ToF Camera Parallax Correction for Range Ambiguity Resolution
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Solution Overview
Problem
Conventional time-of-flight cameras face limitations in achieving high depth precision while maintaining a wide measurement range due to the trade-off between modulation frequency and power consumption, and require multiple frequencies for phase unwrapping, which increases power consumption and measurement duration.
Innovation Solution
An apparatus and method that determine a parallax value caused by the spacing between a light source and imager in a ToF camera, using measurement data and a reference value to update the provisional distance value, allowing for improved depth precision and range ambiguity resolution without increasing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If multiple modulation frequencies are used to resolve phase ambiguity and extend measurement range, then measurement range is improved, but power consumption increases
Solution Approach 1:
The patent changes the parameter of modulation frequency from multiple frequencies to a single frequency, while compensating for the loss in measurement range through parallax-based distance estimation. This allows maintaining measurement range capability without the power penalty of multiple frequency measurements.
Solution Approach 2:
The patent introduces parallax as an intermediary mechanism to resolve phase ambiguity. Instead of using multiple frequencies directly, the system uses the parallax effect caused by baseline separation between light source and imager to determine distance and unwrap phases, thereby extending measurement range indirectly.
2Length of stationary object
If multiple modulation frequencies are used to resolve phase ambiguity, then measurement range is improved, but measurement duration increases
Solution Approach 1:
The patent changes the measurement approach from multi-frequency temporal sampling to single-frequency spatial sampling using parallax. This reduces measurement duration by eliminating the need for multiple frequency cycles while maintaining the ability to determine unambiguous distances.
Solution Approach 2:
The patent transitions from resolving ambiguity in the temporal domain (through multiple frequency measurements over time) to resolving it in the spatial domain (through parallax caused by baseline separation). This dimensional shift reduces measurement time while extending range.
3Measurement precision
If higher modulation frequency is used, then depth precision is improved, but measurement range decreases
Solution Approach 1:
The patent uses parallax as an intermediary to extend the effective measurement range of high-frequency measurements. The parallax information provides additional constraints that allow unwrapping phases beyond the nominal unambiguous range of the single high frequency, thereby combining high precision with extended range.
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
Enhances depth precision and accuracy in ToF measurements by resolving range ambiguities using parallax, enabling power savings and reduced motion blur, while maintaining or improving depth noise performance without additional hardware adaptations.
Implementation Method 1
Conventional time-of-flight cameras measure the distance between the camera and the environment in each pixel using a modulated light source and determining the phase caused by the time the light needs to travel from the light source to the object and back to the camera
Implementation Method 2
the ToF camera is configured to perform the ToF measurement by radiating light to a scene by the light source and receiving a reflection of the light by the imager
Data Source
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AI summary
Proposed is an apparatus comprising processing circuitry configured to determine at least one value characterizing a parallax caused by a spacing between a light source and an imager of a ToF camera based on measurement data of a ToF measurement performed by the ToF camera and at least one reference value indicating the parallax. The processing circuitry is configured to determine an updated distance value for a determined provisional distance value for the ToF measurement based on the determined at least one value characterizing the parallax.