LT-1 InSAR block adjustment considering the impact of penetration depth in forest areas

doi:10.11947/j.AGCS.2025.20240426

Abstract

Abstract:

Due to its intense penetration, the first L-band interferometric SAR constellation, LuTan-1 (LT-1), has unique advantages in sub-canopy topography mapping. The block adjustment utilizes height control points (spaceborne LiDAR) and tie-points to calibrate the systematic error, which is the basis for LT-1 to carry out large-scale sub-canopy topography mapping. However, to avoid the problem of InSAR altimetry deviation from LiDAR caused by forest scattering, the existing block adjustment methods only select bare-earth points, which are prone to pathological observations with systematic error. Given this, this paper uses the SINC model that describes the forest scattering process to compensate for the InSAR altimetry deviation and establishes a block adjustment model considering the influence of penetration depth. We used two test sites with forest coverage of about 85% and 50% to verify the algorithm's effectiveness. The results show that the LT-1 DEM estimated in this paper improves the height accuracy by 22.1% and 12.5% compared with the traditional method, and the height accuracy and forest penetration rate are at the highest level compared with COP-DEM, SRTM, and AW3D. Furthermore, the LT-1 sub-canopy topography estimated based on the SINC model improved the height measurement accuracy by 40.6% and 25.5% compared with the LT-1 DEM, with RMSE of 3.15 m and 2.80 m, respectively.

Key words: block adjustment, InSAR, LT-1, DEM, sub-canopy topography, SINC model

CLC Number:

P207

Kefu WU, Haiqiang FU, Jianjun ZHU, Qijin HAN, Aichun WANG, Mingxia ZHANG, Zhiwei LI. LT-1 InSAR block adjustment considering the impact of penetration depth in forest areas[J]. Acta Geodaetica et Cartographica Sinica, 2025, 54(6): 1009-1020.

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数据集	数据来源	筛选法则
控制点	ICESat-2 ATL08	1. 利用COP-DEM剔除粗差
		2. 强波束
		3. 云量小于20%
		4. 非InSAR几何畸变区
		5. InSAR相干性大于第60百分位数
		6. 与LT-1 DEM差分相互剔除粗差
连接点	InSAR DEM	1. 坡度小于30°
		2. 非InSAR几何畸变区
		3. InSAR相干性大于第60百分位数
		4. 连接点对差分相互剔除粗差

数据集	发布年份	水平基准	垂直基准	分辨率/m
COP-DEM	2020	WGS-84	EGM2008	30
SRTM V3	2013	WGS-84	EGM96	30
AW3D V2.2	2019	GRS80	EGM96	30
FNF	2019	WGS-84	—	50

地形产品	（0°，5°]		（5°，10°]		（10°，15°]		（15°，20°]		（20°，90°]
地形产品	RMSE	MAE	RMSE	MAE	RMSE	MAE	RMSE	MAE	RMSE	MAE
LT-1 DEM	4.39	3.47	4.96	4.11	5.50	4.56	6.24	5.19	7.25	5.99
林下地形	2.26	1.70	2.79	2.13	3.41	2.63	4.20	3.24	5.45	4.20
COP-DEM	9.01	7.53	10.46	9.41	11.26	10.21	12.16	11.00	13.06	11.51
SRTM	5.40	4.39	6.48	5.51	7.54	6.44	8.84	7.49	10.43	8.68
AW3D	6.20	5.15	7.27	6.28	8.00	6.78	8.40	6.93	9.70	7.72

地形产品	（0°，5°]		（5°，10°]		（10°，15°]		（15°，20°]		（20°，90°]
地形产品	RMSE	MAE	RMSE	MAE	RMSE	MAE	RMSE	MAE	RMSE	MAE
LT-1 DEM	2.31	1.56	3.13	2.32	4.00	3.07	5.15	4.05	6.67	5.30
林下地形	1.84	1.28	2.40	1.77	3.09	2.30	4.06	3.05	5.54	4.17
COP-DEM	4.91	3.28	6.68	5.21	7.83	6.42	9.10	7.59	10.53	8.84
SRTM	3.12	2.39	3.99	3.11	4.82	3.78	5.96	4.71	7.59	6.17
AW3D	3.83	2.88	5.14	4.06	6.23	4.97	7.08	5.56	9.32	7.22

试验区	地形产品	（0°，5°]	（5°，10°]	（10°，15°]	（15°，20°]	（20°，90°]
1	LT-1 DEM	75.6	75.6	76.5	76.5	76.0
	LT-1林下地形	99.2	99.1	99.4	100.5	100.6
	COP DEM	51.7	52.0	48.9	50.9	51.6
	SRTM	68.4	68.2	67.5	61.5	58.9
	AW3D	67.8	67.6	66.7	64.7	63.2
2	LT-1 DEM	77.4	77.8	76.3	74.2	76.7
	LT-1林下地形	99.5	99.0	98.9	99.7	100.2
	COP DEM	54.9	57.0	54.3	48.2	47.6
	SRTM	70.8	71.9	72.8	72.9	70.3
	AW3D	63.9	65.5	65.5	66.0	64.4