Resolving Multipath Corruption in Time-of-Flight Depth Imaging
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Solution Overview
Problem
Time-of-flight (ToF) imaging systems face challenges in accurately determining distance due to multipath effects, where light rays travel different distances before returning to the pixel, leading to corrupted depth estimates, especially with nearby reflective surfaces.
Innovation Solution
The system increases the number of measurements by collecting depth images at different frequencies and uses nonsinusoidal light signals, processing these measurements to resolve multipath bounces through dimensionality reduction and discretization, with a lookup table storing precomputed solutions for corrected depth data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sinusoidal light signals are used with multiple measurements at different frequencies, then multipath corruption can be resolved, but frame rate decreases and power consumption increases
Solution Approach 1:
The patent uses periodic light signals to illuminate the scene, where the light source emits light in periodic pulses. By using nonsinusoidal periodic waveforms with specific duty cycles, the system can resolve multipath corruption while maintaining higher frame rates compared to traditional sinusoidal approaches that require multiple frequency measurements.
Solution Approach 2:
The patent changes the waveform parameter from sinusoidal to nonsinusoidal (such as square wave or pulse wave) to achieve multipath resolution. This parameter change allows the system to obtain sufficient measurement information without requiring multiple frequency measurements, thereby improving frame rate while maintaining depth measurement accuracy.
2Measurement precision
If sinusoidal light signals with multiple frequency measurements are used, then multipath corruption can be resolved, but power consumption increases
Solution Approach 1:
The system employs periodic nonsinusoidal light signals that can resolve multipath effects in a single measurement phase, eliminating the need for multiple frequency measurements. This reduces the total energy consumed during the measurement process while maintaining depth measurement accuracy.
Solution Approach 2:
By changing the light signal waveform parameter from sinusoidal to nonsinusoidal, the system achieves multipath resolution with reduced measurement time and lower power consumption, as the nonsinusoidal waveform provides sufficient information content in a single measurement phase.
3Device complexity
If traditional sinusoidal measurements are used, then the system operates simpler, but multipath corruption significantly degrades performance
Solution Approach 1:
The patent changes the fundamental parameter of the light signal from sinusoidal to nonsinusoidal waveform. This simple parameter change enables the system to resolve multipath corruption without significantly increasing processing complexity, as the nonsinusoidal waveform's harmonic content provides natural separation of multipath components.
Solution Approach 2:
The patent converts the harmful effect of multipath reflection into a beneficial signal characteristic. By using nonsinusoidal waveforms, the multipath reflections contain distinct harmonic information that can be separated and used to resolve the true depth, transforming the corruption into useful measurement data.
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 improves multipath reduction, increases frame rate, reduces power consumption, and enhances the accuracy of depth determination in ToF imaging systems.
Implementation Method 1
a light source configured to emit a nonsinusoidal light signal during a first time interval
Implementation Method 2
The Time-of-Flight principle (ToF) is a method for measuring the distance between a sensor and an object based on the time difference between the emission of a signal and its return to the sensor after being reflected by an object
Implementation Method 3
measuring the time-of-flight of a light signal between the camera and the subject for each point of the image
Data Source
AI summary
Time of Flight (ToF) depth image processing methods are disclosed for resolving corruption of ToF depth images. In ToF depth imaging, the light can travel paths of different lengths before returning to the pixel. Thus, the light hitting the pixel can have travelled different distances, and the distance obtained from an estimation procedure assuming a single distance may be spurious. Systems and methods are disclosed for including a time-of-flight imager and processor which resolves the multiple paths, and outputs the multiple depths at each pixel.