TOF Depth Camera Patterned Light Generator Noise Reduction
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Solution Overview
Problem
Time-of-flight (TOF) depth cameras face challenges in obtaining high precision depth images in noisy light environments due to non-uniform illumination, which reduces image resolution and accuracy.
Innovation Solution
Incorporating a patterned light generator that creates a light pattern with high intensity spots and surrounding low-intensity regions, combined with a filter unit that reduces noise light using a band pass filter and optical modulator, to enhance the signal-to-noise ratio and improve depth image measurement precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If uniform illumination is used in TOF depth camera, then the field of view is fully covered, but the signal-to-noise ratio decreases and measurement precision deteriorates
Solution Approach 1:
The patent applies local quality by using a patterned light generator to create non-uniform illumination with high-intensity spots at specific locations rather than uniform illumination across the entire field of view. This concentrates light energy where needed to improve signal-to-noise ratio and measurement precision in critical regions, while accepting lower illumination in other areas.
2Measurement precision
If patterned light with high intensity spots is used, then the signal-to-noise ratio is improved, but the illumination uniformity deteriorates
Solution Approach 1:
The patterned light generator creates localized high-intensity regions (spots) in the illumination pattern, concentrating light energy in specific areas to enhance the signal-to-noise ratio for depth measurement in those regions, deliberately sacrificing overall illumination uniformity.
3Measurement precision
If additional optical components (patterned light generator, filter device) are added, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent segments the optical system into distinct functional modules: a light source, a patterned light generator (such as a diffractive optical element or micro-lens array), a filter device (band pass filter and optical modulator), and an image sensor. This segmentation allows each component to be optimized for its specific function while working together to achieve high measurement precision.
Solution Approach 2:
The patent introduces intermediary components between the light source and image sensor: the patterned light generator acts as an intermediary to create the desired illumination pattern, and the filter device serves as an intermediary to remove noise light. These intermediaries enable precise control over the light reaching the sensor, improving measurement precision despite increased system complexity.
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
The solution enables high precision depth image measurement even in noisy light conditions by increasing the signal-to-noise ratio, allowing for clear detection of depth information and improved image resolution through the use of a patterned light and noise reduction techniques.
Implementation Method 1
The changing the light emitted from the light source into the patterned light may include diffracting the light using a diffractive optical element
Implementation Method 2
The changing the light emitted from the light source into the patterned light may include refracting the light using a refractive optical element
Implementation Method 3
The filter unit may include a band pass filter
Implementation Method 4
The filter unit may include an optical modulator
Implementation Method 5
a depth image is extracted based on a time-of-flight (TOF), that is, the time required for the IR ray to return to a camera after the IR ray is reflected by the object
Data Source
AI summary
Provided are a depth camera and methods of measuring a depth image by using the depth camera. The depth camera is a time-of-flight (TOF) depth camera including: an illumination device that illuminates a patterned light to an object; a filter unit that reduces noise light included in light reflected by the object; and an image sensor that provides a depth image of the object by receiving light that enters through the filter unit. The illumination device includes: a light source; and a patterned light generator that changes the light emitted from the light source into the patterned light. The filter unit includes a band pass filter and an optical modulator. The patterned light generator may be a diffractive optical element or a refractive optical element.