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The Applicability of Mathematical Morphology Algorithm for Tropical Cyclone Eye and Water Body Boundary Extraction in SAR Data

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The Applicability of Mathematical Morphology Algorithm for Tropical Cyclone Eye and Water Body Boundary Extraction in SAR Data The Applicability of Mathematical Morphology Algorithm for Tropical Cyclone Eye and Water Body Boundary Extraction in SAR Data By Ke Wang A thesis in fulfilment of the requirements for the degree of Master of Engineering Surveying and Geospatial Engineering School of Civil & Environmental Engineering Faculty of Engineering The University of New South Wales September 2014 PLEASE TYPE THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Fam ily name: Wang First name: Ke Other name/s: Isabella Abbreviation for degree as given in the University calendar: ME (Master of Engineering) School: School of Civil &Environmental Engineering (CVEN) Faculty: Faculty of Engineering Title: The applicability of mathematical morphology algorithm for tropical cyclone eye and water body boundary extraction in SAR data Abstract 350 words maximum: (PLEASE TYPE) Tropical cyclone (TC) and flooding are global catastrophes, devastating natural disasters. Synthetic aperture radar (SAR) satellite images present unique capabilities of cloud penetration, from signal response of sea/ground surface backscatter. The availability of high spatial resolution SAR satellite imagery shows potential for new metrological and environmental applications. This thesis presents two major case studies detailing efficient approaches in TC eye extraction and water body detection, using data from spaceborne Radarsat-1 , En vi sat ASAR and airborne Interferometric Synthetic Aperture Radar (IFSAR). In the case study of TCs, using the relationship between normalized radar cross section (NRCS) and backscatter for the roughness of sea surface, SAR images enable the measurement of the areas of TC eyes as an identifiable result. The size and shape of TC eyes strongly corresponds with its evolution and strength. It can play a vital role in monitoring and forecasting the behaviour of TCs by introducing mathematical morphology methods. Skeleton pruning based on discrete curve evolution (DCE) was used to ensure global and local preservation of the TC eye shape, by reducing redundant skeletons caused by speckle noise along the edges of the TC eye. These morphological-based analyses have been employed explicitly for six representative ocean SAR images with different TC patterns. The results demonstrate a high degree of agreement with the area of coverage derived from reference data based on NOAA's manual work. The second case study for water body detection involves pattern recognition with respect to digital image segmentation. Morphological watershed algorithm is applicable for image segmentation, albeit excessively sensitive to speckle noise in SAR images, leading to over-segmentation and thus a reduction in efficiency. This thesis presents a novel approach for water body extraction from SAR images by applying marker-controlled watershed combined with top-hat transformation. The purpose of this case study is to improve the efficiency of watershed techniques compared with Canny edge detection results for fine resolution I FAR images, and to yield an intuitive and well segmented image for mapping of water body boundaries. Declaration relating to disposition of project thesis/dissertation I hereby grant to the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University libraries in all forms of media, now or here after known , subject to the provisions of the Copyright Act 1968. I retain all property rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstracts International (this is applicable to doctoral theses only). r?~l.t?~! .~. O. ' '?. ··· ·· · ·· · ····· · ·· ~Signature · · ···· · · · · · · · · · · ··· Date The University recogn ises that there may be exceptional circumstances requiring restrictions on copying or conditions on use. Requests for restriction for a period of up to 2 years must be made in writing. Requests for a longer period of restriction may be considered in exceptional circumstances and re uire the a roval of the Dean of Graduate Research . FOR OFFICE USE ONLY Date of completion of requirements for Award: THIS SHEET IS TO BE GLUED TO THE INSIDE FRONT COVER OF THE THESIS COPYRIGHT STATEMENT 'I hereby grant the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstract International (this is applicable to doctoral theses only). I have either used no substantial portions of copyright material in my thesis or I have obtained permission to use copyright material; where permission has not been granted I have applied/will apply for a partial restriction of the digital copy of my thesis or dissertation.' Signed ····· ······· ··· ~ ······ · ·· · ·· · · · · · ·· ·· ···· ············· Date .... ........ ... .. .P~/p;;,./:k?J? ..................... ........ .. AUTHENTICITY STATEMENT 'I certify that the Library deposit digital copy is a direct equivalent of the final officially approved version of my thesis. No emendation of content has occurred and if there are any minor variations in formatting, they are the result of the conversion to digital format.' Signed ...... ................ ~ .. ... ..................... .. ..... Date ...................... .r:?.~/ ~. ~• ./ . .?.1.?.! .$.'......................... .. ORIGINALITY STATEMENT 'I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation and linguistic expression is acknowledged.' Signed .. ... .... ... .. .~ .. .... .. ... .. .. ...... .. .. .. Date ... .......... .... P.Y..'?.k/~ . ~5 .... .. ... .. .... .... .. Abstract Tropical cyclone (TC) and flooding are global catastrophes, devastating natural disasters. Synthetic aperture radar (SAR) satellite images present unique capabilities of cloud penetration, from signal response of sea/ground surface backscatter. The availability of high spatial resolution SAR satellite imagery shows potential for new metrological and environmental applications. This thesis presents two major case studies detailing efficient approaches in TC eye extraction and water body detection, using data from spaceborne Radarsat-1, Envisat ASAR and airborne Interferometric Synthetic Aperture Radar (IFSAR). In the case study of TCs, using the relationship between normalized radar cross section (NRCS) and backscatter for the roughness of sea surface, SAR images enable the measurement of the areas of TC eyes as an identifiable result. The size and shape of TC eyes strongly corresponds with its evolution and strength. It can play a vital role in monitoring and forecasting the behaviour of TCs by introducing mathematical morphology methods. Skeleton pruning based on discrete curve evolution (DCE) was used to ensure global and local preservation of the TC eye shape, by reducing redundant skeletons caused by speckle noise along the edges of the TC eye. These morphological-based analyses have been employed explicitly for six representative ocean SAR images with different TC patterns. The results demonstrate a high degree of agreement with the area of coverage derived from reference data based on NOAA’s manual work. The second case study for water body detection involves pattern recognition with respect to digital image segmentation. Morphological watershed algorithm is applicable for image segmentation, albeit excessively sensitive to speckle noise in SAR images, leading to over- segmentation and thus a reduction in efficiency. This thesis presents a novel approach for water body extraction from SAR images by applying marker-controlled watershed combined with top- hat transformation. The purpose of this case study is to improve the efficiency of watershed i techniques compared with Canny edge detection results for fine resolution IFAR images, and to yield an intuitive and well segmented image for mapping of water body boundaries. ii Acknowledgement Foremost, I would like to express my deepest thanks to my supervisors, Professor John C. Trinder, he has been a mentor to me in a way. This spirit of mentorship has pervaded every step of my research, and I would like to thank him for offering thorough and excellent feedback on every version of this thesis even during his holiday. Literally, I am truly grateful for his selfless dedication to both my personal and academic development, as I consider
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