Decentered Lens Distortion for Point Source Detection in Fog
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Solution Overview
Problem
Enhanced vision systems (EVSs) face challenges in detecting airport approach lights in foggy weather, particularly with LED approach lights, due to low contrast and high background noise, which affects the signal-to-background ratio and makes it difficult to distinguish point source signals in daytime fog environments.
Innovation Solution
The use of a decentered lens with distortion, such as a high barrel/fisheye type, increases pixel density in the region of interest, improving contrast and signal-to-noise ratio for point source detection by creating a smaller instantaneous field of view in the central region and a larger field of view in peripheral regions, allowing for effective detection of approach lights in foggy conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard lens with uniform field of view is used, then the entire scene is captured, but the pixel density in the region of interest is insufficient leading to low contrast and poor signal-to-noise ratio
Solution Approach 1:
The patent applies a decentered lens with distortion that creates non-uniform pixel density across the field of view. Specifically, the lens is positioned off-center relative to the sensor, creating a region of interest with higher pixel density for detecting point source objects while maintaining adequate coverage of the surrounding scene. This local quality enhancement allows the system to prioritize detection precision in critical areas without completely sacrificing overall scene coverage.
Solution Approach 2:
The patent introduces asymmetry by deliberately decentering the lens relative to the sensor and using a distorted lens design. This asymmetric configuration creates a non-uniform mapping between the object space and sensor space, resulting in higher pixel density in the region of interest. The asymmetric approach allows the system to optimize for point source detection in specific areas while maintaining broader scene awareness.
2Measurement precision
If pixel density is increased in the region of interest to improve detection, then contrast and signal-to-noise ratio improve, but the field of view in peripheral regions is reduced
Solution Approach 1:
The decentered lens creates a localized region of high pixel density around the region of interest, improving signal-to-noise ratio for point source detection in that specific area. The peripheral regions maintain sufficient but lower pixel density, preserving adequate field of view coverage for contextual awareness without compromising overall system versatility.
3Measurement precision
If a decentered lens with distortion is used to increase pixel density in the region of interest, then point source detection is improved, but image distortion increases requiring correction
Solution Approach 1:
The patent applies distortion correction as a preliminary processing step before point source detection. By pre-correcting or pre-compensating for the lens distortion, the system simplifies subsequent detection algorithms. The correction parameters can be predetermined based on the known lens characteristics, reducing real-time processing complexity while maintaining detection precision.
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 enhances the detection of point source objects like approach lights by improving contrast and signal-to-noise ratio, enabling better visibility of LED approach lights in foggy conditions, even when they appear as single pixels, thereby reducing system noise and improving pilot visibility.
Implementation Method 1
The use of a decentered lens with distortion, such as a high barrel/fisheye type, increases pixel density in the region of interest, improving contrast and signal-to-noise ratio for point source detection by creating a smaller instantaneous field of view in the central region
Data Source
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AI summary
A system and method. The system may include a display, a lens having distortion, an image generator, and a processor. The lens may be configured to focus light received from an environment. The image generator may be configured to receive the light from the lens and output a stream of images as image data, wherein each of the stream of images is distorted. The processor may be configured to: receive the image data from the image generator; detect a point source object in the stream of images of the image data; enhance the point source object in the stream of images of the image data; undistort the stream of images of the image data having an enhanced point source object; and output a stream of undistorted images as undistorted image data to the display.