Search

We propose a combined minimum discontinuity phase unwrapping algorithm based on clusters. The wrapped phase image is tessellated into small regular blocks by the main node according to the com - puting resources and then sent to the idle computing nodes. During the unwrapping process of single block, the wrapped phase quality map is firstly computed and the wrapped phase image is partitioned into high and low quality areas; then the quality-guided and minimum discontinuity combined phase unwrapping algorithm is performed to get the initial unwrapped result. After the local unwrapping process is finished, the initial unwrapped result and the region partition result are sent to the main node. When all the blocked phases are unwrapped, the main node performs the minimum discontinuity optimization process on the bor- der of different blocks and the adjacent low quality areas to get the final unwrapped result. Tests performed on the simulated and the real InSAS (interferometric synthetic aperture sonar) interferograms based on clus- ters confirm the validity and efficiency of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Phase unwrapping is one of the key processing steps during reconstruction the digital elevation model from the signal of interferometric synthetic aperture radar(InSAR) or interferometric synthetic aperture sonar(InSAS). In order to solve the problem of low unwrapping efficiency with large interferogram, we propose a blocked minimum discontinuity phase unwrapping algorithm in shared memory environment. The whole phase quality map is computed firstly through multi-cores of CPU, then wrapped phase image and phase quality map are tessellated into small regular blocks, which are unwrapped by the quality guided and minimum discontinuity optimization method simultaneously. In the end, the minimum discontinuity optimization process is performed again on the border of different blocks and the low quality areas located on the border to get the final merged unwrapped result in the main thread. Tests performed on the simulated and real InSAS interferogram show that the speed up reaches 3.98 and 2.26 respectively. [ABSTRACT FROM AUTHOR]

We propose a non-recursive minimum discontinuity phase unwrapping algorithm for im­proved efficiency. After analyzing the principles of minimum discontinuity phase unwrapping algo­rithm* a stack is used to store the intermediate results during edge spreading and circle canceling processes and thena non-recursive algorithm for phase unwrapping is implemented. The new algorithm was combined with the quantized quality-guided phase unwrapping algorithm, which enhances the un­wrapping efficiency by restricting the optimization area. Unwrapping tests performed on InSAR and InSAS interferograms show that the proposed method maintains high quality unwrapping results and greatly improves efficiency. [ABSTRACT FROM AUTHOR]

We proposed a parallel quality-guided phase unwrapping algorithm in shared memory environment. The intrinsic relationship between the neighboring phase points about quality value computing is analyzed firstly, and then the row and column arrays are used to store the intermediate results in order to eliminate the repeated computation of gradient. The computing task is allocated by row, which can simplify the computing of row and column gradient mean values. Finally, the allocation of computing task is realized using OpenMP instructions, and the quality map is computed in parallel. The inherent parallelism of quality guided process is also analyzed in-depth, but subject to the repetitive thread startup and exit overhead, it is difficult to reflect the advantage of speed. Unwrapping tests performed on InSAR and InSAS interferogram show that the proposed method greatly improves the efficiency of phase unwrapping, and provides a foundation for improving the solution precision under real-time conditions. [ABSTRACT FROM AUTHOR]

We propose a combined phase unwrapping algorithm using region partitioning. The wrapped phase image is partitioned into high and low quality areas according to its quality map- and a quality guided algorithm is performed to gel the initial unwrapped result. A quality guided strategy is adopted to identify low quality areas- and each low quality area is stored separately. The low quality areas are optimized by a minimum discontinuity phase unwrapping algorithm one by one. and then the final unwrapped result is obtained. An unwrapping test performed on an InSAR interferogram shows that the proposed algorithm is more efficient than the minimum discontinuity phase unwrapping algorithm, and the unwrapped result was more accurate than results obatained from a quality guided algorithm. [ABSTRACT FROM AUTHOR]