Depth Camera Synchronization via Time Division Multiplexing
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Solution Overview
Problem
Multiple depth cameras used in active sensing systems often interfere with each other, leading to degraded accuracy in 3D model reconstruction due to overlapping structured light patterns and limited field of view, especially when trying to capture a 360-degree model of an object.
Innovation Solution
Implementing a system where each depth sensing device projects and receives light as a series of pulses, with the duration and frequency of these pulses adjusted based on the presence of light from other devices, allowing for simultaneous operation without interference by synchronizing exposure windows and pulse lengths to avoid overlap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple depth cameras are used simultaneously to extend field of view and improve 3D model quality, then the coverage area and model completeness are improved, but the structured light patterns overlap causing interference and degrading measurement precision
Solution Approach 1:
The patent applies periodic action by implementing time-division multiplexing where multiple depth cameras operate in alternating time slots rather than simultaneously. Each camera is activated during its designated time window, projecting structured light patterns and capturing depth information sequentially. This periodic activation eliminates pattern overlap and mutual interference while maintaining extended field of view coverage, as each camera operates during its own time period without conflicting with others.
2Productivity
If multiple depth cameras operate simultaneously to capture 360-degree models, then the productivity of scene scanning is improved, but the structured light patterns interfere with each other causing harmful effects
Solution Approach 1:
The system implements periodic action through time-division multiplexing, where each depth camera is activated in sequential time slots rather than simultaneously. This periodic activation pattern allows multiple cameras to capture scene data efficiently while eliminating light pattern interference, as only one camera projects and receives light at any given moment. The scene scanning productivity is maintained by coordinating the time slots to cover the entire 360-degree view.
Solution Approach 2:
The patent applies segmentation by dividing the scene scanning task into separate time segments, with each depth camera assigned to specific time windows. This temporal segmentation prevents interference between cameras while maintaining high productivity, as the system systematically progresses through different time slots to capture complete scene coverage. Each camera segment operates independently without conflicting with others.
3Reliability
If the pulse duration is extended to improve signal detection, then the sensitivity of light detection is improved, but the time window for other cameras to operate without interference is reduced
Solution Approach 1:
The patent applies dynamics by implementing adaptive pulse duration adjustment based on scene conditions and camera position. The pulse width is dynamically optimized to provide sufficient detection sensitivity for each specific imaging scenario while maintaining adequate time slots for other cameras in the time-division multiplexed system. This dynamic adjustment allows the system to achieve reliable signal detection without unnecessarily extending pulse duration, thereby preserving time resources for comprehensive multi-camera coverage.
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 enables multiple depth cameras to operate simultaneously without interference, improving the quality of 3D model reconstruction by minimizing aberrations and allowing for a comprehensive 360-degree view of an object without degrading the accuracy of individual camera readings.
Implementation Method 1
a transmitter capable of projecting light on a scene, the transmitter comprising a laser capable of producing a light beam including a series of laser pulses
Implementation Method 2
the receiver comprising a shutter and a sensor assembly capable of producing an image based on sensing light projected by the transmitter and reflected from the scene
Data Source
AI summary
Aspects relate to a depth sensing system for capturing an image containing depth information of an object. In one embodiment, a depth sensing device for use in conjunction with multiple depth sensing devices for capturing an image containing depth information of an object comprises a near-infrared transmitter comprising a laser capable of producing a near infra-red light beam, a diffractive optical element positioned to receive a light beam emitted from the laser, the diffractive optical element, a collimating lens, and a near-infrared receiver coupled to the transmitter in a relative position, the receiver comprising a sensor assembly capable of producing an image of the received light, the depth sensing device being configured to transmit and receive near infra-red light beams during a time period that is different than any of the other of two or more transmitter-receiver pairs of devices in communication with the depth sensing device.