Structured Light Depth Precision via Hamiltonian Coding
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Solution Overview
Problem
Existing structured light (SL) techniques face challenges in achieving high depth precision, especially in low signal-to-noise ratio (SNR) scenarios and under conditions with ambient light, due to limitations in coding schemes and hardware requirements, which restrict their applicability in time-sensitive and high-precision applications.
Innovation Solution
The implementation of a system that emits K light patterns with trapezoid-shaped waves, based on Hamiltonian cycles of a K-dimensional hypercube, to estimate depths in a scene, using a light source and image sensor with a processor that generates intensity values and determines depth estimates based on these patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional multi-pattern SL techniques are used, then depth accuracy is improved under ideal conditions, but depth precision degrades in demanding conditions with ambient light
Solution Approach 1:
The patent changes the fundamental parameter of the coding scheme from conventional discrete or sinusoidal patterns to Hamiltonian-based continuous patterns. This parameter change enables the system to achieve high depth precision by optimizing the coding curve length and its derivative properties, which directly improves performance in demanding conditions with ambient light while maintaining accuracy under ideal conditions.
Solution Approach 2:
The patent combines multiple mathematical properties (Hamiltonian cycles, hypercube structures, continuous functions) to create a composite coding scheme. This composite approach integrates the benefits of discrete coding (robustness) with continuous coding (precision), resulting in a system that maintains high depth precision across varying lighting conditions including ambient light interference.
2Measurement precision
If laser scanning SL techniques are used, then depth accuracy is improved to 10-100 microns, but acquisition time increases significantly
Solution Approach 1:
The patent employs periodic action by projecting multiple light patterns in rapid succession rather than scanning continuously. The Hamiltonian-based coding scheme allows the system to capture depth information from multiple directions and codes within a single acquisition cycle, significantly reducing the time required to achieve high depth accuracy compared to sequential laser scanning.
Solution Approach 2:
The patent performs preliminary action by pre-designing optimal Hamiltonian coding patterns that encode multiple depth measurements simultaneously. This allows the system to prepare the coding scheme in advance, enabling rapid acquisition of high-precision depth data without requiring time-consuming sequential scanning operations during the actual measurement process.
3Productivity
If single-shot SL techniques are used, then acquisition time is reduced, but depth accuracy decreases due to spatial smoothing
Solution Approach 1:
The patent applies segmentation by dividing the single-shot acquisition into multiple virtual measurements through the Hamiltonian coding scheme. Each projector column is assigned a unique temporal intensity code based on the Hamiltonian cycle, allowing the system to extract multiple depth measurements from a single captured image without spatial smoothing, thereby maintaining both high acquisition speed and depth accuracy.
Solution Approach 2:
The patent transitions from spatial domain encoding to temporal-intensity domain encoding by using Hamiltonian-based coding curves. This dimensional change allows the system to encode depth information along the intensity dimension rather than relying on spatial patterns, eliminating the need for spatial smoothing while maintaining single-shot acquisition capability and high depth precision.
Data Source
AI summary
In accordance with some embodiments, systems, methods and media for encoding structured light imaging patterns and estimating depths in a scene are provided. In some embodiments, a system for estimating depths in a scene is provided, the system comprising: a light source; an image sensor; a hardware processor programmed to: cause the light source to emit K light patterns toward the scene, each of the K light patterns is different and includes a trapezoid-shaped wave, and at least one of the K light patterns includes at least two trapezoid-shaped waves; cause the image sensor to generate an intensity value during emission of each of the K light patterns such that the pixel is associated with at least K intensity values; determine a depth estimate for a portion of the scene imaged by the pixel based on the K intensity values associated with the pixel.