Baseline refinement and DEM accuracy analysis during the in-orbit test phase of LT-1 SAR

doi:10.11947/j.AGCS.2024.20230540.

Abstract

Abstract:

Lutan-1 (LT-1) is the first L-band radar satellite constellation in China primarily utilized for surface deformation measurements.This study utilized SAR data from the LT-1 satellite over the Gansu region to analyze the spatial characteristics of phase ramps in differential interferograms caused by orbital errors. The findings indicated that significant errors in the estimation of parallel baseline component variation rates were the primary factor contributing to orbital phase ramps. In response to some limitations of existing methods, an iterative baseline refinement estimation method based on Fast Fourier Transform (FFT) is developed. Subsequently, three-dimensional surface reconstruction of the study area is conducted based on the corrected baselines. Finally, the quality of the LT-1 DEM product is comprehensively assessed and analyzed using SRTM, AW3D, and Copernicus digital elevation model. Results indicate that the new method effectively corrects residual baseline errors, with an approximately 16.64% improvement in accuracy compared to non-iterative FFT algorithms. The average deviations of the LT-1 DEM from SRTM, AW3D, and Copernicus DEMs are 5.49 m, 3.41 m, and 1.94 m, respectively, demonstrating outstanding elevation accuracy and timeliness advantages.

Key words: Lutan-1, InSAR, orbital error, iterative FFT, DEM accuracy analysis

CLC Number:

P228.4

Xinyou SONG, Lei ZHANG, Tao LI, Baocheng LEI, Ruiqing SONG. Baseline refinement and DEM accuracy analysis during the in-orbit test phase of LT-1 SAR[J]. Acta Geodaetica et Cartographica Sinica, 2024, 53(10): 1920-1929.

Figures/Tables 12

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迭代次数	ΔB_‖/mm	ΔB_⊥/mm	ΔB/mm	/(mm/s)	/(mm/s)	/(mm/s)
1	6.27×10^-3	268.78	268.78	168.34	4.71×10^-4	168.34
2	2.86×10^-3	129.88	129.88	32.68	9.15×10^-5	32.68
3	1.81×10^-3	37.05	37.05	0.28	7.92×10^-7	0.28
4	1.29×10^-3	6.03	6.03	0.25	6.86×10^-7	0.25
5	8.31×10^-4	1.90	1.90	0.21	5.99×10^-7	0.21
6	7.68×10^-4	0.97	0.97	0.18	5.26×10^-7	0.18

名称	观测平台	采集时间	参考基准	空间分辨率/m	绝对精度/m	技术手段
SRTM	航天飞机	2000	WGS-84/EGM96	30/90	<9	InSAR
AW3D	ALOS-1	2006—2011	WGS-84/EGM96	30/90	4.4	光学立体摄影测量
COP DEM	TanDEM-X&TerraSAR-X	2010—2015	WGS-84/EGM2008	30/90	2.1	InSAR
LT-1 DEM	LT-1A/B	2022	WGS-84/椭球面	12.5	—	InSAR