Contactless Fingerprint Capture Using Rotating Object-Plane Imaging
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Solution Overview
Problem
Existing contactless biometric fingerprint capturing methods require multiple image-capture devices, making systems expensive, bulky, and complex due to the need for simultaneous two-dimensional capturing from different angles.
Innovation Solution
A method involving successive two-dimensional image acquisition with orientation modification of the object plane by rotating about a pivot axis, merging these images, and associating three-dimensional location information to generate a three-dimensional model of the hand surface, using a single imaging device with a rotatable optical element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple image-capture devices are used to simultaneously capture two-dimensional images from different angles, then the biometric fingerprint capture accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent employs a rotatable optical element that dynamically changes the imaging angle between successive captures. Instead of using multiple static cameras, a single camera captures images at different angles by rotating the optical element, thereby reducing device complexity while maintaining the ability to capture fingerprint details from multiple perspectives
Solution Approach 2:
The patent transitions from simultaneous multi-angle capture (spatial dimension) to sequential multi-angle capture with rotation (temporal dimension). By capturing images at different time points with rotated optical elements and merging them, the system achieves three-dimensional modeling capability without requiring multiple cameras positioned in space
2Measurement precision
If multiple image-capture devices are used to simultaneously capture two-dimensional images from different angles, then the biometric fingerprint capture accuracy is improved, but the system cost increases
Solution Approach 1:
The patent merges multiple two-dimensional images captured at different angles into a single three-dimensional model. This image merging process combines the information from successive captures to create a comprehensive biometric representation, eliminating the need for expensive multiple-camera systems while maintaining high capture accuracy
Solution Approach 2:
The patent creates a three-dimensional synthetic copy of the fingerprint surface from multiple two-dimensional image captures. This synthetic 3D model serves as a comprehensive biometric identifier, replacing the need for complex multi-camera hardware while achieving superior measurement precision
3Area of stationary object
If the object plane is modified by rotating about a pivot axis between successive image acquisitions, then the image surface area coverage is improved, but the system complexity increases
Solution Approach 1:
The patent introduces dynamic rotation of the optical element about a pivot axis to change the imaging angle between successive captures. This dynamic adjustment allows the single camera to cover a larger surface area of the hand by viewing it from different angles, achieving enhanced area coverage without adding multiple cameras
Solution Approach 2:
The patent segments the image capture process into multiple successive captures at different rotated angles. Each capture covers a portion of the hand surface, and the combination of these segmented captures provides comprehensive surface area coverage that would require multiple simultaneous cameras
Data Source
AI summary
A method for contactlessly capturing a biometric fingerprint of part of a hand of a user in an acquisition volume, the method including successively acquiring at least two two-dimensional images of the part of the hand, involving, between said successive acquisitions, modifying the orientation of an object plane by rotating about a pivot axis, the at least two images comprising imaged points of the part of the hand common to said at least two acquisitions, the object plane being modified as a function of a modification of a given current plane for positioning the part of the hand, corresponding to the average current plane in which said part of the hand is located, for each two-dimensional image acquisition, and merging the acquired two-dimensional images of a surface of the part of the hand that is to be depicted.