Особенности построения цифровых моделей рельефа на основе метода космической радиолокационной интерферометрии

Basic stages of high and super-high resolution space borne synthetic aperture radar data interferometric processing are reviewed. The results of experimental research of the digital elevation maps accuracy with processing by different phase noise filtration algorithms and phase unwrapping methods are presented.Рассмотрены основные этапы интерферометрической обработки данных космических радиолокаторов с синтезированной апертурой высокого и сверхвысокого разрешения при построении цифровых моделей рельефа. Приведены результаты экспериментального исследования точности цифровых моделей рельефа при использовании различных алгоритмов фильтрации фазового шума и методов развертывания интерферометрической фазы

A regularized, model‐based approach to phase‐based conductivity mapping using MRI

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138865/1/mrm26590_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138865/2/mrm26590.pd

Three-Dimensional Nepal Earthquake Displacement Using Hybrid Genetic Algorithm Phase Unwrapping from Sentinel-1A Satellite

Introduction: Geophysicists had forewarned for decades that Nepal was exposed to a deadly earthquake, exceptionally despite its geology, urbanization and architecture. Gorkha earthquake is the most horrible natural disaster to crash into Nepal since the 1934 Nepal-Bihar earthquake. Gorkha earthquake occurred on April 25, 2015, at 11:56 NST and killed more than 10,000 people and injured more than 23,000 population. Objective: The main objective of this work is to utilize hybrid genetic algorithm for three-dimensional phase unwrapping of Nepal earthquake displacement using Sentinel-1A satellite. The three-dimensional best-path avoiding singularity loops (3DBPASL) algorithm was implemented to perform 3D Sentinel-1A satellite phase unwrapping. The hybrid genetic algorithm (HGA) was used to achieve 3DBPASL phase matching. Advancely, the errors in phase decorrelation were reduced by optimization of 3DBPASL using HGA. Results: The findings indicate a few cm of ground deformation and vertical northern of Kathmandu. Approximately, an area of 12,000 km2 has been drifted also the northern of Kathmandu. Further, each fringe of colour represents about 2.5 cm of deformation. The large amount of fringes indicates a large deformation pattern with ground motions of 3 m. Conclusion: In conclusion, HGA can be used to produce accurate 3D quake deformation using Sentinel-1A satellite

Phase unwrapping : geometric distortions correction on MRI

Magnetic Resonance Imaging has entered clinical practice about fifteen years ago, and has become one of the most widely used imaging modality. MRI suffers from important geometric distortions, leading to pixel shifts and intensity variations in the acquired images. Correction of these distortions is clearly required in stereotactic surgery using frame-based registrations or neuro-navigation. These distortions can be corrected using the phase of signal or image. However, as in Inverse Synthetic Aperture Radar (ISAR), the phase of the signal is obtained modulo 2 π. The goal of Phase unwrapping is to retrieve the initial phase of the signal. After a brief summary of related works and applications mainly using ISAR data, this paper presents a new algorithm for phase unwrapping. This algorithm is fast, robust to noise and takes into account the discontinuities of the acquired object. It is based upon the notion of homogeneous region. This homogeneity is defined by phase jumps and no parameters have to be determined a priori. Experiments on noisy phantoms exhibit good robustness to noise. An application to the correction of MRI of the head is presented.Les images du corps humain acquises par résonance magnétique sont une des modalités les plus utilisées à des fins cliniques depuis une quinzaine d'années. Elles souffrent cependant de distorsions géométriques importantes sous forme de décalages de pixels et de variations d'intensité. Ces distorsions doivent être corrigées pour utiliser ces imagés dans des applications de neuro-navigation ou de neuro-chirurgie stéréotaxiques. Une des solutions pour la correction exploite les images de phase issues de l'imageur. Cependant, comme en Interférométrie Radar à Ouverture Synthétique (ISAR), cette phase est codée modulo 2 π. Le déroulement de phase a pour objectif de retrouver la phase réelle du signal. Après un rapide bilan des outils existants, principalement dans le domaine ISAR, nous proposons dans cet article un algorithme de déroulement de phase original, rapide, robuste au bruit et qui prend en compte les discontinuités réelles de l'objet imagé. Il est basé sur la notion de région homogène du point de vue des sauts de phase et ne nécessite pas la détermination de paramètres. Les tests sur des fantômes bruités démontrent la bonne robustesse au bruit. Cet algorithme est ensuite utilisé pour la correction d'images IRM et illustre le bon déroulement de la phase