A topographic photon extraction method for intertidal zones using ICESat-2 satellite altimeter data

doi:10.11947/j.AGCS.2026.20250419

Abstract

Abstract:

To overcome the limitations of traditional intertidal topographic extraction methods, including limited spatial coverage, high costs, and difficulty in maintaining accuracy under complex environments, this study proposes a topographic photon extraction method for intertidal zones using ICESat-2 satellite altimeter data. Focusing on typical tidal flats and sandy beaches, photon-counting LiDAR data acquired by the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) are used, together with OpenStreetMap (OSM) sandy beach masks and the GWL_FCS30 tidal flat mask, to construct spatial prior constraints for photon confidence screening and type-based zoning. Addressing the characteristic differences between different geomorphic types, scenario-specific extraction strategies are designed. In tidal flat areas, seawater photon removal, skeleton seed extraction, and robust outlier elimination are integrated, and an elliptically shaped density-based spatial clustering of applications with noise (DBSCAN) clustering with adaptive orientation is introduced to accommodate the anisotropic features of gentle slopes and tidal creeks. In sandy beach areas, the ordering points to identify the clustering structure (OPTICS) algorithm based on reachability distance sequences is adopted, and the clustering scale is determined using an Otsu adaptive threshold to adapt to the strongly fluctuating photon density distribution. The results show that the proposed method maintains high extraction accuracy across multiple complex intertidal environments. On the overall validation dataset, the method achieves a Precision of 0.99, a Recall of 0.91, anF₁-score of 0.95, and a Kappa coefficient of 0.90. Further topographic consistency analysis indicates that, at the overall scale, the extracted results differ from reference data by approximately 0.01 m in mean elevation, 0.83 m in elevation range, and 0.46° in slope, demonstrating that the extracted photons can effectively represent intertidal topographic characteristics. This study provides a feasible approach for the application of ICESat-2 data in large-scale, high-precision intertidal topographic monitoring and supports coastal zone management, erosion and accretion assessment, and coastal wetland studies.

Key words: ICESat-2, topography, satellite altimetry, coastal zone, intertidal zone, sea level

CLC Number:

P237

Hao XU, Nan XU, Huichao XIN, Yue MA, Wei TU, Qingquan LI. A topographic photon extraction method for intertidal zones using ICESat-2 satellite altimeter data[J]. Acta Geodaetica et Cartographica Sinica, 2026, 55(4): 658-672.

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References 36

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日期	区域	轨道	剖面类型	平均高程/m		平均高差/m		坡度/（°）
日期	区域	轨道	剖面类型	真值	提取	真值	提取	真值	提取
2024-01-24	辽宁	gt3l	潮滩	2.096	2.167	2.115	1.527	0.035	0.063
2024-02-03	辽宁	gt1l	潮滩	－0.091	0.033	3.056	2.479	0.001	0.001
2024-02-05	辽宁	gt1l	潮滩	0.321	0.344	2.715	2.525	0.027	0.026
2024-02-05	辽宁	gt3l	潮滩	0.695	0.748	3.464	3.237	0.039	0.039
2024-03-21	海南	gt3l	潮滩	1.227	1.259	1.739	1.744	0.098	0.095
2024-03-21	海南	gt3r	潮滩	1.255	1.259	1.839	1.752	0.098	0.098
2019-02-21	山东	gt1l	沙滩	2.959	2.810	4.004	1.939	2.553	1.671
2019-04-22	广东	gt3l	沙滩	1.327	1.353	1.721	1.554	1.359	1.276
2020-07-20	广东	gt2l	沙滩	2.935	2.767	2.610	1.873	1.963	1.407
2021-06-26	广东	gt3r	沙滩	2.678	2.482	3.396	1.179	4.170	1.445
2022-08-29	海南	gt2r	沙滩	2.452	2.608	4.451	1.438	4.603	3.519
2023-01-11	浙江	gt2r	沙滩	3.338	3.477	1.881	1.738	0.694	0.535

类型	N	精确率	召回率	F₁值	Kappa系数	1 m阈值Kappa系数	平均高程/m		1 m阈值平均高程/m	平均高差/m		1 m阈值平均高差/m	平均坡度/（°）		1 m阈值平均坡度/（°）
类型	N	精确率	召回率	F₁值	Kappa系数	1 m阈值Kappa系数	真值	提取	1 m阈值平均高程/m	真值	提取	1 m阈值平均高差/m	真值	提取	1 m阈值平均坡度/（°）
潮滩	40 852	0.995	0.911	0.951	0.889	－	0.917	0.969	－	2.488	2.211	－	0.055	0.054	－
沙滩	4066	0.973	0.807	0.889	0.874	0.669	2.615	2.583	2.340	3.011	1.620	0.979	2.557	1.642	0.806
总体	44 918	0.995	0.909	0.950	0.895	－	1.766	1.776	－	2.749	1.915	－	1.306	0.848	－