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Prof. Kaichang Di
State Key Laboratory of Remote Sensing Science, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100101, China

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Research Keywords & Expertise

0 planetary mapping
0 Comparative planetology
0 Planetary remote sensing
0 Planetary rover localization and navigation
0 Planetary geomorphology

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Journal article
Published: 28 July 2021 in Remote Sensing
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Topographic products are important for mission operations and scientific research in lunar exploration. In a lunar rover mission, high-resolution digital elevation models are typically generated at waypoints by photogrammetry methods based on rover stereo images acquired by stereo cameras. In case stereo images are not available, the stereo-photogrammetric method will not be applicable. Alternatively, photometric stereo method can recover topographic information with pixel-level resolution from three or more images, which are acquired by one camera under the same viewing geometry with different illumination conditions. In this research, we extend the concept of photometric stereo to photogrammetric-photometric stereo by incorporating collinearity equations into imaging irradiance model. The proposed photogrammetric-photometric stereo algorithm for surface construction involves three steps. First, the terrain normal vector in object space is derived from collinearity equations, and image irradiance equation for close-range topographic mapping is determined. Second, based on image irradiance equations of multiple images, the height gradients in image space can be solved. Finally, the height map is reconstructed through global least-squares surface reconstruction with spectral regularization. Experiments were carried out using simulated lunar rover images and actual lunar rover images acquired by Yutu-2 rover of Chang’e-4 mission. The results indicate that the proposed method achieves high-resolution and high-precision surface reconstruction, and outperforms the traditional photometric stereo methods. The proposed method is valuable for ground-based lunar surface reconstruction and can be applicable to surface reconstruction of Earth and other planets.

ACS Style

Man Peng; Kaichang Di; Yexin Wang; Wenhui Wan; Zhaoqin Liu; Jia Wang; Lichun Li. A Photogrammetric-Photometric Stereo Method for High-Resolution Lunar Topographic Mapping Using Yutu-2 Rover Images. Remote Sensing 2021, 13, 2975 .

AMA Style

Man Peng, Kaichang Di, Yexin Wang, Wenhui Wan, Zhaoqin Liu, Jia Wang, Lichun Li. A Photogrammetric-Photometric Stereo Method for High-Resolution Lunar Topographic Mapping Using Yutu-2 Rover Images. Remote Sensing. 2021; 13 (15):2975.

Chicago/Turabian Style

Man Peng; Kaichang Di; Yexin Wang; Wenhui Wan; Zhaoqin Liu; Jia Wang; Lichun Li. 2021. "A Photogrammetric-Photometric Stereo Method for High-Resolution Lunar Topographic Mapping Using Yutu-2 Rover Images." Remote Sensing 13, no. 15: 2975.

Journal article
Published: 30 March 2021 in Remote Sensing
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The age of Mars yardangs is significant in studying their development and the evolution of paleoclimate conditions. For planetary surface or landforms, a common method for dating is based on the frequency and size distribution of all the superposed craters after they are formed. However, there is usually a long duration for the yardangs’ formation, and they will alter the superposed craters, making it impossible to give a reliable dating result with the method. An indirect method by analyzing the ages of the superposed layered ejecta was devised in the research. First, the layered ejecta that are superposed on and not altered by the yardangs are identified and mapped. Then, the ages of the layered ejecta are derived according to the crater frequency and size distribution on them. These ages indicate that the yardangs ceased development by these times, and the ages are valuable for studying the evolution of the yardangs. This indirect dating method was applied to the areas of Martian yardangs in the Medusae Fossae Formation (MFF). The ages of the selected six layered ejecta range from ~0.50 Ga to ~1.5 Ga, indicating that the evolution of the corresponding yardangs had been ceased before these times. Analysis of more layered ejecta craters and superposed yardangs implies that yardangs in the MFF have a long history of development and some yardangs are still in active development.

ACS Style

Jia Liu; Zongyu Yue; Kaichang Di; Sheng Gou; Shengli Niu. A Study about the Temporal Constraints on the Martian Yardangs’ Development in Medusae Fossae Formation. Remote Sensing 2021, 13, 1316 .

AMA Style

Jia Liu, Zongyu Yue, Kaichang Di, Sheng Gou, Shengli Niu. A Study about the Temporal Constraints on the Martian Yardangs’ Development in Medusae Fossae Formation. Remote Sensing. 2021; 13 (7):1316.

Chicago/Turabian Style

Jia Liu; Zongyu Yue; Kaichang Di; Sheng Gou; Shengli Niu. 2021. "A Study about the Temporal Constraints on the Martian Yardangs’ Development in Medusae Fossae Formation." Remote Sensing 13, no. 7: 1316.

Journal article
Published: 09 March 2021 in Journal of Geophysical Research: Planets
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During the exploration traverse of the Von Kármán crater on the lunar farside, the Yutu‐2 rover, part of China's Chang'e‐4 mission, come across rock fragments with higher albedo than the surrounding surface. This study investigates their origin, emplacement, and composition based on in situ spectral analysis and geological considerations. The spectral signatures of two fragments show a clear dominance of low‐calcium pyroxenes against the high‐calcium phases characteristic of the basalts infilling the Von Kármán crater. Based on spectral considerations, this suggests an allochthonous origin for the ejecta fragments, with the most likely source attributable to the Imbrian 73‐km Finsen crater. We propose that these rock fragments might have had a convoluted history, born as ejected target materials from the Imbrian Finsen impact, possibly buried and resurfaced several times within Von Kármán by the churning mechanisms that continuously reshape the lunar surface, and finally exhumed by a secondary impact from the Copernican 3.8‐km Zhinyu crater.

ACS Style

Sheng Gou; Zongyu Yue; Kaichang Di; Roberto Bugiolacchi; Wenhui Wan; Meiping Yang; Lejia Ye. Geologically Old but Freshly Exposed Rock Fragments Encountered by Yutu‐2 Rover. Journal of Geophysical Research: Planets 2021, 126, 1 .

AMA Style

Sheng Gou, Zongyu Yue, Kaichang Di, Roberto Bugiolacchi, Wenhui Wan, Meiping Yang, Lejia Ye. Geologically Old but Freshly Exposed Rock Fragments Encountered by Yutu‐2 Rover. Journal of Geophysical Research: Planets. 2021; 126 (3):1.

Chicago/Turabian Style

Sheng Gou; Zongyu Yue; Kaichang Di; Roberto Bugiolacchi; Wenhui Wan; Meiping Yang; Lejia Ye. 2021. "Geologically Old but Freshly Exposed Rock Fragments Encountered by Yutu‐2 Rover." Journal of Geophysical Research: Planets 126, no. 3: 1.

Journal article
Published: 14 February 2021 in Icarus
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Von Kármán crater's floor was flooded with mare basalts during the Imbrian period. This site is the target of China's ongoing Chang'e-4 mission that includes the Yutu-2 rover and its instrumental payload. The Zhinyu crater, one of the largest craters within a few tens of kilometers from the landing site, is the product of a fresh impact that excavated subsurface, basaltic materials onto the surface. The compositional characteristics of the continuous ejecta around the crater vary radially with distance, suggesting possible mineral heterogeneity at depth. At least three main mare flooding phases could have occurred within Von Kármán, producing a basalt layer of at least 320 m in thickness. However, a broadly consistent olivine composition (Fo#: 55) of the three proposed basalt layers suggests that the sources of the mare basalts would have been similar in composition, perhaps even consisting of a single magma chamber where magma had time to evolve. The Yutu-2 rover that is edging its way westwards, could in principle test this hypothesis, thus further constraining the thermal history of the Von Kármán crater.

ACS Style

Sheng Gou; Zongyu Yue; Kaichang Di; Roberto Bugiolacchi; Meng-Hua Zhu; Patrick C. Pinet; ZhanChuan Cai. Mare basalt flooding events surrounding Chang'e-4 landing site as revealed by Zhinyu crater ejecta. Icarus 2021, 360, 114370 .

AMA Style

Sheng Gou, Zongyu Yue, Kaichang Di, Roberto Bugiolacchi, Meng-Hua Zhu, Patrick C. Pinet, ZhanChuan Cai. Mare basalt flooding events surrounding Chang'e-4 landing site as revealed by Zhinyu crater ejecta. Icarus. 2021; 360 ():114370.

Chicago/Turabian Style

Sheng Gou; Zongyu Yue; Kaichang Di; Roberto Bugiolacchi; Meng-Hua Zhu; Patrick C. Pinet; ZhanChuan Cai. 2021. "Mare basalt flooding events surrounding Chang'e-4 landing site as revealed by Zhinyu crater ejecta." Icarus 360, no. : 114370.

Technical note
Published: 07 February 2021 in Remote Sensing
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Chang’e-5, China’s first unmanned lunar sample-return mission, was successfully landed in Northern Oceanus Procellarum on 1 December 2020. Determining the lander location precisely and timely is critical for both engineering operations and subsequent scientific research. Localization of the lander was performed using radio-tracking and image-based methods. The lander location was determined to be (51.92° W, 43.06° N) by both methods. Other localization results were compared for cross-validation. The localization results greatly contributed to the planning of the ascender lifting off from the lander and subsequent maneuvers, and they will contribute to scientific analysis of the returned samples and in situ acquired data.

ACS Style

Jia Wang; Yu Zhang; Kaichang Di; Ming Chen; Jianfeng Duan; Jing Kong; Jianfeng Xie; Zhaoqin Liu; Wenhui Wan; Zhifei Rong; Bin Liu; Man Peng; Yexin Wang. Localization of the Chang’e-5 Lander Using Radio-Tracking and Image-Based Methods. Remote Sensing 2021, 13, 590 .

AMA Style

Jia Wang, Yu Zhang, Kaichang Di, Ming Chen, Jianfeng Duan, Jing Kong, Jianfeng Xie, Zhaoqin Liu, Wenhui Wan, Zhifei Rong, Bin Liu, Man Peng, Yexin Wang. Localization of the Chang’e-5 Lander Using Radio-Tracking and Image-Based Methods. Remote Sensing. 2021; 13 (4):590.

Chicago/Turabian Style

Jia Wang; Yu Zhang; Kaichang Di; Ming Chen; Jianfeng Duan; Jing Kong; Jianfeng Xie; Zhaoqin Liu; Wenhui Wan; Zhifei Rong; Bin Liu; Man Peng; Yexin Wang. 2021. "Localization of the Chang’e-5 Lander Using Radio-Tracking and Image-Based Methods." Remote Sensing 13, no. 4: 590.

Journal article
Published: 06 July 2020 in Planetary and Space Science
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Mars yardang fields were globally mapped using the Thermal Emission Imaging System (THEMIS) global IR mosaic through visual interpretation and manual digitization. We classified the Martian yardangs into three types according to their shapes: long ridge, inverted hull and curvilinear shapes, and found that the number of long ridge yardang fields account for 88% of all 242 yardang fields. The global mapping results show that Martian Yardangs mainly distribute within 30°N-30°S and in topography of −49 m to −3742 m; the total area of yardang fields is about 411,460 km2, within which the area of the Medusae Fossae Formation (MFF) yardangs is about 262,700 km2. We identified and digitized individual yardang bodies wider than 500 m in the THEMIS mosaic and confirmed the boundaries after the Context Camera (CTX) image mosaic becoming available recently. The resultant 466 yardang bodies are subsequently used as samples for statistical analysis of the morphometric parameters. Among all of the orientations, N–S is the dominant orientation of the yardang samples, and the average length and width are 5626 m and 993 m respectively. The length to width ratios vary from 1.2:1 to 46.9:1 globally and vary from 1.5:1 to 46.9:1 in the most studied MFF. The mapping and statistical results provide important information about the global distribution of Mars yardangs and their morphological characteristics, which will be valuable to further study of the formation and evolution of Mars yardangs, and the aeolian environment.

ACS Style

Jia Liu; Kaichang Di; Sheng Gou; Zongyu Yue; Bin Liu; Jing Xiao; Zhaoqin Liu. Mapping and spatial statistical analysis of Mars Yardangs. Planetary and Space Science 2020, 192, 105035 .

AMA Style

Jia Liu, Kaichang Di, Sheng Gou, Zongyu Yue, Bin Liu, Jing Xiao, Zhaoqin Liu. Mapping and spatial statistical analysis of Mars Yardangs. Planetary and Space Science. 2020; 192 ():105035.

Chicago/Turabian Style

Jia Liu; Kaichang Di; Sheng Gou; Zongyu Yue; Bin Liu; Jing Xiao; Zhaoqin Liu. 2020. "Mapping and spatial statistical analysis of Mars Yardangs." Planetary and Space Science 192, no. : 105035.

Short communication
Published: 08 June 2020 in Earth and Planetary Science Letters
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Chang'e-4 rover discovered a dark greenish and glistening impact melt breccia in a crater during its traverse on the floor of Von Kármán crater within the South Pole Aitken (SPA) basin on the lunar farside. The discovered breccia, being 52 × 16 cm, resembles the lunar impact melt breccia samples 15466 and 70019 that returned by the Apollo missions. It was formed by impact-generated welding, cementing and agglutinating of lunar regolith and breccia. Clods surrounds the breccia-hosting crater were crushed into regolith powders by the rover's wheels, indicating the regolith may be compacted slightly and becomes blocky and friable. Relative mineral fractions are estimated from the in situ measured spectra by a Hapke model-based unmixing algorithm. Unmixing reveals that plagioclase (PLG, 45 ± 6%) is dominant in the regolith, followed by almost equal fractions of pyroxene (PYX, 7 ± 1%) and olivine (OL, 6 ± 2%), indicating the regolith is likely related to noritic rocks. The regolith measured by Chang'e-4 rover was actually a highly mixture of multiple sources, with ejecta from Finsen crater being primary and possible contributions from Alder crater. Finsen and Alder craters are on the margin of the proposed impact melt pool produced by the SPA basin-forming event. Therefore, the ultimate source of the regolith might originate from a differentiated melt pool or from a suite of igneous rocks.

ACS Style

Sheng Gou; Zongyu Yue; Kaichang Di; Jia Wang; Wenhui Wan; Zhaoqin Liu; Bin Liu; Man Peng; Yexin Wang; Zhiping He; Rui Xu. Impact melt breccia and surrounding regolith measured by Chang'e-4 rover. Earth and Planetary Science Letters 2020, 544, 116378 .

AMA Style

Sheng Gou, Zongyu Yue, Kaichang Di, Jia Wang, Wenhui Wan, Zhaoqin Liu, Bin Liu, Man Peng, Yexin Wang, Zhiping He, Rui Xu. Impact melt breccia and surrounding regolith measured by Chang'e-4 rover. Earth and Planetary Science Letters. 2020; 544 ():116378.

Chicago/Turabian Style

Sheng Gou; Zongyu Yue; Kaichang Di; Jia Wang; Wenhui Wan; Zhaoqin Liu; Bin Liu; Man Peng; Yexin Wang; Zhiping He; Rui Xu. 2020. "Impact melt breccia and surrounding regolith measured by Chang'e-4 rover." Earth and Planetary Science Letters 544, no. : 116378.

Short communication
Published: 23 April 2020 in Earth and Planetary Science Letters
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Chang'e-5 (CE-5) is the first sample-return mission of China's lunar exploration and will be launched in 2020. The planned landing area is near Mons Rümker in Oceanus Procellarum. It is important to have a detailed geological analysis of the landing area prior to the lunar sample collection. The crater size-frequency distribution curve, combined with radioisotope dating of components of the returned sample by CE-5, may allow a refinement of the lunar chronology function. Based on a digital orthophoto map with a pixel size of 1.5 m generated from more than 700 Lunar Reconnaissance Orbiter Camera Narrow Angle Camera images of the CE-5 landing area, all impact craters larger than 200 m in diameter were extracted. Using the resultant crater catalogue of 32,277 craters, a systematic analysis of the landing area including the crater distribution, morphology characteristics, and geologic model ages is conducted. The results show that craters smaller than 1,000 m are denser in the east and the west parts of the region, while those larger than 1,000 m tend to be more concentrated in the central part, particularly within the range of 61.5°W–64.5°W. Within nine geologic units divided using the spectral characteristics, the geologic unit of Em1 (Eratosthenian-aged mare, Em) near the Mons Rümker is the youngest with a model age of 2.02−0.16+0.16 Ga. The three Rümker plateau (IR) units are the oldest parts of the landing area with the largest model age of 3.49−0.12+0.073 Ga. The crater catalogue and the surface model age analysis results can contribute to the CE-5 mission as well as further scientific research.

ACS Style

Mengna Jia; Zongyu Yue; Kaichang Di; Bin Liu; Jianzhong Liu; Gregory Michael. A catalogue of impact craters larger than 200 m and surface age analysis in the Chang'e-5 landing area. Earth and Planetary Science Letters 2020, 541, 116272 .

AMA Style

Mengna Jia, Zongyu Yue, Kaichang Di, Bin Liu, Jianzhong Liu, Gregory Michael. A catalogue of impact craters larger than 200 m and surface age analysis in the Chang'e-5 landing area. Earth and Planetary Science Letters. 2020; 541 ():116272.

Chicago/Turabian Style

Mengna Jia; Zongyu Yue; Kaichang Di; Bin Liu; Jianzhong Liu; Gregory Michael. 2020. "A catalogue of impact craters larger than 200 m and surface age analysis in the Chang'e-5 landing area." Earth and Planetary Science Letters 541, no. : 116272.

Research paper
Published: 09 March 2020 in Science China Information Sciences
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This paper presents the techniques and results of landing-site topographic mapping and rover localization using orbital, descent and rover images in the Chang’e-4 mission. High-resolution maps of the landing site are generated from orbital and descent images. Local digital elevation models and digital orthophoto maps with 0.02 m resolution are generated at each waypoint. The location of the lander is determined as (177.588° E, 45.457° S) using festure-matching techniques. The cross-site visual localization method is routinely used to localize the rover at each waypoint to reduce error accumulation from wheel slippage and IMU drift in dead reckoning. After the first five lunar days, the rover travels 186.66 m from the lander, according to the cross-site visual localization. The developed methods and results have been directly utilized to support the mission’s operations. The maps and localization information are also valuable for supporting multiple scientific explorations of the landing site.

ACS Style

Zhaoqin Liu; Kaichang Di; Jian Li; Jianfeng Xie; Xiaofeng Cui; Luhua Xi; Wenhui Wan; Man Peng; Bin Liu; Yexin Wang; Sheng Gou; Zongyu Yue; Tianyi Yu; Lichun Li; Jia Wang; Chuankai Liu; Xin Xin; Mengna Jia; Zheng Bo; Jia Liu; Runzhi Wang; Shengli Niu; Kuan Zhang; Yi You; Jiangang Liu. Landing site topographic mapping and rover localization for Chang’e-4 mission. Science China Information Sciences 2020, 63, 1 -12.

AMA Style

Zhaoqin Liu, Kaichang Di, Jian Li, Jianfeng Xie, Xiaofeng Cui, Luhua Xi, Wenhui Wan, Man Peng, Bin Liu, Yexin Wang, Sheng Gou, Zongyu Yue, Tianyi Yu, Lichun Li, Jia Wang, Chuankai Liu, Xin Xin, Mengna Jia, Zheng Bo, Jia Liu, Runzhi Wang, Shengli Niu, Kuan Zhang, Yi You, Jiangang Liu. Landing site topographic mapping and rover localization for Chang’e-4 mission. Science China Information Sciences. 2020; 63 (4):1-12.

Chicago/Turabian Style

Zhaoqin Liu; Kaichang Di; Jian Li; Jianfeng Xie; Xiaofeng Cui; Luhua Xi; Wenhui Wan; Man Peng; Bin Liu; Yexin Wang; Sheng Gou; Zongyu Yue; Tianyi Yu; Lichun Li; Jia Wang; Chuankai Liu; Xin Xin; Mengna Jia; Zheng Bo; Jia Liu; Runzhi Wang; Shengli Niu; Kuan Zhang; Yi You; Jiangang Liu. 2020. "Landing site topographic mapping and rover localization for Chang’e-4 mission." Science China Information Sciences 63, no. 4: 1-12.

Journal article
Published: 14 February 2020 in Remote Sensing
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In planetary rover missions, rover path planning is critical to ensure the safety and efficiency of the rover traverse and in situ explorations. In the Chang’e-4 (CE-4) mission, we have proposed and developed vision-based decision support methods comprising obstacle map generation and path evaluation for the rover. At each waypoint along the rover traverse, digital elevation model (DEM) is automatically generated, which is then used for obstacle map generation and path searching. For path evaluation, the searched path and the predicted wheel trajectories are projected onto the original images captured by different cameras to coincide with the real observation scenario. The proposed methods have been applied in the CE-4 mission to support teleoperation of the rover, and examples of multiple applications used in the mission are presented in this paper. Under the support of the proposed techniques, by the end of the 14th lunar day (3 February 2020), the rover has already travelled 367.25 meters on the far side of the Moon.

ACS Style

Yexin Wang; Wenhui Wan; Sheng Gou; Man Peng; Zhaoqin Liu; Kaichang Di; Lichun Li; Tianyi Yu; Jia Wang; Xiao Cheng. Vision-Based Decision Support for Rover Path Planning in the Chang’e-4 Mission. Remote Sensing 2020, 12, 624 .

AMA Style

Yexin Wang, Wenhui Wan, Sheng Gou, Man Peng, Zhaoqin Liu, Kaichang Di, Lichun Li, Tianyi Yu, Jia Wang, Xiao Cheng. Vision-Based Decision Support for Rover Path Planning in the Chang’e-4 Mission. Remote Sensing. 2020; 12 (4):624.

Chicago/Turabian Style

Yexin Wang; Wenhui Wan; Sheng Gou; Man Peng; Zhaoqin Liu; Kaichang Di; Lichun Li; Tianyi Yu; Jia Wang; Xiao Cheng. 2020. "Vision-Based Decision Support for Rover Path Planning in the Chang’e-4 Mission." Remote Sensing 12, no. 4: 624.

Journal article
Published: 06 February 2020 in Remote Sensing
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The Chang’E-2 digital elevation model (DEM, named CE2TMap2015), which is the highest resolution DEM product in China, was released with global coverage of the lunar surface. A detailed geometric quality assessment of the product is desirable for wider applications by users. A novel procedure for evaluating DEM geometric quality, which investigates both the global geometric uncertainty and local gross errors, is proposed in this paper. First, the DEM was divided into regular blocks and matched with the reference DEM. Then, the characteristics of errors were investigated using the statistical information of the matched tie points. Next, the local outlier factor (LOF) algorithm was performed to locate the gross errors. In our experiment, CE2TMap2015 was evaluated using the proposed method, with SLDEM2015 as the reference DEM. The results show that there were widespread geometric inconsistencies with an area-weighted average of 183.1 m horizontally (with the standard deviation being 101.2 m) and 2.3 m vertically (with the standard deviation being 15.4 m). Gross errors were detected automatically and were excluded in the statistical analysis. The periodic errors were extracted in the frequency domain using a Fourier transform. Our research results provide instructional information for the utilization of CE2TMap2015 by world-wide users. The proposed method can be used in the assessment of other planetary DEMs.

ACS Style

Xin Xin; Bin Liu; Kaichang Di; Zongyu Yue; Sheng Gou. Geometric Quality Assessment of Chang’E-2 Global DEM Product. Remote Sensing 2020, 12, 526 .

AMA Style

Xin Xin, Bin Liu, Kaichang Di, Zongyu Yue, Sheng Gou. Geometric Quality Assessment of Chang’E-2 Global DEM Product. Remote Sensing. 2020; 12 (3):526.

Chicago/Turabian Style

Xin Xin; Bin Liu; Kaichang Di; Zongyu Yue; Sheng Gou. 2020. "Geometric Quality Assessment of Chang’E-2 Global DEM Product." Remote Sensing 12, no. 3: 526.

Short communication
Published: 28 January 2020 in Earth and Planetary Science Letters
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Space weathering introduces confounding effects on visible and near infrared reflectance spectra of airless bodies, which considerably darkens the reflectance, reddens the continuum slope and suppresses absorption features. It's mainly attributed to the gradual formation and accumulation of submicroscopic metallic iron (SMFe) on regolith grains. In situ spectral measurements from Chang'e-4 rover provide a unique opportunity to investigate the space weathering effects on the intact lunar farside regolith. SMFe abundance at the landing site, which is 0.32±0.06 wt.%, is retrieved from in situ measured reflectance spectra by using Hapke model. The derived Is/FeO maturity index (82±15) indicates the Finsen crater ejecta-sourced regolith is mature, which is consistent with the geologic background that it had experienced about 3.7 Ga space weathering.

ACS Style

Sheng Gou; Zongyu Yue; Kaichang Di; Wenhui Wan; Zhaoqin Liu; Bin Liu; Man Peng; Yexin Wang; Zhiping He; Rui Xu. In situ spectral measurements of space weathering by Chang'e-4 rover. Earth and Planetary Science Letters 2020, 535, 116117 .

AMA Style

Sheng Gou, Zongyu Yue, Kaichang Di, Wenhui Wan, Zhaoqin Liu, Bin Liu, Man Peng, Yexin Wang, Zhiping He, Rui Xu. In situ spectral measurements of space weathering by Chang'e-4 rover. Earth and Planetary Science Letters. 2020; 535 ():116117.

Chicago/Turabian Style

Sheng Gou; Zongyu Yue; Kaichang Di; Wenhui Wan; Zhaoqin Liu; Bin Liu; Man Peng; Yexin Wang; Zhiping He; Rui Xu. 2020. "In situ spectral measurements of space weathering by Chang'e-4 rover." Earth and Planetary Science Letters 535, no. : 116117.

Articles
Published: 02 January 2020 in Geo-spatial Information Science
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This paper presents a brief overview of the geospatial technologies developed and applied in Chang’e-3 and Chang’e-4 lunar rover missions. Photogrammetric mapping techniques were used to produce topographic products of the landing site with meter level resolution using orbital images before landing, and to produce centimeter-resolution topographic products in near real-time after landing. Visual positioning techniques were used to determine the locations of the two landers using descent images and orbital basemaps immediately after landing. During surface operations, visual-positioning-based rover localization was performed routinely at each waypoint using Navcam images. The topographic analysis and rover localization results directly supported waypoint-to-waypoint path planning, science target selection and scientific investigations. A GIS-based digital cartography system was also developed to support rover teleoperation.

ACS Style

Kaichang Di; Zhaoqin Liu; Wenhui Wan; Man Peng; Bin Liu; Yexin Wang; Sheng Gou; Zongyu Yue. Geospatial technologies for Chang’e-3 and Chang’e-4 lunar rover missions. Geo-spatial Information Science 2020, 23, 87 -97.

AMA Style

Kaichang Di, Zhaoqin Liu, Wenhui Wan, Man Peng, Bin Liu, Yexin Wang, Sheng Gou, Zongyu Yue. Geospatial technologies for Chang’e-3 and Chang’e-4 lunar rover missions. Geo-spatial Information Science. 2020; 23 (1):87-97.

Chicago/Turabian Style

Kaichang Di; Zhaoqin Liu; Wenhui Wan; Man Peng; Bin Liu; Yexin Wang; Sheng Gou; Zongyu Yue. 2020. "Geospatial technologies for Chang’e-3 and Chang’e-4 lunar rover missions." Geo-spatial Information Science 23, no. 1: 87-97.

Research letter
Published: 22 November 2019 in Geophysical Research Letters
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Chang'e‐4 (CE‐4) achieved the first farside landing in Von Kármán crater. In the landing site, linear features have been identified previously from SLDEM and considered to be ejecta from the neighboring Finsen crater. The 5 cm grid spacing digital elevation model (DEM) of the landing site, generated from the rover's panoramic images, provides more details of the rugged terrain. We further interpret the superimposition of NE‐SW ejecta from Finsen crater on the underlying SE‐NW dome‐like surface relief from Alder crater. The landing site is ~70 m higher than the mare basalts within Von Kármán crater. Numerical simulations predict ~30 m and ~35 m ejecta deposited at the landing site from Finsen and Alder craters, respectively. The good agreement between the DEM data and ejecta predicted thickness reveals the topographic evolution of Von Kármán crater, indicating that the rover‐measured material is excavated from Finsen crater with possible contributions from Alder crater.

ACS Style

Kaichang Di; Meng‐Hua Zhu; Zongyu Yue; Yangting Lin; Wenhui Wan; Zhaoqin Liu; Sheng Gou; Bin Liu; Man Peng; Yexin Wang; Shengli Niu; Jinhai Zhang; Jian Li; Jianfeng Xie; Luhua Xi; Jianfeng Yang; Bin Xue. Topographic Evolution of Von Kármán Crater Revealed by the Lunar Rover Yutu‐2. Geophysical Research Letters 2019, 46, 12764 -12770.

AMA Style

Kaichang Di, Meng‐Hua Zhu, Zongyu Yue, Yangting Lin, Wenhui Wan, Zhaoqin Liu, Sheng Gou, Bin Liu, Man Peng, Yexin Wang, Shengli Niu, Jinhai Zhang, Jian Li, Jianfeng Xie, Luhua Xi, Jianfeng Yang, Bin Xue. Topographic Evolution of Von Kármán Crater Revealed by the Lunar Rover Yutu‐2. Geophysical Research Letters. 2019; 46 (22):12764-12770.

Chicago/Turabian Style

Kaichang Di; Meng‐Hua Zhu; Zongyu Yue; Yangting Lin; Wenhui Wan; Zhaoqin Liu; Sheng Gou; Bin Liu; Man Peng; Yexin Wang; Shengli Niu; Jinhai Zhang; Jian Li; Jianfeng Xie; Luhua Xi; Jianfeng Yang; Bin Xue. 2019. "Topographic Evolution of Von Kármán Crater Revealed by the Lunar Rover Yutu‐2." Geophysical Research Letters 46, no. 22: 12764-12770.

Journal article
Published: 01 November 2019 in Remote Sensing
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High-accuracy indoor positioning is a prerequisite to satisfy the increasing demands of position-based services in complex indoor scenes. Current indoor visual-positioning methods mainly include image retrieval-based methods, visual landmarks-based methods, and learning-based methods. To better overcome the limitations of traditional methods such as them being labor-intensive, of poor accuracy, and time-consuming, this paper proposes a novel indoor-positioning method with automated red, green, blue and depth (RGB-D) image database construction. First, strategies for automated database construction are developed to reduce the workload of manually selecting database images and ensure the requirements of high-accuracy indoor positioning. The database is automatically constructed according to the rules, which is more objective and improves the efficiency of the image-retrieval process. Second, by combining the automated database construction module, convolutional neural network (CNN)-based image-retrieval module, and strict geometric relations-based pose estimation module, we obtain a high-accuracy indoor-positioning system. Furthermore, in order to verify the proposed method, we conducted extensive experiments on the public indoor environment dataset. The detailed experimental results demonstrated the effectiveness and efficiency of our indoor-positioning method.

ACS Style

Runzhi Wang; Wenhui Wan; Kaichang Di; Ruilin Chen; Xiaoxue Feng. A High-Accuracy Indoor-Positioning Method with Automated RGB-D Image Database Construction. Remote Sensing 2019, 11, 2572 .

AMA Style

Runzhi Wang, Wenhui Wan, Kaichang Di, Ruilin Chen, Xiaoxue Feng. A High-Accuracy Indoor-Positioning Method with Automated RGB-D Image Database Construction. Remote Sensing. 2019; 11 (21):2572.

Chicago/Turabian Style

Runzhi Wang; Wenhui Wan; Kaichang Di; Ruilin Chen; Xiaoxue Feng. 2019. "A High-Accuracy Indoor-Positioning Method with Automated RGB-D Image Database Construction." Remote Sensing 11, no. 21: 2572.

Journal article
Published: 14 May 2019 in Remote Sensing
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Simultaneous localization and mapping (SLAM) methods based on an RGB-D camera have been studied and used in robot navigation and perception. So far, most such SLAM methods have been applied to a static environment. However, these methods are incapable of avoiding the drift errors caused by moving objects such as pedestrians, which limits their practical performance in real-world applications. In this paper, a new RGB-D SLAM with moving object detection for dynamic indoor scenes is proposed. The proposed detection method for moving objects is based on mathematical models and geometric constraints, and it can be incorporated into the SLAM process as a data filtering process. In order to verify the proposed method, we conducted sufficient experiments on the public TUM RGB-D dataset and a sequence image dataset from our Kinect V1 camera; both were acquired in common dynamic indoor scenes. The detailed experimental results of our improved RGB-D SLAM were summarized and demonstrate its effectiveness in dynamic indoor scenes.

ACS Style

Runzhi Wang; Wenhui Wan; Yongkang Wang; Kaichang Di. A New RGB-D SLAM Method with Moving Object Detection for Dynamic Indoor Scenes. Remote Sensing 2019, 11, 1143 .

AMA Style

Runzhi Wang, Wenhui Wan, Yongkang Wang, Kaichang Di. A New RGB-D SLAM Method with Moving Object Detection for Dynamic Indoor Scenes. Remote Sensing. 2019; 11 (10):1143.

Chicago/Turabian Style

Runzhi Wang; Wenhui Wan; Yongkang Wang; Kaichang Di. 2019. "A New RGB-D SLAM Method with Moving Object Detection for Dynamic Indoor Scenes." Remote Sensing 11, no. 10: 1143.

Journal article
Published: 21 March 2019 in Icarus
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The morphometric characteristics of the Kaidu River and Keriya River in the extremely arid Tarim Basin, and the Evros Vallis on Mars were compared to study the formation of the dendritic Evros Vallis, which has great significance for exploring ancient climate of Mars. The following results were obtained: (a) the average sinuosities of Kaidu River, Keriya River, and Evros Vallis are 1.17, 1.35, and 1.32 respectively. (b) the average bifurcation ratios are 3.84, 4.73 and 3.43 respectively. (c) the average stream length ratios are 2.21, 3.86 and 2.08 respectively. (d) the stream frequencies are 0.017, 0.028 and 0.002 respectively. (e) the drainage densities are 0.195 km−1 and 0.217 km−1, and 0.048 km−1 respectively. (f) the stream gradients are 3.74‰, 7.03‰ and 1.63‰ respectively. (g) the stream fractal dimensions are 1.70, 1.0 and 1.68 respectively. Paleodischarge estimations at different stream segments of Evros Vallis support the hypothesis that the V-bend area that joints the eastern and western segments possibly has a tectonic origin. Geomorphological evidence (e.g., tributaries) from high-resolution images and stream morphometric parameters from a comparative analysis (e.g., concave upward longitudinal profile and stream fractal dimension) support previous hypothesis that Evros Vallis is a mature drainage system formed by precipitation-driven surface runoff. This drainage process occurred either in a continuously warm-wet climate that lasted long enough on early Mars or in regional hydrologic cycles consisting of precipitation and occasionally returned runoff in intermittently clement climates.

ACS Style

Sheng Gou; Zongyu Yue; Kaichang Di; Yi Xu. Comparative study between rivers in Tarim Basin in northwest China and Evros Vallis on Mars. Icarus 2019, 328, 127 -140.

AMA Style

Sheng Gou, Zongyu Yue, Kaichang Di, Yi Xu. Comparative study between rivers in Tarim Basin in northwest China and Evros Vallis on Mars. Icarus. 2019; 328 ():127-140.

Chicago/Turabian Style

Sheng Gou; Zongyu Yue; Kaichang Di; Yi Xu. 2019. "Comparative study between rivers in Tarim Basin in northwest China and Evros Vallis on Mars." Icarus 328, no. : 127-140.

Journal article
Published: 01 November 2018 in Planetary and Space Science
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ACS Style

Bin Liu; Mengna Jia; Kaichang Di; Jürgen Oberst; Bin Xu; Wenhui Wan. Geopositioning precision analysis of multiple image triangulation using LROC NAC lunar images. Planetary and Space Science 2018, 162, 20 -30.

AMA Style

Bin Liu, Mengna Jia, Kaichang Di, Jürgen Oberst, Bin Xu, Wenhui Wan. Geopositioning precision analysis of multiple image triangulation using LROC NAC lunar images. Planetary and Space Science. 2018; 162 ():20-30.

Chicago/Turabian Style

Bin Liu; Mengna Jia; Kaichang Di; Jürgen Oberst; Bin Xu; Wenhui Wan. 2018. "Geopositioning precision analysis of multiple image triangulation using LROC NAC lunar images." Planetary and Space Science 162, no. : 20-30.

Journal article
Published: 20 October 2018 in Sensors
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In the study of indoor simultaneous localization and mapping (SLAM) problems using a stereo camera, two types of primary features—point and line segments—have been widely used to calculate the pose of the camera. However, many feature-based SLAM systems are not robust when the camera moves sharply or turns too quickly. In this paper, an improved indoor visual SLAM method to better utilize the advantages of point and line segment features and achieve robust results in difficult environments is proposed. First, point and line segment features are automatically extracted and matched to build two kinds of projection models. Subsequently, for the optimization problem of line segment features, we add minimization of angle observation in addition to the traditional re-projection error of endpoints. Finally, our model of motion estimation, which is adaptive to the motion state of the camera, is applied to build a new combinational Hessian matrix and gradient vector for iterated pose estimation. Furthermore, our proposal has been tested on EuRoC MAV datasets and sequence images captured with our stereo camera. The experimental results demonstrate the effectiveness of our improved point-line feature based visual SLAM method in improving localization accuracy when the camera moves with rapid rotation or violent fluctuation.

ACS Style

Runzhi Wang; Kaichang Di; Wenhui Wan; Yongkang Wang. Improved Point-Line Feature Based Visual SLAM Method for Indoor Scenes. Sensors 2018, 18, 3559 .

AMA Style

Runzhi Wang, Kaichang Di, Wenhui Wan, Yongkang Wang. Improved Point-Line Feature Based Visual SLAM Method for Indoor Scenes. Sensors. 2018; 18 (10):3559.

Chicago/Turabian Style

Runzhi Wang; Kaichang Di; Wenhui Wan; Yongkang Wang. 2018. "Improved Point-Line Feature Based Visual SLAM Method for Indoor Scenes." Sensors 18, no. 10: 3559.

Review
Published: 27 March 2018 in Journal of Sensors
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The Scheimpflug camera offers a wide range of applications in the field of typical close-range photogrammetry, particle image velocity, and digital image correlation due to the fact that the depth-of-view of Scheimpflug camera can be greatly extended according to the Scheimpflug condition. Yet, the conventional calibration methods are not applicable in this case because the assumptions used by classical calibration methodologies are not valid anymore for cameras undergoing Scheimpflug condition. Therefore, various methods have been investigated to solve the problem over the last few years. However, no comprehensive review exists that provides an insight into recent calibration methods of Scheimpflug cameras. This paper presents a survey of recent calibration methods of Scheimpflug cameras with perspective lens, including the general nonparametric imaging model, and analyzes in detail the advantages and drawbacks of the mainstream calibration models with respect to each other. Real data experiments including calibrations, reconstructions, and measurements are performed to assess the performance of the models. The results reveal that the accuracies of the RMM, PLVM, PCIM, and GNIM are basically equal, while the accuracy of GNIM is slightly lower compared with the other three parametric models. Moreover, the experimental results reveal that the parameters of the tangential distortion are likely coupled with the tilt angle of the sensor in Scheimpflug calibration models. The work of this paper lays the foundation of further research of Scheimpflug cameras.

ACS Style

Cong Sun; Haibo Liu; Mengna Jia; Shengyi Chen. Review of Calibration Methods for Scheimpflug Camera. Journal of Sensors 2018, 2018, 1 -15.

AMA Style

Cong Sun, Haibo Liu, Mengna Jia, Shengyi Chen. Review of Calibration Methods for Scheimpflug Camera. Journal of Sensors. 2018; 2018 ():1-15.

Chicago/Turabian Style

Cong Sun; Haibo Liu; Mengna Jia; Shengyi Chen. 2018. "Review of Calibration Methods for Scheimpflug Camera." Journal of Sensors 2018, no. : 1-15.