Composite SAR Image Azimuth Resolution Merging
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Solution Overview
Problem
Existing SAR image processing technologies face challenges in producing images that show distinct shadows of moving objects while preserving detail in stationary background clutter, as fine azimuth resolution images provide faint shadows of moving objects and coarse resolution images lack detail of stationary objects.
Innovation Solution
The solution involves using a combination of fine and coarse resolution image formers to produce SAR images, where a subset of phase histories is selected to create a coarse resolution image with darker shadows of moving objects, and the images are then combined to achieve a balance between shadow darkness and background detail, using a ratio of azimuth resolutions to determine the optimal pixel values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fine azimuth resolution SAR images are used, then detail of stationary background clutter is improved, but shadows of moving objects become faint
Solution Approach 1:
The patent combines fine resolution SAR images and coarse resolution SAR images to create a composite image. The fine resolution image provides detailed background clutter information, while the coarse resolution image provides dark shadows of moving objects. By merging these two image types through pixel-by-pixel combination based on azimuth resolution ratios, the system achieves both detailed background representation and distinct moving object shadows simultaneously.
2Object-affected harmful factors
If coarse azimuth resolution SAR images are used, then shadows of moving objects become darker, but detail of stationary background clutter is lost
Solution Approach 1:
The patent merges fine resolution and coarse resolution SAR images by combining their pixel values according to a predetermined ratio based on azimuth resolution. This allows the coarse resolution image's advantage of dark shadows to be integrated with the fine resolution image's advantage of detailed background clutter, achieving a composite image that possesses both characteristics.
Solution Approach 2:
The patent applies different resolution characteristics to different aspects of the image. The fine resolution component is used for stationary background clutter regions, while the coarse resolution component is used for moving object shadow regions. This local differentiation of resolution quality allows each region to be optimized for its specific detection requirements.
3Object-affected harmful factors
If aperture time is shortened to darken shadows of moving objects, then shadow darkness is improved, but detail of stationary background clutter deteriorates
Solution Approach 1:
The patent dynamically adjusts the effective aperture time for different image regions. By using a ratio of azimuth resolutions between fine and coarse images, the system effectively extends the aperture time for stationary background regions (preserving detail) while maintaining shorter aperture time effects for moving object regions (preserving shadow darkness). This dynamic adaptation resolves the contradiction between aperture time and image quality.
Data Source
AI summary
A synthetic aperture radar (SAR) image is produced by using all phase histories of a set of phase histories to produce a first pixel array having a first azimuth resolution, and using less than all phase histories of the set to produce a second pixel array having a second azimuth resolution that is coarser than the first azimuth resolution. The first and second pixel arrays are combined to produce a third pixel array defining a desired SAR image that shows distinct shadows of moving objects while preserving detail in stationary background clutter.