Hamiltonian Coding for Time-of-Flight Depth Resolution
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Solution Overview
Problem
Current continuous-wave Time-of-Flight (C-ToF) camera systems suffer from limited depth resolution, particularly in low signal-to-noise ratio (SNR) scenarios, due to noise limitations, and existing coding schemes do not offer sufficient precision for consumer and outdoor applications where power and time are constrained.
Innovation Solution
The implementation of a system using modulation and demodulation functions based on Hamiltonian coding schemes, which include modulation functions and demodulation functions that characterize a coding curve on a K-dimensional hypercube, enabling more precise depth estimation by minimizing noise errors and improving depth resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sinusoid or square wave coding schemes are used in C-ToF systems, then the system can operate with low-cost components and low power consumption, but the depth resolution is fundamentally limited by noise and cannot achieve high precision in low SNR scenarios
Solution Approach 1:
The patent applies parameter changes by transforming the coding scheme from conventional sinusoid or square wave modulations to Hamiltonian coding schemes. This changes the fundamental parameters of the modulation function, allowing the system to achieve higher depth resolution (up to 10 times better than existing methods) while operating with low-cost components and low power consumption. The Hamiltonian coding scheme modifies the temporal modulation pattern to maximize the coding curve length, which directly improves depth precision without requiring higher power or more expensive hardware.
2Measurement precision
If more powerful light sources or longer capture times are used to increase SNR, then depth resolution may improve, but this is not feasible in consumer and outdoor settings where power and time are constrained
Solution Approach 1:
The patent resolves this contradiction by changing the modulation parameter from conventional waveforms to Hamiltonian coding schemes. This parameter change allows the system to achieve high depth resolution without increasing power consumption or capture time. The Hamiltonian coding scheme is specifically designed to maximize measurement precision within the given power and time constraints, making it suitable for consumer and outdoor applications where these resources are limited.
3Measurement precision
If conventional coding schemes are used, then the system complexity remains low and implementation is simple, but the depth precision is insufficient for applications requiring high accuracy over large standoff distances
Solution Approach 1:
The patent applies parameter changes by transitioning from simple sinusoid or square wave coding to Hamiltonian coding schemes. While this increases the complexity of the coding scheme, it dramatically improves depth precision (up to 10 times better). The increased complexity is in the form of more sophisticated temporal modulation patterns, but the underlying hardware architecture remains the same, allowing the system to achieve high precision without requiring completely new hardware designs.
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
Hamiltonian coding schemes achieve significantly higher depth resolution, up to 10 times better than existing methods, given the same capture time, power, and depth range, effectively enhancing the precision of depth measurements in C-ToF imaging systems.
Implementation Method 1
Impulse ToF (sometimes referred to as direct ToF) systems estimate scene depths by emitting a short light pulse into the scene, and directly measuring the travel time of the reflected pulse
Implementation Method 2
an image sensor comprising a plurality of pixels; cause the image sensor to generate a first value based on the modulated light received from a portion of the scene
Data Source
AI summary
In accordance with some embodiments, systems, methods and media for encoding and decoding signals used in time-of-flight imaging are provided. In some embodiments, a method for estimating the depth of a scene is provided, comprising: causing a light source to emit modulated light toward the scene based on a modulation function; causing the image sensor to generate a first value based on the modulated light and a first demodulation function of K modulation functions, including at least one trapezoid wave; causing the image sensor to generate a second value; causing the image sensor to generate a third value; and determining a depth estimate for the portion of the scene based on the first value, the second value, and the third value.