Overview of the GF‐7 Laser Altimeter System Mission

Tang, Xinming; Xie, Junfeng; Liu, Ren; Guo-qin, Huang; Zhao, Chenguang; Zhen, Ying; Tang, Haoyu; Dou, Xiankang

doi:10.1029/2019ea000777

Cited by 43 publications

(26 citation statements)

References 11 publications

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“…In 2014, the first civilian submeter remote sensing satellite, GF-2, which has a spatial resolution better than 1 m (Huang et al 2018), was launched. Subsequently, high-resolution geostationary satellite GF-4 with a maximum data rate of three image captures per minute (Wang et al 2017a), hyperspectral satellite GF-5 with integrated observation capability of land and atmosphere (Sun et al 2018), the first precision agriculture observation satellite GF-6 with ultra-large imaging width (Wang et al 2019), stereo mapping satellite GF-7 with submeter resolution (Tang et al 2019), etc. were launched successively.…”

Section: China's High-resolution Remote Sensing Satellite Developmentmentioning

confidence: 99%

China’s high-resolution optical remote sensing satellites and their mapping applications

Wang

Jiang

2020

Geo-spatial Information Science

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Since the beginning of the twenty-first century, several countries have made great efforts to develop space remote sensing for building a high-resolution earth observation system. Under the great attention of the government and the guidance of the major scientific and technological project of the high-resolution earth observation system, China has made continuous breakthroughs and progress in high-resolution remote sensing imaging technology. The development of domestic high-resolution remote sensing satellites shows a vigorous trend, and consequently, a relatively stable and perfect high-resolution earth observation system has been formed. The development of high-resolution remote sensing satellites has greatly promoted and enriched modern mapping technologies and methods. In this paper, the development status, along with mapping modes and applications of China's high-resolution remote sensing satellites are reviewed, and the development trend in high-resolution earth observation system for global and ground control-free mapping is discussed, providing a reference for the subsequent development of high-resolution remote sensing satellites in China.

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Section: China's High-resolution Remote Sensing Satellite Developmentmentioning

confidence: 99%

China’s high-resolution optical remote sensing satellites and their mapping applications

Wang

Jiang

2020

Geo-spatial Information Science

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“…One of the main instruments onboard TECIS-1 is a three-beam large-footprint waveform lidar [14]. In fact, China has launched their large-footprint lidar systems in 2019 [15], i.e., the seventh satellite in their high-resolution earth observation system (GF-7), although it is not specifically designed for forest monitoring and its pulse rate is only 3 Hz.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Slope-Adaptive Metrics of GEDI Waveforms for Estimations of Forest Aboveground Biomass over Mountainous Areas

Zhang

Sun

2021

J Remote Sens

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Waveform broadening effects of large-footprint lidar caused by terrain slopes are still a great challenge limiting the estimation accuracy of forest aboveground biomass (AGB) over mountainous areas. Slope-adaptive metrics of waveforms were proposed in our previous studies. However, its validation was limited by the unavailability of enough reference data. This study made full validation of slope-adaptive metrics using data acquired by the Global Ecosystem Dynamics Investigation (GEDI) mission, meanwhile exploring GEDI waveforms on estimations of forest AGB. Three types of waveform metrics were employed, including slope-adaptive metrics (RHT), typical height metrics relative to ground peaks (RH), and waveform parameters (WP). In addition to terrain slopes, two other factors were also explored including the geolocation issue and signal start and ending points of waveforms. Results showed that footprint geolocations in the first version GEDI data products were shifted to the left forward of nominal geolocations with a distance of about 24 m~30 m and were substantially corrected in the second version; the fourth and fifth groups of signal start and ending points of waveforms had worse performance than the rest of the four groups because they used the maximum and minimum signal thresholds, respectively. Taking airborne laser scanner (ALS) data as reference, the root mean square error (RMSE) of terrain slopes extracted from the digital elevation model of the shuttle radar topography mission (SRTM DEM) was about 3°. The coefficients of determination (R2) of estimation models of forest AGB based on RH metrics were improved from 0.48 to 0.68 with RMSE decreased from 19.7 Mg/ha to 15.4 Mg/ha by the second version geolocations. The RHT and WP metrics gave the best and the worst estimation accuracy, respectively. RHT further improved R2 to 0.77 and decreased RMSE to 13.0 Mg/ha using terrain slopes extracted from SRTM DEM with a resolution of 1 arc second. R2 of estimation models based on RHT was finally improved to 0.8 with RMSE decreased to 11.7 Mg/ha using exact terrain slopes from ALS data. This study demonstrated the great potential of slope-adaptive metrics of GEDI waveforms on estimations of forest aboveground biomass over mountainous areas.

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“…In flatter regions the elevation accuracy of ICESat/GLAS altimetry data can reach 14 cm (Schutz et al, 2005). This altimetry system has been joined by the ZiYuan3‐02 (ZY3‐02) satellite launched in May 2016, which carries an experimental payload equipped with a laser altimeter for Earth observations (Tang et al, 2016; Li and Tang, 2017; Xie et al, 2018), and the GaoFen‐7 (GF‐7) satellite launched in November 2019 by the China Aerospace Science and Technology Corp. (CASC) (Tang et al, 2019). To maintain a high signal‐to‐noise ratio (SNR) of the laser echo signal, a large spot is designed on satellite laser altimeters to record the three‐dimensional surface.…”

Section: Introductionmentioning

confidence: 99%

Geometric calibration of satellite laser altimeters based on waveform matching

Zhang

et al. 2021

The Photogrammetric Record

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This study proposes a new geometric calibration method for satellite laser altimeters based on waveform matching to solve the problems of poor initial pointing accuracy and a lack of control data. This non‐real‐time method obtains ground control points without a fixed calibration field. First, a large area with stepped surfaces is chosen from the laser altimetry coverage. Then, the laser echo waveforms are simulated using digital surface model (DSM) data of the stepped features. The real echo waveform attempts to match the simulated echo waveforms through a waveform matching model using a global constraint. Next, the control points of the laser altimeter are obtained through waveform matching. Finally, a geometric calibration model for laser altimeters is proposed to compensate for laser pointing and ranging errors. Two experiments were conducted to verify the calibration method using ICESat/GLAS data and airborne large‐footprint laser data. Experimental results confirm that the method is feasible and results in an improvement in the elevation accuracy for the airborne altimeter from 2 to 0.5 m.

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Overview of the GF‐7 Laser Altimeter System Mission

Cited by 43 publications

References 11 publications

China’s high-resolution optical remote sensing satellites and their mapping applications

China’s high-resolution optical remote sensing satellites and their mapping applications

Assessment of Slope-Adaptive Metrics of GEDI Waveforms for Estimations of Forest Aboveground Biomass over Mountainous Areas

Geometric calibration of satellite laser altimeters based on waveform matching

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