Single-Photon Lidar Underwater Refraction Correction
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Solution Overview
Problem
Single-photon Lidar underwater terrain and water depth measurement accuracy is compromised due to refraction effects and photon velocity changes in water bodies, leading to deviations in measurement results and reduced positioning and measurement precision.
Innovation Solution
A method and device that correct underwater photon displacement by acquiring pointing angles and coordinates of water-surface and water-bottom photon signals, fitting sea waves to determine a sea wave model, calculating the intersection of photons with the air-water interface, and adjusting coordinates based on wave surface slopes and refraction angles to account for refraction errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If single-photon Lidar is used for underwater measurement, then measurement coverage and detection capability are improved, but measurement precision deteriorates due to refraction effects and photon velocity changes
Solution Approach 1:
The patent applies preliminary action by performing sea wave fitting and determining wave surface slopes before correcting photon coordinates. The system pre-calculates the refraction effects based on wave surface characteristics, then uses these pre-computed parameters to correct the underwater photon positions, thereby improving measurement precision while maintaining broad coverage
Solution Approach 2:
The patent changes physical parameters by incorporating wave surface slope and refraction angle into the coordinate correction process. By dynamically adjusting the correction based on these varying parameters, the system compensates for refraction-induced errors and maintains high positioning accuracy across different measurement conditions
2Ease of operation
If traditional Lidar data processing methods are used, then processing simplicity is maintained, but measurement accuracy deteriorates due to uncorrected refraction effects
Solution Approach 1:
The patent segments the data processing into distinct modules: sea wave fitting, wave surface slope calculation, refraction angle determination, and coordinate correction. This modular approach maintains processing simplicity by organizing complex operations into manageable steps while achieving high measurement accuracy through systematic error correction
3Measurement precision
If refraction correction is applied to improve positioning accuracy, then measurement precision is improved, but device complexity increases due to additional calculation steps
Solution Approach 1:
The patent reduces computational complexity by performing preliminary sea wave fitting and wave surface slope determination before photon coordinate correction. These pre-computed parameters are then reused for correcting multiple photon positions, avoiding redundant calculations and managing device complexity while maintaining high positioning accuracy
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy of underwater terrain and water depth measurements by correcting for refraction-induced errors, improving the precision of two-dimensional and three-dimensional data structures and reducing point position and bathymetry offset errors.
Implementation Method 1
when a photon passes through the atmosphere and hits the water surface, and penetrates the air-water interface into the water, the water body will produce a refraction effect on photons
Implementation Method 2
the transmission speed of photons is caused to decrease
Data Source
AI summary
Methods and devices for correcting underwater photon displacement and for depth sounding with a single-photon Lidar are provided. The method includes: acquiring a pointing angle of a photon emitted by the single-photon Lidar, and coordinates of a water-surface photon signal and a water-bottom photon signal returned by the photon emitted by the single-photon Lidar; performing a sea wave fitting according to the water-surface photon signal to determine a sea wave model; determining an intersection of the photon and an air-water interface according to coordinates of any water-bottom photon, the pointing angle and the sea wave model; determining an underwater displacement error of the photon according to the intersection, the sea wave model and the pointing angle; and correcting the coordinates of the water-bottom photon according to the underwater displacement error. The invention performs sea wave modeling through water surface photon signal and determines intersection of the photon and water-air interface.