Distance Acquisition Using Weighted Phase Modulation
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Solution Overview
Problem
Existing 3D image acquisition methods, such as binocular stereo vision and time-of-flight (TOF), face challenges in achieving precise depth information, especially at greater distances and are affected by surface states and noise types like discontinuous, linear, and quadratic function noise.
Innovation Solution
A method and device that determine the optimal number and order of lights to be emitted, modulate returning lights, and apply weights based on emission order and noise types to improve distance information accuracy, using a processor to control light emission and modulation, and a modulator to apply weights for phase difference and motion blur index calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If binocular stereo vision or triangulation methods are used to obtain depth information, then the system can acquire 3D content, but the accuracy of depth information rapidly decreases when the distance increases
Solution Approach 1:
The patent applies periodic action by emitting multiple lights with different phases (0°, 90°, 180°, 270°) in a periodic sequence and modulating them with periodic waveforms. This periodic emission and modulation scheme enables the system to capture phase difference information at multiple time points, allowing accurate depth measurement even at greater distances by comparing the phase shifts of reflected lights across the periodic cycles.
2Measurement precision
If traditional TOF methods are used with a single light emission, then the process is simple, but the accuracy is affected by various noise types (discontinuous, linear, quadratic function noise)
Solution Approach 1:
The patent segments the depth measurement process by dividing it into multiple light emission events, each with a specific phase (0°, 90°, 180°, 270°). Instead of using a single light emission, the system emits multiple segmented lights and processes each separately, then combines the results. This segmentation allows the system to differentiate and compensate for various noise types (discontinuous, linear, quadratic) by analyzing patterns across the segmented measurements, thereby improving accuracy while managing complexity through systematic processing.
Solution Approach 2:
The patent implements feedback by using the phase difference information obtained from multiple light emissions to calculate and apply weights to each measurement. The system feeds back the phase difference data to determine appropriate weighting factors, which are then applied to the modulated light signals to compensate for noise and improve the final depth measurement accuracy. This feedback mechanism allows the system to adaptively correct for various noise types based on the observed phase differences.
3Reliability
If multiple lights are emitted to reduce noise and improve accuracy, then the depth information becomes more reliable, but the time required for acquisition increases
Solution Approach 1:
The patent maintains continuity of useful action by emitting multiple lights in a continuous periodic sequence rather than as separate discrete events. The lights are emitted continuously with phases 0°, 90°, 180°, 270° in rapid succession, creating an overlapping measurement process where the acquisition of one phase measurement begins before the previous one is fully complete. This continuous emission strategy reduces the total acquisition time while maintaining the reliability benefits of multiple measurements, as the useful action of depth measurement continues uninterrupted throughout the emission sequence.
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 efficiently reduces errors in distance information acquisition by optimizing light emission and modulation, enhancing the accuracy of depth images across varying distances and noise conditions.
Implementation Method 1
TOF is a method of emitting a light onto a subject and then measuring a time it takes for the light to be reflected at the subject and received by a light-receiving unit
Implementation Method 2
the received light is modulated by using a modulator having a known gain waveform
Data Source
AI summary
A method of acquiring distance information about a subject is provided. The method may include: determining a number of a plurality of lights to be emitted to the subject; emitting the determined number of the plurality of lights to the subject; modulating the plurality of lights returning from the subject; determining a weight based on at least one of the plurality of lights emitted to the subject and an emission order of the plurality of lights; and acquiring distance information about the subject by applying the weight to each of the modulated plurality of lights. According to the method, an error is efficiently reduced based on the number of the plurality of lights projected onto the subject.