Method and system for forming very low noise imagery using pixel classification
First Claim
1. A method for generating images from projection data comprising:
- inputting from at least one data receiving element first values representing correlated positional and recorded data;
each of said first values forming a point in an array of N aperture positions;
forming an image by processing the projection data utilizing a pixel characterization imaging subsystem that combines the positional and recorded data to form the SAR imagery utilizing one of a back-projection algorithm or range migration algorithm;
integrating positional and recorded data from many aperture positions, comprising;
forming the complete aperture for SAR image formation comprising collecting the return radar data, the coordinates of the receiver, and the coordinates of the transmitter for each position along the complete aperture of N positions;
forming an imaging grid comprising M image pixels wherein each pixel Pi in the imaging grid is located at coordinate (xp(i),yp(i), zp(i));
selecting and removing a substantial number of aperture positions from the aperture of N positions to form a sparse aperture array;
forming a preliminary image using the sparse aperature array;
repeating the selecting and removing step and forming a preliminary image step for L iterations;
classifying each pixel in the image into either target class based on the statistical distribution of its amplitude across L iterations;
whereby if an image pixel is classified so as to be associated with a physical object, its value is computed from its statistics;
otherwise, the pixel is assumed to come from a non-physical object and is given the value of zero.
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Abstract
A method and system for generating images from projection data comprising inputting first values representing correlated positional and recorded data; forming an image by processing the projection data utilizing a pixel characterization imaging subsystem to form the SAR imagery utilizing one of a back-projection algorithm or range migration algorithm; integrating positional and recorded data from many aperture positions, comprising: forming the complete aperture A0 comprising collecting the return radar data, the coordinates of the receiver, and the coordinates of the transmitter for each position k along the aperture of N positions; forming an imaging grid comprising M image pixels; selecting and removing a substantial number of aperture positions to form a sparse aperture Aifor L iterations; classifying each pixel in the image into target class based on the statistical distribution of its amplitude across L iterations; otherwise, the pixel is given the value of zero.
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Citations
20 Claims
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1. A method for generating images from projection data comprising:
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inputting from at least one data receiving element first values representing correlated positional and recorded data;
each of said first values forming a point in an array of N aperture positions;forming an image by processing the projection data utilizing a pixel characterization imaging subsystem that combines the positional and recorded data to form the SAR imagery utilizing one of a back-projection algorithm or range migration algorithm; integrating positional and recorded data from many aperture positions, comprising; forming the complete aperture for SAR image formation comprising collecting the return radar data, the coordinates of the receiver, and the coordinates of the transmitter for each position along the complete aperture of N positions; forming an imaging grid comprising M image pixels wherein each pixel Pi in the imaging grid is located at coordinate (xp(i),yp(i), zp(i)); selecting and removing a substantial number of aperture positions from the aperture of N positions to form a sparse aperture array; forming a preliminary image using the sparse aperature array; repeating the selecting and removing step and forming a preliminary image step for L iterations; classifying each pixel in the image into either target class based on the statistical distribution of its amplitude across L iterations; whereby if an image pixel is classified so as to be associated with a physical object, its value is computed from its statistics;
otherwise, the pixel is assumed to come from a non-physical object and is given the value of zero.- View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for generating images of a scanned area from projection data comprising:
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inputting scanned data having first values representing correlated positional and recorded data;
each of said first values forming an aperture position;forming an initial aperture array consisting of N aperture positions, each aperture position comprising correlated positional and recorded data; forming an imaging grid comprising image pixel locations; forming an initial image by generating backprojection values for each pixel location by coherently summing the scanned data collected at each aperture position into the initial aperture array of positions; for a series of iterations, generating a series of secondary aperture arrays using at least one processor by using different subsets of aperture positions from the initial aperture array for each iteration; forming pixels for the imaging grid from the secondary aperture arrays; comparing the values of the pixels generated from the secondary aperture arrays and classifying each pixel as either target data or that originating from noise or a sidelobe based upon the magnitude and frequency of occurrence during the iterations; forming the image whereby the value of each pixel is examined across L iterations to determine whether or not the pixel represents a physical object. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A system for generating images from projection data comprising:
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at least one processor for processing image information;
the at least one processor having an input for inputting scanned data having first values representing correlated positional and recorded data;
each of said first values forming a point in an array of aperture positions;the at least one processor operating to perform the following steps; (a) forming an initial aperture array consisting of N aperture positions, each aperture position comprising radar receiving position information, radar transmitting information, and the data record that was measured at the target location; (b) forming an imaging grid comprising image pixel locations; (c) forming an initial image using backprojection values for each pixel location by coherently summing the scanned data collected at each data point into the initial aperture array of aperture positions; (d) for a series of iterations, generating a series of secondary aperture arrays using at least one processor by using different subsets of aperture positions from the initial aperture array for each iteration; (e) comparing the values of the pixels generated from the secondary aperture arrays and classifying each pixel as either target data or that originating from noise or a sidelobe based upon the magnitude and frequency of occurrence during the iterations; (f) forming the image whereby the value of each pixel is examined across L iterations to determine whether or not the pixel represents a physical object. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification