Fig. 1. Point cloud diagram of ATLAS

Fig. 2. Neighborhood diagram of calculating point density

Fig. 3. Flow chart of sea surface signal extraction

Fig. 4. Point cloud diagram after rough extraction

Fig. 5. Point cloud diagram after refined extraction

Fig. 6. The sea surface signal extraction results: the red points are the original point clouds, and the black points are the sea surface signal points extracted by the method in this paper. (a1) Daytime original point cloud; (a2) Extracted result of daytime point cloud; (b1) Nighttime original point cloud; (b2) Extracted result of nighttime point cloud

Fig. 7. (a) Result of obtaining the sea surface profile; (b) Enlarged view of the blue box area of the obtained result of the sea surface profile

Fig. 8. Amplitude-frequency diagram of sea surface profile obtained by FFT transformation

Table 1. Parameters and calculation results of the study area

Table 2. Comparison of peak wave period errors calculated by the method in this paper and the sea surface signal photons extracted with the official ATL03 high confidence data