Depth Camera Light Leakage Avoidance via Shutter Masking
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Solution Overview
Problem
Depth sensing devices, particularly in HMD devices, face inaccuracies due to light leakage caused by protective optical components, which redirect a portion of the emitted light back to the camera, leading to incorrect depth measurements.
Innovation Solution
The depth sensing device identifies and excludes the light leakage by generating a light leakage mask, which subtracts the pixel values corresponding to the redirected light, ensuring accurate depth measurements by considering only the light reflected from the environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a protective optical component is added to protect the depth camera, then the camera is protected from damage, but light leakage occurs causing inaccurate depth measurements
Solution Approach 1:
The patent segments the light detection process into two distinct portions: leaked light detection and reflected light detection. By using the shutter to separately capture images during different time windows (first time window for leaked light, second time window for reflected light), the system divides the detection function to eliminate the harmful effect of the optical component while maintaining protection.
Solution Approach 2:
The patent performs preliminary action by capturing the leaked light image first (during the first time window) before capturing the reflected light image (during the second time window). The leaked light image is then used to generate a mask that is subtracted from the reflected light image, thereby preliminarily eliminating the harmful effect before final depth calculation.
2Illumination intensity
If the shutter captures all emitted light, then the imaging sensor receives sufficient light for detection, but the redirected light causes depth errors
Solution Approach 1:
The patent employs periodic action by using the shutter to open and close at specific time intervals, creating distinct time windows for capturing different light portions. The shutter opens during the first time window to capture leaked light, then opens during the second time window to capture reflected light, thereby periodically sampling light at different stages to separate harmful from useful signals.
Solution Approach 2:
The patent extracts the harmful leaked light portion from the total light signal by capturing it separately during the first time window. This extracted leaked light information is then used to create a mask that removes the harmful portion from the reflected light image, leaving only the useful reflected light data for accurate depth measurement.
3Measurement precision
If the light leakage mask is generated and subtracted from the recorded image, then depth measurement accuracy is improved, but the processing complexity increases
Solution Approach 1:
The patent applies self-service by using the imaging sensor and processor within the depth sensing device itself to capture, process, and eliminate the leaked light. The device's own components are utilized to generate the light leakage mask and subtract it from the recorded image, thereby self-correcting the measurement error without requiring external intervention or complex additional hardware.
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 solution effectively reduces depth errors by isolating the light leakage, allowing for precise depth mapping and accurate 3D reconstruction, applicable to various depth sensing systems including pulse-based and phase-based ToF cameras and structured light stereo matching systems.
Implementation Method 1
The time taken for the light to travel from the light source and to reflect back from an object to the ToF camera is converted, based on the known speed of light, into a depth measurement
Implementation Method 2
a ToF camera captures the light after it reflects off nearby objects
Data Source
AI summary
Disclosed are a device and a method of depth sensing that handle light leakage issues. In some embodiments, the depth sensing device includes a light emitter that illuminates an environment of the depth sensing device. The device identifies a first portion of the emitted light that is prevented from reaching the environment of the device due to being redirected by an optical component located in proximity to the light emitter. An imaging sensor of the device detects a second portion of the emitted light that reaches and is reflected by a surface in the environment of the device other than a surface of the optical component. The device generates, based on the second portion of the emitted light, a depth map that includes a plurality of values corresponding to distances relative to the device, wherein said generating excludes from consideration the identified first portion of the emitted light.