Acoustic detection and bottom classification  

Zygmunt Klusek  

•  detection, recognition and mapping of dumped munitions fusing the acoustic, magnetic and visual imaging methods

•  technology development in improving the acoustical imaging of buried ammunition

•  arrangement of the data base of all collected information for integrated system that includes geographical coordinates and the precise characteristics of the targets.

GOALS  OF  THE  PROJECT  (SELECTED  ISSUES)    

• INTRODUCTION

• ACOUSTIC METHODS/MEASUREMENT SETUP SIDE SCAN SONAR MULTIBEAM SONAR

NEW TECHNOLOGIES

•  COMPLEMENTARY METHODS – MAGNETOMETER, ROV •  BOTTOM RECOGNITION

Survey Equipment

SSS Klein 5000, Gradiometer 4-axis Marine Magnetics Multibeam Reson 7125 SV2 200/400 kHz

ROV Ocean Modules V8 MVP 200 Broke Ocean MVP Fish USBL

SSS Winch

Technology  of  the  amuni=on  detec=on  

 Three  stages  of  geophysical  surveys  in  the  amuni=on  detec=on  and  recogni=on  required  employment  of:    • Acoustic techniques : Side  Scan  Sonar,  Multibeam  Sonar,  chirp  broadband  echosounder/  multifrequency  split-­‐beam  echosounders/  parametric  sonar  • Magnetometric  techniques  • ROV  –  positioning,  visualisation  and  sampling      

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Hydroacoustic will also deliver data to prepare bathymetric and type of sediment maps (FOR MODELLING OF TRANSPORT OF TOXIC SUBSTANCES).

SIDE SCAN SONAR

¡ The sensor is towed behind the ship near sea bottom. The swath width is typically up to 100 m.

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SSS    and      unmanned  underwater  vehicle  (UUV)  

SSS  SIGNAL  PROCESSING  

Target  detec=on  –  hard  boNom  

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Targets

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SSS  IMAGES  PROCESSING  

RAW  DATA   PREPROCESSING   PROCESSING:          GEOMETRY  &                        

POSITION  CORRECTIONS  MAPPING  

 

POSTPROCESSING:          

INTERPRETATION  BY  OPERATOR  OR  

COMPUTER  ASSISTED  

c  PRODUCT  

c  ADDITIONAL  INFORMATION  

DECISIONS    

•  HIGHER  SHIP  SPEED  (BIGGER  AREA  COVERING)  –  LOWER  RESOLUTION  (ALONG  PATH)  

•  HIGH  VS.  LOWER  FREQUENCY  •  HOW  MANY  PIXELS,  RESAMPLING  ?  REDUCING  GREYS  LEVELS?  (GAINS  -­‐  MEMORY,  TIME  CONSUMING  OPERATIONS)  

•  WHAT  KIND  OF  TRANSFORMING  OPERATIONS  (SMOOTHING,  STRETCHING,  CONTRASTS,  COLOURS,  ETC.)  

 

STRATEGIES  OF  SAMPLING  (WITH  SONARS)  

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PLANNING AREA COVERAGE

•  If full coverage of the seabed is required swaths be should overlapped

by at least 50% to achieve 100% coverage. •  Swaths are typically overlapped by 20 to 30%. •  To achieve the maximum coverage possible, the transducers must be a

suitable height above the seabed (between 10 to 20% of the swath width).

•  For most 100kHz systems 10% per side with swaths widths could be maximized up to 200m per side with the fish traveling 20m from the seabed.    

 Op=mis=cally    •  4  *1850[m/hour]*200  m*1  hour/0.3          1  sq.km/hour  

Product – map of target distribution All classes of targets Subarea T

EQUIPMENT  MulTbeam  Sonars  

 Appropriate for imaging of the wrecks, protruded objects and seafloor mapping in water depths between 0.5 and 150 meters.

 Theoretically swath width 10 x water depth, however for the above 100 m depths and sound refraction the real swath width, target recognition is substantially diminished.

 However - the minimal diameter of the spot at 100 m depth is 2.5. m !

MAIN TASKS –bottom topography + detection and visualisation of bigger objects

Technology  of  the  amuni=on  detec=on  

•  Even  though,  in  the  last  couple  decades,  many  systems  and  algorithms  had  been  introduced.    

•  One  of  the  limitaTons  of  real-­‐Tme  recogniTon  systems  is  the  computaTonal  or  hardwer  complexity  of  exisTng  approaches.    

•  The  general  problem  of  these  systems  is  their  computaTonal  cost  in  data  pre-­‐preparaTon  and  transformaTon  to  other  spaces  such  as  eigenspace,  Fisherspace  ,  wavelet  transform    or  cosine  transform  

 

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Newest  technologies  

•  Synthe=c  aperture  sonar  (SAS)  is  a  form  of  sonar  in  which  sophis=cated  post-­‐processing  of  sonar  data  are  used  in  ways  closely  analogous  to  synthe=c  aperture  radar.    

•  Synthe=c  aperture  sonars  combine  a  number  of  acous=c  pings  to  form  an  image  with  much  higher  resolu=on  than  conven=onal  sonars,  typically  10  =mes  higher.    (4-­‐5  cm)  

Magnetometric and Remote Operated Vehicle (ROV)

Probably Chemical Munition Objects The image part with relationship ID rId5 was not found in the file.

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Acous=c  boNom    recogni=on  one  beam  classical  echosounder    

Klusek, Tęgowski, 1999 Tęgowski, , 2002

Acous=c  boNom    recogni=on    

•  SIDE    SCAN  SONAR  •  BoNom  type  recogni=on    •  (Object-­‐oriented  classifica=on  of    •  sidescan  sonar  data  for  mapping  •   benthic  marine  habitats)  

•  (Univ.  of  Gdansk  •  IO  PAS,  Sopot  •  P.Paukszys)  

•     

Acous=c  boNom    classifica=on  

Mul=beam  sonar    

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Tegowski, etl al. 2011

 Thank  you  for  aNen=on  

 Kiitos