Scanned-beam depth mapping with modulated illumination
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Solution Overview
Problem
Existing depth mapping technologies face challenges in achieving high two-dimensional map resolution and frame rate, providing fine and invariant depth resolution over shallow depth ranges, and integrating with low-cost 2D imaging technology.
Innovation Solution
A method involving a camera capturing 2D images with a moving-mirror beam scanner and photodetector to scan a modulated illumination beam over a subject, measuring the modulation aspect of reflected light to compute depth information and associate it with corresponding pixels, enabling the construction of a 3D representation that includes both brightness and depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional depth mapping methods are used to achieve high 2D map resolution and frame rate, then depth mapping performance is improved, but system cost and complexity increase
Solution Approach 1:
The patent combines depth mapping functionality with a standard 2D camera system by integrating a moving-mirror beam scanner that directs a modulated illumination beam across the scene. The same camera sensor captures both 2D images and depth information by detecting the modulation aspect of reflected light, merging multiple functions into a single integrated system rather than using separate depth mapping and imaging systems.
Solution Approach 2:
The patent replaces complex mechanical depth sensing mechanisms with an optical modulation detection approach. Instead of using mechanical time-of-flight sensors or structured light projectors, the system uses a photodetector to measure the modulation aspect of light reflected from a modulated illumination beam, substituting mechanical complexity with optical detection.
2Measurement precision
If traditional depth mapping methods are used to provide fine depth resolution, then measurement precision is improved, but frame rate decreases
Solution Approach 1:
The patent uses periodic modulation of the illumination beam intensity to encode depth information. The modulated beam illuminates the scene at a known frequency, and the photodetector detects the modulation aspect of the reflected light, allowing depth calculation based on the periodic signal characteristics. This periodic approach enables continuous depth mapping at high frame rates without sacrificing resolution.
Solution Approach 2:
The system performs preliminary calibration to establish the relationship between modulation aspect measurements and depth values. During calibration, the system maps the modulation characteristics to known depth distances, creating a lookup table or calibration curve that enables rapid depth calculation during operation without requiring complex real-time computations, thus maintaining high frame rates.
3Measurement precision
If shallow depth ranges are used to achieve fine depth resolution, then measurement precision is improved, but adaptability to varying distances deteriorates
Solution Approach 1:
The patent employs dynamic adjustment of the modulation frequency and beam scanning parameters to adapt to varying depths in the scene. The system can modify the illumination modulation characteristics based on the measured depth range, optimizing the measurement precision for each depth zone while maintaining coverage across a wide overall depth range, making the system versatile for different application scenarios.
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 allows for high-resolution depth mapping with invariant depth resolution across varying distances, effectively combining with low-cost 2D imaging technology to create accurate 3D models.
Implementation Method 1
measuring a modulation aspect of light from the illumination beam reflected from each of the target regions
Implementation Method 2
scanning a modulated illumination beam over the subject to illuminate, one at a time, a plurality of target regions
Data Source
AI summary
A method for constructing a 3D representation of a subject comprises capturing, with a camera, a 2D image of the subject. The method further comprises scanning a modulated illumination beam over the subject to illuminate, one at a time, a plurality of target regions of the subject, and measuring a modulation aspect of light from the illumination beam reflected from each of the target regions. A moving-mirror beam scanner is used to scan the illumination beam, and a photodetector is used to measure the modulation aspect. The method further comprises computing a depth aspect based on the modulation aspect measured for each of the target regions, and associating the depth aspect with a corresponding pixel of the 2D image.