초록 ▼

An improved method is provided for phase unwrapping in coherent imaging systems which use two complex images to form an interferogram. In the improved method, the interferogram of phase differences is divided into a relatively large plurality of transform blocks, wherein each transform block compris

An improved method is provided for phase unwrapping in coherent imaging systems which use two complex images to form an interferogram. In the improved method, the interferogram of phase differences is divided into a relatively large plurality of transform blocks, wherein each transform block comprises a matrix of o.times.p data samples, with o and p=2.sup.n +1, and n being an integer greater than 2. Further, adjacent transform blocks are preferably defined to partially overlap. The wrapped phase values of adjacent data samples within each transform block are then compared and if the difference therebetween exceeds a predetermined value, the entire block of data samples may be discarded for further use. Data samples of the retained transform blocks are then unwrapped to obtain phase values via an unweighted, least-squares technique implemented by Fast Fourier Transform. Using a known height value corresponding with a single data sample, an integration constant can be determined for a corresponding first transform block. Path-following may then be used to determine an integration constant for the other retained transform blocks. The phase values and integration constants may then be employed to determine height values for the interferogram. The disclosed method yields enhanced accuracy with reduced computational burden.

대표청구항 ▼

[ What is claimed is:] [1.] A method for determining height information from an interferogram of complex data samples generated from two complex images of an imaged terrain region acquired by an interferometric synthetic aperture radar system, wherein each of said complex data samples comprises a wr

[ What is claimed is:] [1.] A method for determining height information from an interferogram of complex data samples generated from two complex images of an imaged terrain region acquired by an interferometric synthetic aperture radar system, wherein each of said complex data samples comprises a wrapped phase value, comprising:dividing said interferogram into a plurality of transform blocks, wherein each transform block comprises a plurality of complex data samples, and wherein each of said transform blocks partially overlaps at least one adjacent, block in a corresponding overlapping region;determining a difference value between the wrapped phase values of each set of adjacent complex data samples comprising a given transform block;comparing each said difference value to a predetermined value, wherein all complex data samples comprising a given transform block are discarded when any single difference value corresponding with the transform block exceeds said predetermined value, and wherein all complex data samples comprising a transform block are retained when all difference values corresponding with the transform block are less than the predetermined value;unwrapping a phase difference value for each of a plurality of retained data samples comprising an overlapping region corresponding with first and second transform blocks; andusing a known height value corresponding with one of said plurality of complex data samples comprising said first transform block to establish an integration constant for the first transform block; andemploying said integration constant for said first transform block and said unwrapped phase difference values to determine an integration constant for at least said second transform block.