Fig. 1. Illustration of dual-frequency laser water/land measurement

Fig. 2. Illustration of components in a green laser full-waveform of water

Fig. 3. Relationships of various reference coordinate systems

Fig. 4. Identification and removal of noisy surface points considering the adjacent laser point pulse number

Fig. 5. Flowchart of the water extraction based on dual-frequency LiDAR point cloud and NDWI-LiDAR

Fig. 6. Location of the airborne LiDAR experiment

Fig. 7. Point clouds of infrared and green lasers. (a) IR laser point cloud; (b) green laser point cloud

Fig. 8. Local probability density distribution of infrared and green laser point elevations

Fig. 9. Spatial distribution of NDWI-LiDAR values in the experimental area

Fig. 10. Probability density distribution of NDWI-LiDAR in the experimental area

Fig. 11. Water/land identification results based on NDWI-LiDAR. (a) Raw water points; (b) corrected water points; (c) raw land points; (d) corrected land points

Fig. 12. Comparison of water extraction results by two LiDAR point clouds. (a) RANSAC; (b) NDWI-LiDAR