructed using low- and high-gain HDR images captured in HDR mode. Hence, a day-to-night radiometric reference transfer model, which uses daytime uniform calibration to calibrate the detector non-uniformity of the nighttime sensor, is herein built for LuoJia1-01. Owing to the lack of calibration equipment on-board LuoJia1-01, the dark current of the nighttime sensor is calibrated by collecting no-light desert images at new moon. The results show that in HDR mode (1) the root mean square of mean for each detector in low-gain (high-gain) images is better than 0.04 (0.07) in digital number (DN) after dark current correction; (2) the DN relationship between low- and high-gain images conforms to the quadratic polynomial mode; (3) streaking metrics are better than 0.2% after relative calibration; and (4) the nighttime sensor has the same relative correction parameters at different exposure times for the same gain parameters. Full article

(This article belongs to the Special Issue The Design, Data Processing and Applications of Luojia 1-01 Satellite)

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20 pages, 3771 KiB

Open AccessArticle

Initial Assessment of the LEO Based Navigation Signal Augmentation System from Luojia-1A Satellite

by Lei Wang, Ruizhi Chen, Deren Li, Guo Zhang, Xin Shen, Baoguo Yu, Cailun Wu, Song Xie, Peng Zhang, Ming Li and Yuanjin Pan

Sensors 2018, 18(11), 3919; https://doi.org/10.3390/s18113919 - 14 Nov 2018

Cited by 70 | Viewed by 8005

Abstract

A low Earth orbiter (LEO)-based navigation signal augmentation system is considered as a complementary of current global navigation satellite systems (GNSS), which can accelerate precise positioning convergence, strengthen the signal power, and improve signal quality. Wuhan University is dedicated to LEO-based navigation signal augmentation research and launched one scientific experimental satellite named Luojia-1A. The satellite is capable of broadcasting dual-frequency band ranging signals over China. The initial performance of the Luojia-1A satellite navigation augmentation system is assessed in this study. The ground tests indicate that the phase noise of the oscillator is sufficiently low to support the intended applications. The field ranging tests achieve 2.6 m and 0.013 m ranging precision for the pseudorange and carrier phase measurements, respectively. The in-orbit test shows that the internal precision of the ephemeris is approximate 0.1 m and the clock stability is 3 × 10⁻¹⁰. The pseudorange and carrier phase measurement noise evaluated from the geometry-free combination is about 3.3 m and 1.8 cm. Overall, the Luojia-1A navigation augmentation system is capable of providing useable LEO navigation augmentation signals with the empirical user equivalent ranging error (UERE) no worse than 3.6 m, which can be integrated with existing GNSS to improve the real-time navigation performance. Full article

(This article belongs to the Special Issue The Design, Data Processing and Applications of Luojia 1-01 Satellite)

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18 pages, 19704 KiB

Open AccessArticle

Mapping Urban Extent Using Luojia 1-01 Nighttime Light Imagery

by Xi Li, Lixian Zhao, Deren Li and Huimin Xu

Sensors 2018, 18(11), 3665; https://doi.org/10.3390/s18113665 - 29 Oct 2018

Cited by 142 | Viewed by 8594

Abstract

Luojia 1-01 satellite, launched on 2 June 2018, provides a new data source of nighttime light at 130 m resolution and shows potential for mapping urban extent. In this paper, using Luojia 1-01 and VIIRS nighttime light imagery, we compared several methods for extracting urban areas, including Human Settlement Index (HSI), Simple Thresholding Segmentation (STS) and SVM supervised classification. According to the accuracy assessment, the HSI method using LJ1-01 data had the best performance in urban extent extraction, which presented the largest Kappa Coefficient value, 0.834, among all the results. For the urban areas extracted by VIIRS based HSI method, the largest Kappa Coefficient value was 0.772. In contrast, the largest Kappa Coefficient values obtained by STS method were 0.79 and 0.7512 respectively when using LJ1-01 and VIIRS data, while for SVM method the values were 0.7829 and 0.7486 when using Landsat-LJ and Landsat-VIIRS composite data respectively. The experimented results demonstrated that the utilization of nighttime light imagery can largely improve the accuracy of urban extent extraction and LJ1-01 data, with a higher resolution and more abundant spatial information, can lead to better identification results than its predecessors. Full article

(This article belongs to the Special Issue The Design, Data Processing and Applications of Luojia 1-01 Satellite)

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15 pages, 6160 KiB

Open AccessArticle

Potentiality of Using Luojia 1-01 Nighttime Light Imagery to Investigate Artificial Light Pollution

by Wei Jiang, Guojin He, Tengfei Long, Hongxiang Guo, Ranyu Yin, Wanchun Leng, Huichan Liu and Guizhou Wang

Sensors 2018, 18(9), 2900; https://doi.org/10.3390/s18092900 - 1 Sep 2018

Cited by 132 | Viewed by 9997

Abstract

The successful launch of Luojia 1-01 complements the existing nighttime light data with a high spatial resolution of 130 m. This paper is the first study to assess the potential of using Luojia 1-01 nighttime light imagery for investigating artificial light pollution. Eight Luojia 1-01 images were selected to conduct geometric correction. Then, the ability of Luojia 1-01 to detect artificial light pollution was assessed from three aspects, including the comparison between Luojia 1-01 and the Suomi National Polar-Orbiting Partnership Visible Infrared Imaging Radiometer Suite (NPP-VIIRS), the source of artificial light pollution and the patterns of urban light pollution. Moreover, the advantages and limitations of Luojia 1-01 were discussed. The results showed the following: (1) Luojia 1-01 can detect a higher dynamic range and capture the finer spatial details of artificial nighttime light. (2) The averages of the artificial light brightness were different between various land use types. The brightness of the artificial light pollution of airports, streets, and commercial services is high, while dark areas include farmland and rivers. (3) The light pollution patterns of four cities decreased away from the urban core and the total light pollution is highly related to the economic development. Our findings confirm that Luojia 1-01 can be effectively used to investigate artificial light pollution. Some limitations of Luojia 1-01, including its spectral range, radiometric calibration and the effects of clouds and moonlight, should be researched in future studies. Full article

(This article belongs to the Special Issue The Design, Data Processing and Applications of Luojia 1-01 Satellite)

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