Defocusing-Based 3D Imaging Camera Pose Extraction
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Solution Overview
Problem
Current 3-D imaging methods are limited by inaccurate techniques for determining camera pose, resulting in insufficient resolution for applications like dental imaging, which requires higher precision and accuracy, especially when imaging objects with few detectable corners.
Innovation Solution
A method and device using defocusing techniques to capture and match defocused images from different camera poses, allowing for the extraction of 3-D locations of object features and calculation of camera pose changes, enabling the construction of high-resolution 3-D images by overlaying defocused images from projected marker patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current 3-D imaging methods use mono or stereo features to find camera pose, then the process is simple, but the resolution is limited to approximately 200 microns
Solution Approach 1:
The patent changes the fundamental parameter used for measurement from 2-D feature locations to 3-D feature locations derived from defocusing patterns. By utilizing the depth information encoded in defocus blur, the system achieves sub-200-micron resolution (down to 25-50 microns for dental imaging) without adding complex hardware, only requiring standard camera equipment with controlled defocusing
Solution Approach 2:
The patent introduces defocusing as an intermediary mechanism to extract 3-D location information. The defocus pattern acts as a mediator that encodes depth information in the 2-D image plane, allowing the system to recover 3-D camera pose and object geometry without requiring complex stereo vision or active range finding hardware
2Reliability
If current techniques image objects with few detectable corners, then the process remains straightforward, but large error levels are produced
Solution Approach 1:
Instead of requiring sharp, well-defined corners and edges for feature detection, the patent inverts the approach by intentionally introducing blur through defocusing. The blur pattern itself becomes the feature, allowing reliable measurement even on surfaces with few or no detectable corners. The defocus magnitude and pattern provide robust 3-D location information independent of surface texture or corner presence
Solution Approach 2:
The patent changes the measurement parameter from 2-D feature coordinates to 3-D feature coordinates derived from defocus analysis. This parameter transformation enables accurate camera pose determination even when traditional 2-D feature detection fails, as the 3-D location information is encoded in the defocus pattern rather than requiring sharp corner detection
3Measurement precision
If accurate 3-D location extraction is achieved through defocusing, then high-resolution imaging is possible, but the device complexity increases
Solution Approach 1:
The patent makes the standard camera lens serve multiple functions: it acts as both the imaging lens for capturing 2-D images and the defocusing mechanism for encoding 3-D information. By controlling the object distance relative to the focal plane, the same lens produces both in-focus and defocused images that contain 3-D location information, eliminating the need for separate range-finding hardware
Solution Approach 2:
The imaging system performs its own 3-D measurement function using its existing optical components. The camera's lens and sensor, already present for 2-D imaging, are utilized to generate defocus patterns that encode 3-D information. The system is self-sufficient, requiring no external active illuminators, range finders, or specialized sensors beyond the standard camera
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 achieves high-resolution 3-D imaging with effectively unlimited resolution, overcoming the limitations of existing methods by accurately determining camera pose and constructing detailed 3-D images, suitable for applications requiring precision beyond the 200-micron resolution range.
Implementation Method 1
A lens is obstructed by a mask having at least one set of off-axis apertures for producing a plurality of defocused images of an object substantially simultaneously
Data Source
AI summary
A method and device for high-resolution three-dimensional (3-D) imaging which obtains camera pose using defocusing is disclosed. The device comprises a lens obstructed by a mask having two sets of apertures. The first set of apertures produces a plurality of defocused images of the object, which are used to obtain camera pose. The second set of optical filters produces a plurality of defocused images of a projected pattern of markers on the object. The images produced by the second set of apertures are differentiable from the images used to determine pose, and are used to construct a detailed 3-D image of the object. Using the known change in camera pose between captured images, the 3-D images produced can be overlaid to produce a high-resolution 3-D image of the object.