AR Headset Depth Camera Switching Modes for Ambient Light

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Solution Overview

Problem

Traditional depth camera imaging architectures for virtual and augmented reality systems, such as time-of-flight, structured light, and stereo vision, face performance degradation in high ambient brightness conditions, leading to ineffective capture of 3D scene information.

Innovation Solution

A headset with a depth camera assembly that includes RGBI cameras and an IR laser, capable of operating in multiple imaging modes based on ambient light levels, using structured light to project patterns and capture images, and adjusting parameters like focal length and ISO to enhance signal-to-noise ratio and capture depth information effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If structured light is used to capture 3D scene information, then depth mapping capability is improved, but performance degrades in high ambient brightness conditions

Engineering Contradiction:
Improvedepth mapping accuracyVSAvoidambient light interference
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system dynamically switches between different imaging modes (stereo vision, structured light, time-of-flight) based on ambient light conditions. The controller monitors brightness levels and automatically selects the optimal imaging mode to maintain depth mapping accuracy across varying environmental conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system adjusts operational parameters such as ISO sensitivity, exposure time, and focal length based on ambient light levels. In high brightness conditions, the system modifies these parameters to optimize the signal-to-noise ratio for structured light capture, thereby maintaining measurement precision despite ambient interference.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If time-of-flight architecture is used, then depth information capture is improved, but performance degrades under increasing ambient brightness

Engineering Contradiction:
Improvedepth information accuracyVSAvoidbackground light interference
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system dynamically switches between different imaging modes (stereo vision, structured light, time-of-flight) based on ambient light conditions. The controller monitors brightness levels and automatically selects the optimal imaging mode to maintain depth mapping accuracy across varying environmental conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system introduces an intermediary selection mechanism (the controller) that chooses between multiple depth sensing technologies based on environmental conditions. This intermediary layer allows the system to bypass the limitations of any single technology under specific lighting conditions by selecting the most appropriate modality.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If stereo vision is used, then performance in low light conditions is improved, but inability to capture 3D information without minimum background brightness is a limitation

Engineering Contradiction:
Improvelow light operation capabilityVSAvoidinsufficient background light
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system implements multi-functionality by integrating three different depth sensing technologies (stereo vision, structured light, and time-of-flight) into a single headset. Each technology serves different lighting conditions, making the overall system universal and adaptable across all ambient light environments.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically switches between different imaging modes (stereo vision, structured light, time-of-flight) based on ambient light conditions. The controller monitors brightness levels and automatically selects the optimal imaging mode to maintain depth mapping accuracy across varying environmental conditions.

Inventive Principle:
Principle #15Dynamics

4Measurement precision

If traditional depth camera architectures are used, then 3D scene information capture is enabled, but device size and power consumption increase

Engineering Contradiction:
Improve3D scene information captureVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system dynamically activates only the necessary imaging mode based on ambient light conditions, avoiding continuous operation of all three technologies. This dynamic selection reduces power consumption while maintaining 3D scene information capture capability across different lighting environments.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system adjusts operational parameters such as ISO sensitivity, exposure time, and focal length to optimize performance for each imaging mode. By tuning these parameters efficiently, the system achieves accurate depth mapping with reduced energy expenditure compared to running all technologies at full power continuously.

Inventive Principle:
Principle #35Parameter changes

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 efficient capture of depth information in various dynamic light conditions, reducing the impact of background light and improving the accuracy of 3D scene mapping in augmented and virtual reality environments.

Implementation Method 1

a structured light source configured to project a known light pattern onto the local area and a camera configured to capture images of the local area including the projected light pattern

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

The one or more image capture devices include an infrared (IR)-sensitive camera configured to detect and capture images of infrared wavelengths

Methodology Applied
Scientific EffectInfrared radiation: Infrared Radiation

Data Source

PatentEP3371641B1Depth mapping with a head mounted display using stereo cameras and structured light
Publication Date: 2022.02.16 META PLATFORMS TECHNOLOGIES LLC
  • EP3371641B1 patent drawingFigure 1
  • EP3371641B1 patent drawingFigure 2
  • EP3371641B1 patent drawingFigure 3

AI summary

A an augmented reality (AR) headset includes a depth camera assembly that combines stereo imaging with structured light (SL) to generate depth information for an area of interest. The depth camera assembly includes at least two image capture devices and a SL illuminator and determines an imaging mode based on a signal to noise ratio or spatial variance of images captured by one or more of the cameras. Different imaging modes correspond to different operation of one or more image capture devices and the SL illuminator. The depth camera assembly includes different ranges of signal to noise ratios that each correspond to an imaging mode, and the depth camera assembly configures the image capture devices and the SL illuminator based on an imaging mode associated with a range of signal to noise ratios including the signal to noise ratio of a captured image.