Time-of-Flight Camera Synchronization via Modulated Light Detection
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Solution Overview
Problem
Synchronizing the operation of multiple time-of-flight cameras with overlapping fields of view is challenging, especially in environments without a common computer device or network timing protocol, leading to potential false depth profile constructions due to cross-illumination.
Innovation Solution
Designating one camera as a 'master' and others as 'slaves, with predetermined illumination and exposure intervals, allowing slaves to adjust their operations based on the master's illumination to avoid conflicts and ensure synchronized data capture without direct connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple time-of-flight cameras operate independently without synchronization, then each camera can function autonomously, but false depth profile constructions occur due to cross-illumination from overlapping fields of view
Solution Approach 1:
Each time-of-flight camera autonomously determines whether it is receiving light from its own illuminator or another camera's illuminator by analyzing the modulation frequency of the received light. The camera then self-adjusts its exposure timing accordingly, eliminating the need for external synchronization infrastructure while preventing false depth profile constructions.
Solution Approach 2:
The system uses feedback from the sensor's detection of modulated light frequency to control the illuminator's operation. When the sensor detects light at a frequency different from its own illuminator's frequency, it adjusts its exposure timing to avoid capturing cross-illumination, thereby maintaining depth profile accuracy.
2Reliability
If a network timing protocol is used to synchronize multiple time-of-flight cameras, then cross-illumination can be avoided, but the system requires a common computer device and network infrastructure
Solution Approach 1:
Each camera independently determines the modulation frequency of received light and autonomously adjusts its exposure timing without requiring a common computer device or network timing protocol. This enables the system to operate in environments with large numbers of cameras or on independently operated machines such as autonomous vehicles.
Solution Approach 2:
The system changes the operational parameter of exposure timing based on the detected modulation frequency of received light. By dynamically adjusting the exposure timing parameter in response to detected light frequency, the camera adapts to different illumination sources without requiring network coordination.
3Reliability
If the exposure timing of multiple time-of-flight cameras is staggered to prevent cross-illumination, then false depth profiles are avoided, but the cameras cannot operate simultaneously in overlapping fields of view
Solution Approach 1:
The system uses periodic modulated light sources with distinct modulation frequencies for each camera's illuminator. By detecting the modulation frequency of received light, each camera can determine whether the light originates from its own illuminator or another camera's illuminator, enabling simultaneous operation without cross-illumination interference.
Solution Approach 2:
The camera changes its exposure timing parameter based on the detected modulation frequency of received light. When light from another camera's illuminator is detected, the camera adjusts its exposure timing to coincide with periods when that illuminator is not active, allowing simultaneous operation while preventing false depth profiles.
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 effective synchronization of time-of-flight cameras in various environments, preventing false depth profile constructions and allowing for efficient depth imaging data capture without the need for a central control system.
Implementation Method 1
A depth-sensing or range-sensing system that operates by illuminating a scene using a light source and capturing light that is reflected from various points of the scene following the illumination
Implementation Method 2
a sensor for capturing reflected light from the scene. The reflected light that is captured by a time-of-flight camera sensor may be interpreted to generate a depth profile
Data Source
AI summary
Time-of-flight cameras may be synchronized where the fields of view of the time-of-flight cameras overlap. The time-of-flight cameras may be programmed within intervals of time for illuminating their respective fields of view that do not conflict with one another. When a first time-of-flight camera illuminates a first field of view that overlaps with a second field of view of a second time-of-flight camera, and the second time-of-flight camera detects reflected light from the illumination, the second time-of-flight camera may determine a time to illuminate the second field of view based on the reflected light. In this manner, any number of time-of-flight cameras may be synchronized with one another without requiring a direct connection between the time-of-flight cameras.