Ratiometric TOF Depth Mapping with Misaligned Detectors
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Solution Overview
Problem
Conventional Time-of-Flight (TOF) depth mapping systems are costly due to increased resolution requirements in the one-to-ten meter depth range, and suffer from subject motion and parallax errors when using non-optically aligned detectors.
Innovation Solution
The method involves exposing first and second detectors oriented along different optical axes to light from a scene, with the output increasing with light received by the first detector during a specific period and decreasing with light received by the second detector during another period, using a ratiometric TOF approach to compute depth coordinates, thereby reducing costs and parallax errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional TOF depth mapping systems use non-optically aligned detectors, then device complexity is reduced, but measurement precision deteriorates due to parallax errors
Solution Approach 1:
The patent replaces the mechanical/optical alignment requirement with a computational solution. By using multiple detectors with different field of view orientations and applying ratiometric calculations, the system eliminates the need for precise optical alignment while maintaining depth measurement accuracy. The computational processing substitutes for the mechanical alignment that would otherwise be required.
2Measurement precision
If conventional TOF depth mapping systems increase depth resolution, then measurement precision improves, but device complexity and cost increase sharply
Solution Approach 1:
The patent divides the detection function across multiple detectors, each with simpler individual requirements. By segmenting the depth measurement task across several detectors with different field of view orientations and using ratiometric processing, the system achieves high depth resolution without requiring any single detector to have extremely high resolution specifications, thereby reducing overall system complexity and cost.
3Ease of manufacture
If conventional TOF depth mapping systems use non-optically aligned detectors, then ease of manufacture improves, but measurement precision deteriorates due to subject motion and parallax errors
Solution Approach 1:
The patent replaces the mechanical precision requirement with a computational approach. By using detectors with deliberately different field of view orientations and processing the data through ratiometric calculations, the system achieves accurate depth mapping without requiring precise mechanical alignment during assembly, greatly easing manufacturing while maintaining precision.
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 depth mapping accuracy and reduces costs by effectively handling the one-to-ten meter depth range without the drawbacks of subject motion and parallax errors, providing a more efficient and precise 3D representation.
Implementation Method 1
Time-of-flight (TOF) depth mapping is a known approach for constructing a three-dimensional (3D) virtual model of a scene or subject
Data Source
AI summary
A depth-mapping method comprises exposing first and second detectors oriented along different optical axes to light dispersed from a scene, and furnishing an output responsive to a depth coordinate of a locus of the scene. The output increases with an increasing first amount of light received by the first detector during a first period, and decreases with an increasing second amount of light received by the second detector during a second period different than the first.