Structured Light Pattern Generation Using Pseudorandom Diffuser
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Solution Overview
Problem
Traditional stereo algorithms for generating depth maps are limited by the quantity of relevant features in a scene and assumptions such as brightness constancy, resulting in restricted depth map resolution and field of view.
Innovation Solution
A system that generates a structured light pattern by passing a coherent light beam through a pseudorandom diffuser element and spatially filtering it with a relay optic, allowing for increased feature resolution, density, and field of view in depth sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional stereo algorithms are used to generate depth maps from color images, then the system can extract three-dimensional information, but the depth map resolution and field of view are limited by the quantity of relevant features in the scene
Solution Approach 1:
The system performs preliminary action by projecting a structured light pattern onto the scene before capturing depth information. This pre-illumination with known geometric patterns creates artificial features that can be detected regardless of the scene's natural feature content, thereby resolving the limitation of insufficient relevant features for achieving high depth map resolution
Solution Approach 2:
A structured light pattern serves as an intermediary between the light source and the scene. This intermediate element carries encoded geometric information that, when projected onto the scene and captured by the camera, enables precise depth measurement without relying on the quantity of natural features in the scene
2Area of stationary object
If traditional stereo algorithms are used, then depth information can be extracted, but the field of view and feature density are restricted
Solution Approach 1:
The system transitions from relying on two-dimensional image feature matching to incorporating a third dimension through structured light projection. By encoding depth information directly into the projected light pattern's geometry, the system achieves high feature resolution across an extended field of view without being constrained by the original two-dimensional stereo algorithm limitations
3Measurement precision
If a diffractive optic element is used to generate structured light pattern, then depth sensing can be performed, but the resolution and depth of field are limited by fabrication processes
Solution Approach 1:
The system replaces the mechanical/diffractive optic element approach with a computational imaging approach. Instead of relying on physically fabricated diffractive patterns with inherent resolution and depth of field limits, the system uses programmable light projection and algorithmic processing to achieve high-resolution depth sensing without being constrained by manufacturing capabilities
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 enhances depth map resolution and field of view, enabling more accurate geometric information extraction and improved active depth sensing capabilities compared to existing technologies.
Implementation Method 1
passing a coherent light beam through a pseudorandom diffuser element. Light output from the pseudorandom diffuser element is spatially filtered and projected
Implementation Method 2
A structured infrared (IR) pattern is projected onto the scene and photographed by a single IR camera. Based on deformations of the light pattern, geometric information about the underlying video scene can be determined
Implementation Method 3
A relay optic is positioned to receive the intermediate speckle illumination from the pseudorandom diffuser element. The relay optic spatially filters the intermediate speckle illumination to generate an output speckle illumination
Data Source
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AI summary
A pattern projector disclosed herein generates and projects a structured light pattern suitable for use in a variety of active depth sensing technologies. In one implementation, a structured light pattern is generated by directing a coherent light beam through a pseudorandom diffuser element. Output of the pseudorandom diffuser element is received by a relay optic configured to spatially filter incident light to generate an output speckle illumination and to project the output speckle illumination to a three-dimensional scene.