Passive 3D Depth Sensing via Filter Mask Blur Analysis
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Solution Overview
Problem
Conventional active techniques for three-dimensional image sensing in portable devices, such as smartphones, face limitations in power consumption, spatial constraints, and difficulty in dynamic calibration, especially in varying ambient lighting conditions, making them unreliable for advanced features like depth mapping and focus automation.
Innovation Solution
A passive three-dimensional image sensing method using a filter mask with normal and reference imaging bandpass regions, integrated with a lens assembly, where light rays pass through different regions with distinct focal lengths, allowing for the detection of blurring between images to determine object distance, and enhanced with additional reference illumination for improved detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active techniques (time-of-flight, triangulation) are used for depth sensing, then depth measurement capability is achieved, but power consumption increases and spatial requirements expand
Solution Approach 1:
The patent replaces active mechanical/electronic depth sensing systems (time-of-flight sensors, structured light projectors) with a passive optical system that uses a filter mask and conventional imaging sensor. The system substitutes complex active sensing mechanics with passive optical filtering and image processing, eliminating the need for additional illumination sources and complex sensing hardware while maintaining depth measurement capability through focus blur analysis
Solution Approach 2:
The patent extracts and removes the active illumination components and complex sensing hardware from the depth sensing system. By taking out the time-of-flight lasers, structured light projectors, and specialized sensors, the invention reduces power consumption and spatial requirements while retaining essential depth measurement functionality through passive optical means
2Measurement precision
If active techniques (time-of-flight, triangulation) are used for depth sensing, then depth measurement capability is achieved, but device size and spatial constraints are exceeded
Solution Approach 1:
The patent merges the depth sensing functionality with the existing conventional imaging system by integrating a filter mask into the lens assembly. Instead of adding separate active sensing components that would increase device size, the invention combines depth sensing capabilities with the existing camera optics and sensor, allowing both photography and depth mapping to share the same optical path and hardware resources
Solution Approach 2:
The patent makes the conventional imaging system multi-functional by enabling it to perform both standard photography and passive depth sensing simultaneously. The filter mask and imaging sensor serve dual purposes: capturing visible light images and capturing depth information through focus blur analysis, thereby eliminating the need for dedicated active sensing hardware and reducing overall device spatial requirements
3Device complexity
If conventional imaging systems are used without specialized illumination, then device simplicity is maintained, but depth information accuracy is insufficient
Solution Approach 1:
The patent introduces a filter mask as an intermediary component between the lens and the sensor. This filter mask selectively transmits different wavelengths of light to create controlled focus blur effects that encode depth information. The filter mask acts as a mediator that transforms ordinary light from the scene into depth-encoded optical signals without requiring complex active illumination, thereby maintaining system simplicity while improving depth measurement accuracy
Solution Approach 2:
The patent changes the optical parameters of the imaging system by introducing wavelength-selective filtering through the filter mask. By manipulating the focal properties of different wavelength bands and analyzing the resulting focus blur variations, the system extracts depth information from passive light without requiring active illumination. This parameter-based approach maintains hardware simplicity while enhancing depth sensing capability
4Use of energy by moving object
If passive image blurring is used for depth sensing, then power consumption is reduced and spatial constraints are met, but measurement reliability in varying lighting conditions deteriorates
Solution Approach 1:
The patent segments the optical spectrum into multiple wavelength bands using the filter mask, with each band providing independent depth information through focus blur analysis. By dividing the light spectrum into separate channels (e.g., different color bands), the system can selectively process wavelengths that are least affected by ambient lighting variations, thereby maintaining measurement reliability while keeping power consumption low and spatial requirements minimal
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 efficient and accurate depth mapping in portable devices without the need for active illumination, overcoming power and spatial constraints, and providing reliable depth information for advanced imaging features like auto-focus and 3D photography.
Implementation Method 1
The NIB and RIB regions of the filter mask are optically distinguishable and are configured in the lens assembly to have different focal lengths and/or different focal paths
Implementation Method 2
As light rays from a scene object pass through the different regions of the filter mask, a sensor can detect first and second images responsive to those light rays focused through the NIB region and the RIB region
Data Source
AI summary
Techniques are described for passive three-dimensional image sensing based on referential image blurring. For example, a filter mask is integrated with a lens assembly to provide one or more normal imaging bandpass (NIB) regions and one or more reference imaging bandpass (RIB) regions, the regions being optically distinguishable and corresponding to different focal lengths and/or different focal paths. As light rays from a scene object pass through the different regions of the filter mask, a sensor can detect first and second images responsive to those light rays focused through the NIB region and the RIB region, respectively (according to their respective focal lengths and/or respective focal paths). An amount of blurring between the images can be measured and correlated to an object distance for the scene object. Some embodiments project additional reference illumination to enhance blurring detection in the form of reference illumination flooding and/or spotted illumination.