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A Directional Nearest Neighbor Distance-Based Algorithm for Signal Photon Extraction from Spaceborne Photon-Counting
Shibin Zhao1,2,3,4, Zhenwei Shi1,2,3, Tingting Jin1,2,3
1Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China.
Sensors (Basel, Switzerland)
|March 14, 2026
Summary
A new Directional Nearest Neighbor Distance-based Algorithm (DNNDA) effectively removes noise from Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) photon data. This method enhances shallow-water bathymetry by improving seafloor signal extraction in noisy conditions.
Area of Science:
- Geospatial science
- Oceanography
- Remote sensing
Background:
- Satellite-derived bathymetry using ICESat-2 data is promising for shallow waters due to its 532 nm laser.
- Effective denoising of photon-counting data is critical due to solar background and instrument noise.
- Existing denoising methods struggle in high-noise environments.
Purpose of the Study:
- To propose a novel photon denoising algorithm (DNNDA) for ICESat-2 shallow-water data.
- To robustly extract seafloor signal photons from noisy ICESat-2 data.
- To improve the accuracy of satellite-derived bathymetry.
Main Methods:
- Developed the Directional Nearest Neighbor Distance-based Algorithm (DNNDA).
- DNNDA exploits scale-corrected spatial relationships and directional photon distribution.
- Incorporated directional features into a density representation to enhance signal-photon contrast.
Main Results:
- DNNDA achieved superior seafloor photon extraction with F1-scores over 95% on global ICESat-2 datasets.
- Regression analysis against CUDEM data showed root-mean-square errors below 0.57 m.
- The algorithm automates optimal parameter determination using a designed evaluation index.
Conclusions:
- DNNDA provides a robust solution for shallow-water bathymetry in complex, high-noise environments.
- The method enables reliable and adaptive signal photon extraction at local and global scales.
- DNNDA overcomes limitations of existing methods by considering directional photon characteristics.
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