Depth-Event Camera Asynchronous Phase Detection
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Solution Overview
Problem
Indirect Time-of-Flight (iToF) depth cameras take time to accumulate reflected light and operate on a per-frame basis, which can lead to inaccuracies in detecting changes in depth due to motion blur and difficulties in distinguishing reflections from specular and transparent surfaces.
Innovation Solution
A depth-event camera system that emits electromagnetic radiation, calculates phase-difference values between emitted and reflected radiation, and triggers events asynchronously when phase differences exceed a threshold, allowing for continuous detection of changes in distance on a per-detector basis, independent of other detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If indirect time-of-flight depth cameras accumulate reflected light on a per-frame basis, then they can generate depth information for the entire scene, but they suffer from motion blur and inaccuracies in detecting depth changes
Solution Approach 1:
The patent divides the depth sensing function into independent per-detector operations, where each detector independently measures phase differences and triggers events for depth changes. This segmentation eliminates the need for frame-based accumulation and resolves motion blur by processing each detector's data independently and continuously.
Solution Approach 2:
The system transitions from static frame-based depth mapping to dynamic event-driven depth change detection. Detectors continuously monitor phase differences and asynchronously trigger events when depth changes exceed thresholds, enabling real-time detection of depth changes without motion blur associated with frame accumulation.
2Productivity
If indirect time-of-flight cameras use per-frame operation, then they can cover the entire field of view, but they cannot rapidly detect depth changes due to frame rate limitations
Solution Approach 1:
The patent implements preliminary comparison of phase differences within each detector before triggering events. Each detector continuously compares current phase measurements with previous values and immediately triggers an event when a depth change is detected, eliminating the delay inherent in frame-based processing and enabling rapid depth change detection.
Solution Approach 2:
The system maintains continuous depth monitoring through asynchronous event triggering at each detector. Instead of periodic frame-based sampling, detectors continuously measure phase differences and trigger events immediately when depth changes occur, providing uninterrupted real-time detection of depth changes throughout the scene.
3Measurement precision
If indirect time-of-flight cameras accumulate light over a frame period, then they can handle low-light conditions, but they introduce motion blur that reduces depth change detection accuracy
Solution Approach 1:
The patent extracts only the phase difference information from the reflected light at each detector, rather than accumulating entire frames. By measuring phase differences continuously and triggering events based on phase changes, the system eliminates motion blur while maintaining sensitivity to depth changes, even in low-light conditions.
Solution Approach 2:
The system changes the measurement parameter from frame-based intensity accumulation to continuous phase difference measurement. Each detector monitors phase changes in real-time and triggers events when phase differences indicate depth changes, providing accurate depth change detection without the motion blur inherent in time-integrated frame accumulation.
4Reliability
If indirect time-of-flight cameras process depth information on a per-frame basis, then they can generate complete depth maps, but they struggle to distinguish reflections from specular and transparent surfaces
Solution Approach 1:
The patent segments the reflection analysis into independent per-detector phase measurements. Each detector independently measures phase differences and triggers events for depth changes, simplifying the discrimination of specular and transparent reflections without requiring complex frame-based processing or additional computational steps.
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
Enables rapid and accurate detection of depth changes with higher spatial and temporal resolution compared to traditional iToF cameras, reducing motion blur and improving depth measurement accuracy, especially in environments with specular and transparent surfaces.
Implementation Method 1
phase-calculation circuitry configured to calculate a phase-difference value indicative of a difference between a phase of the emitted EM radiation and a phase of the reflected EM radiation
Implementation Method 2
a detector configured to receive reflected EM radiation from the environment
Data Source
AI summary
Systems and techniques are described herein for determining changes in distance. For instance, an apparatus for determining changes in distance is provided. The apparatus may include an electromagnetic (EM)-radiation emitter configured to emit EM radiation toward an environment; a detector configured to receive reflected EM radiation from the environment; phase-calculation circuitry configured to calculate a phase-difference value indicative of a difference between a phase of the emitted EM radiation and a phase of the reflected EM radiation; and differencing circuitry configured to trigger an event responsive to a difference between a current phase-difference value and a prior phase-difference value exceeding a threshold.