SPAD Structured Light Depth Computation with Interleaved Shutter Capture
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Solution Overview
Problem
Conventional structured light depth computation techniques using CMOS and CCD sensors suffer from motion artifacts and spatial misalignment due to moving objects, leading to errors in depth computations.
Innovation Solution
Utilize single photon avalanche diodes (SPADs) with interleaved shutter operations to capture multiple structured light patterns within a single frame capture time period, generating binary counts for each shutter operation to mitigate motion artifacts and improve depth computation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CMOS and CCD sensors are used to capture structured light patterns, then the system can operate with standard sensors, but motion artifacts and spatial misalignment occur leading to depth computation errors
Solution Approach 1:
The patent applies periodic action by using interleaved shutter operations that alternately capture different structured light patterns within a single frame period. Multiple patterns are captured in rapid succession with the shutter opening and closing between each pattern capture, allowing motion-resistant depth computation without requiring multiple complete frame exposures
Solution Approach 2:
The patent segments the frame capture time period into multiple sequential shutter operations, where each shutter operation captures a different structured light pattern. This segmentation allows the system to treat each pattern capture as a separate temporal event, enabling motion artifact mitigation by properly associating each captured pattern with its corresponding temporal window
2Loss of information
If multiple structured light patterns are captured sequentially over multiple frame periods, then complete pattern information can be obtained, but motion artifacts and spatial misalignment increase
Solution Approach 1:
The system captures multiple structured light patterns within a single frame period by performing sequential shutter operations at different time points during the frame exposure. This periodic sampling approach ensures that all pattern information is collected before significant scene motion occurs, eliminating the temporal separation that causes motion artifacts in conventional multi-frame approaches
Solution Approach 2:
The shutter operations are performed continuously within the frame capture time period without interrupting the overall imaging process. The useful action of capturing structured light patterns continues uninterrupted through multiple sequential shutter operations, ensuring that depth computation can proceed without the temporal gaps that would introduce motion-related errors
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
The interleaved exposure method using SPADs reduces motion artifacts and spatial misalignment, enhancing the accuracy and usability of structured light depth imaging by ensuring consistent capture of light pattern images despite scene or sensor motion.
Implementation Method 1
single photon avalanche diodes (SPADs) with interleaved shutter operations to capture multiple structured light patterns
Data Source
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AI summary
A system for structured light depth computation using single photon avalanche diodes (SPADs) is configurable to, over a frame capture time period, selectively activate the illuminator to perform interleaved structured light illumination operations. The interleaved structured light illumination operations comprise alternately emitting at least a first structured light pattern from the illuminator and emitting at least a second structured light pattern from the illuminator. The system is also configurable to, over the frame capture time period, perform a plurality of sequential shutter operations to configure each SPAD pixel of the SPAD array to enable photon detection. The plurality of sequential shutter operations generates, for each SPAD pixel of the SPAD array, a plurality of binary counts indicating whether a photon was detected during each of the plurality of sequential shutter operations.