SPAD Depth Estimation with Binary Structured Light for Low-Light 3D Scanning
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Solution Overview
Problem
Existing structured light (SL) techniques for 3D imaging face challenges in achieving high precision and speed, particularly in low-light and high-noise conditions, limiting their applicability in industrial inspection and other time-sensitive applications.
Innovation Solution
A system utilizing single-photon detectors and binary structured light patterns, combined with error correction codes like Bose-Chaudhuri-Hocquenghem (BCH) encoding, enables high-speed 3D scanning by projecting and decoding binary light patterns with robustness to photon noise and imaging non-idealities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser scanning SL techniques are used to recover 3D shape accurately, then measurement precision is improved, but acquisition time increases
Solution Approach 1:
The patent segments the light pattern into multiple binary patterns (e.g., 8-16 patterns per depth level) that are projected sequentially. Each pattern encodes depth information for specific depth ranges, allowing the system to acquire depth data across the entire scene through multiple rapid projections rather than scanning line-by-line, thus reducing total acquisition time while maintaining precision
Solution Approach 2:
The system uses periodic projection of binary light patterns at high frame rates (e.g., 100 Hz or higher). By repeatedly projecting patterns and capturing corresponding images, the system accumulates depth information through temporal multiplexing, achieving both speed and accuracy through rapid repeated measurements rather than slow sequential scanning
2Reliability
If binary structured light patterns with error correction codes are used, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent introduces error correction codes (such as BCH codes or Reed-Solomon codes) as an intermediary layer between the projected light patterns and the depth decoding process. These codes add redundancy to the binary patterns, allowing the system to detect and correct photon noise and imaging artifacts during decoding, thereby improving reliability without requiring fundamental changes to the core imaging hardware
Solution Approach 2:
The system modifies the parameters of the light patterns by encoding depth information using binary sequences with specific error correction properties. By changing the pattern structure to include parity bits and redundancy sequences, the system enables robust decoding in the presence of noise while maintaining compatibility with standard single-photon detectors and imaging sensors
3Measurement precision
If single-photon detectors are used to capture binary images, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses an array of single-photon detectors (SPADs) that operate in binary mode (detecting presence or absence of photons during each pattern projection). This copying approach, where multiple simplified detector elements work in parallel across the image sensor array, achieves high measurement precision through statistical accumulation while keeping individual detector complexity low compared to conventional high-resolution cameras
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
The system achieves precise and fast 3D imaging in challenging conditions, including low-albedo objects and strong ambient illumination, with improved decoding accuracy and reduced errors, facilitating high-speed 3D scanning and reconstruction.
Implementation Method 1
an image sensor comprising an array including a plurality of single-photon detectors... each of the plurality of single-photon detectors generates a set of binary values corresponding to the sequence of n binary light patterns
Data Source
AI summary
In accordance with some embodiments, systems, methods, and media for estimating depths in a scene using single-photon detectors and binary structured light patterns are provided. In some embodiments, a system comprises: a light source; an image sensor comprising an array including single-photon detectors; a processor programmed to: cause the light source to emit a sequence of n binary light patterns toward the scene, each comprising at least L columns, each of the patterns has a minimum stripe width of 8 columns; and n>log2(L); cause, for each of the n binary light patterns, the image sensor to capture a binary image of the scene, the binary image comprises a binary value for each of single-photon detectors such that each of the single-photon detectors generates a set of binary values; and estimate, for each single-photon detector, a depth value based on the set of binary values.