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Future Power Generation And the Environment
Published in Anco S. Blazev, Power Generation and the Environment, 2021
Providing a lot of information about the unknown and invisible events around us, and putting our fears into perspective is the main role of our smart companions high up in space. Earth observation satellites are a special type of satellites specifically designed to observe Earth from orbit. They function like spy satellites but are intended for non-military uses, such as environmental monitoring, meteorology, and map making. Most Earth observation satellites operate at altitudes above 500 kilometers to reduce the significant air-drag that is present at low altitudes, which forces frequent orbit maneuvers.
Satellites
Published in Mohammad Razani, Commercial Space Technologies and Applications, 2018
Earth Observation Satellites are satellites specifically designed for Earth observation from orbit, similar to spy satellites but intended for non-military uses such as environmental monitoring, meteorology, map making, etc.
Geometric calibration method based on Euler transformation for a large field of view polarimetric imager
Published in Journal of Modern Optics, 2020
Chan Huang, Yuyang Chang, Lin Han, Su Wu, Shuang Li, Donggen Luo, Liang Sun, Jin Hong
The DPC is the first Chinese multi-angle polarized earth observation satellite sensor. In this paper, first, the optical principle and the geometric model of the DPC are introduced. Then, after analysing the alignment error and system error of the original DPC geometric method, an improved geometric calibration method based on a two-dimensional turntable and Euler transformation with high precision, simple operation, and wide application range is proposed for the DPC. The method introduces rotation matrix and translation vector to effectively eliminate error factors. The geometric calibration verification experiments of the directional polarimetric camera were carried out in the laboratory with the original method without Euler transformation and the proposed method. The experimental results show the calibration residuals of the proposed method are less than 0.2 pixel while the maximum residual of the original method reaches about 0.35 pixel. The root mean squared error and mean reprojection error are reduced from 2.36 × 10−1 and 2.15 × 10−1 of the original method to 1.02 × 10−1 pixel and 9.82 × 10−2 pixel of the proposed method, respectively. These facts prove the effectiveness and superiority of the proposed method. Higher precision geometric calibration would promote the application of the DPC in the field of remote sensing. Since this method does not need complex equipment but only a two-dimensional turntable, it can be easily applied to the geometric calibration of other cameras.
Phenological metrics-based crop classification using HJ-1 CCD images and Landsat 8 imagery
Published in International Journal of Digital Earth, 2018
Xiaochun Zhang, Qinxue Xiong, Liping Di, Junmei Tang, Jin Yang, Huayi Wu, Yan Qin, Rongrui Su, Wei Zhou
The Landsat 8 system is the eighth American Earth observation satellite in the Landsat program. Landsat 8 OLI has a spatial resolution of 30 m for multi-spectral bands and 15 m for the panchromatic band 8, with a revisit time of 16 days. In our study, the Landsat 8 OLI image (path 123 and row 39) from 31 July 2013 was selected for masking non-vegetation areas using its pan-sharpened multi-spectral bands, as it has similar spectral characteristics with the HJ-1 CCD (CCFRSDA 2014a; USGS 2015). The specific comparisons between Landsat 8 OLI imagery and HJ-1 CCD are listed in Table 2. We used the panchromatic band 8 at 15 m resolution, and increased the spatial resolution of the multi-spectral bands (bands 1–7) from 30 m to 15 m by applying the pan-sharpening technique (Johnson, Scheyvens, and Shivakoti 2014). Although the 16-day temporal resolution limits the retrieval of crop biophysical parameters that are rapidly changing during the season, 15 m pan-sharpened Landsat 8 image is more appropriate for smaller non-vegetation surface features for comparisons with 30 m HJ-1 CCD images. Therefore, the Landsat 8 image in July was used for discriminating vegetation areas from non-vegetation areas.
Novel collaborative optimization framework with a negotiation model for satellite system design
Published in Engineering Optimization, 2018
Yunfeng Dong, Xiaona Wei, Fengrui Liu
The CO and improved CO methods are efficient optimization methods for satellite system design (Huang et al. 2014). The Earth observation satellite is designed using four kinds of CO in this study. To validate whether CO with decomposition could address the intensive computational cost of the all-in-one optimization method, the GA, which is used as the optimization algorithm for CO, is applied to the satellite design to represent the all-in-one optimization method. Because the number of independent variables in the all-in-one optimization is far larger than that of system-level or subsystem-level optimizations for the four kinds of CO, the number of individuals in each generation of the all-in-one optimization is 10,000, and the convergence criterion is a stable percentage of less than 0.2% in 100 continuous generations. Optimization is conducted 10 times, and the average performances are shown in Table 4.