Long-Range Iris Acquisition Using Dynamic Pan-Tilt Tracking
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Solution Overview
Problem
Iris pattern-based biometric systems face challenges in acquiring well-focused eye images from stand-off distances due to limited capture volumes and the need for subject cooperation, with existing systems either requiring fixed positions or increased hardware costs for larger capture volumes.
Innovation Solution
A novel long-range iris acquisition system using commercial off-the-shelf equipment, incorporating a single camera with pan/tilt capabilities and continuous IR illumination, capable of capturing high-resolution iris images from up to 12 meters with a single camera setup, and tracking mobile subjects at walking speeds, while maintaining low costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed focus system with narrow depth of field is used to increase stand-off distance, then subject cooperation is reduced, but capture volume remains limited and acquisition fails when iris is not within the small capture volume
Solution Approach 1:
The system employs a movable capture volume that dynamically adjusts its position and size based on detected subject characteristics. The capture volume is not fixed in space but can be repositioned along the optical axis and laterally to track and accommodate subjects of varying heights and positions, thereby increasing the effective capture volume while maintaining the benefits of fixed-focus optics.
2Volume of stationary object
If multiple cameras are stacked to increase capture volume height, then subjects of different heights can be captured, but hardware cost and system complexity increase
Solution Approach 1:
Instead of using multiple fixed cameras stacked vertically, the invention uses a single movable capture volume that can dynamically reposition itself to capture subjects of different heights. This dynamic approach achieves the same functional result as multiple cameras but with simpler hardware and lower system complexity.
3Device complexity
If a single camera setup is used to reduce cost, then system complexity is reduced, but capture volume and stand-off distance are limited compared to multi-camera systems
Solution Approach 1:
The patent employs a movable capture volume that can dynamically adjust its position and orientation to track subjects. This dynamic capability allows a single camera system to achieve the functional equivalent of multiple fixed cameras, expanding the effective capture volume without increasing hardware complexity or cost.
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 system achieves high-resolution iris imaging from greater distances than prior art, with improved subject tracking and reduced cooperation requirements, maintaining image quality and reducing system costs through the use of standard components.
Implementation Method 1
sufficient near infra-red (NIR) illumination must be provided for acquisition
Data Source
AI summary
Described is a system which is capable of capturing images of the iris up to distances of 11 meters with a resolution of 150-200 pixels across the diameter. The system incorporates velocity estimation and focus tracking modules such that that images may be acquired from moving subjects.