Ship Detection and Characterization with Generalized

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C! hi nese Journa1  of   El ectroni cs   Vo1 . 17,No. 3,Jul y 2008 

Shi p D etecti on and C  ha '   ract .   eri ●   zat . l ●   on W l ● t ● n  1  

G eneral i zed O pti mi zati on of  Pol ari m etri c  C  ont   rast  Enhancem ent术   LI   Ha i ya n , 一 .HE  Yi j un .MENG  Le i   , 。and  WANG  We nguang 。   ( 1 . I n st i t ut e   o f   Oc e anol o gy ,Ch i ne s e   Ac ade my  D ,Sc i e nc e s ,Qi ngda o   266 071 ,Chi na )   ( 2. Gr ad uat e  Uni ve r s i t y   o f  t he  Chi ne s e   Ac ade my   o f  Sc i e nc e s ,Be i j i ng   1   0 00 49 ,Ch i na)   ( 3. Sc ho ol   o f  EI E,Be i han g  Uni v er s i t y ,Be i j i n g  1   000 83 ,Chi na )   A bstract —— A  G enerali zed optim izati on algorithm  of 

i nt roduced f or  anal ys es  of   pol ri a m etri c  datat 5 J B esi des  thes e  .

c  param eter s.t he   pol ari zati on  degr ee  PD  L o J  and  c o-   pol ari metri c contrast  enhancement( GOPCE)i s  proposed  polarimetri to f i nd optim al pol arim etric states and coeff lci ents to m ax.  

pol ar i zati on  pha s e  di f f erence ( 1  ̄ hh 一

im i ze the received Pl ow er rati o of ship to ocean clutter,   w hich faci litates shi p detecti on. T he m ethod is vail dated 

wi th a r eal  SIR_ C/X i m age. The resul ts i ndi cate t hat.   rather than opti m al  polarim etri c contra s t enhancem ent,   G 0 P C E apparently im proves the contra s t of shi p to sea 

by introducing the polarim etric feature vector.   K ey w ords ——

al so  charac teri z e  the   scat—    

t e r i ng   me c hani s ms   of   i l l ume d   obj e c t s 【  . The   c o - pol ar i z a t i on  scatter i ng r at e  of   shi ps  i s   l arger   than  that  of   ocean.H owever,  

the di ference  i s  not   di sti ncti ve.   Pol ar i me tri c   charac ter i zati on  i s  an  efecti ve  m ethod  to  di s-   cri mi nate  di fer ent  s cat teri ng m echani s m s. However,how  t o 

O ptim izati on, Polari m etri c  syntheti c 

i ncorpor ate  these  pol ar i metri c par ameters  and the r ec ei ved  pow er  f or  shi p detecti on i s an unsol ved pr obl em .   I n thi s 

aperture radars,Ship detection.  

study,we  i m proved  the  G eneral i ze d  opti mi zati on  of   pol ari m et —  

r i c   contra st   enhancement( GoPCE)me thod  or f   shi p  det ecti on,  

I.Introducti on 

w hi ch i ncl uded not  onl y t he di ierence of  f recei ved pow er  be—  

Shi p detecti on i s  a key r equi r em ent  i n m i l i tar y, coas t—  

tween shi ps  and  ocean backgr ound,but  al so the  pol ari m et ri c   i nf o rm ati ont s J T he  new   m ethod constr uc ts  a new pol ari m et —   .

guar d,f is her i es,and comm erci al  tr anspor tati on s ec tor s. The  i m por tance  of  tr ans mi tr ecei ve  ant enna pol ar i zati ons  on s hi p  de tectabi l i t y ha s  been  w el l   know n now . Futur e satel l i te  Syn—  

theti c aper ture radar s( SAR)woul d provi de vari ous  pol ar—   i zat i on channel s  and addi ti onal  i nf o rm ati on. w hi ch per mi t s  

bet ter  char acter i zati on of  i l l umi nated objects. For  exampl e.  

ri c f eatur e vector  to charac teri ze  the di ier f ence backscatter —   i ng m echani sm  bet w een shi ps and ocean. T he i m pr ovem ent  of  G o PC E rel ati ve tr adi t i onal  O pti mi zati on of  pol ar i m etri c 

c ont r st a   e nhanc e men t( oPcE)i s   quan t i ie f d  wi t h  ma x  po we r ,   m ean  power,and t he   corr espondi ng contr as t.  

the  Envi r onm ental   satel l i t e  A dvanced  syntheti c   aper ture  radar  

i zed Opti mi zati on M ethod  ( ENVI SAT ASAR)ope r a t e s  i n  t he  al t e r na t i n g  pol ar i z at i on   II.The G eneral m ode. RADARSAT一 2 and ALOS—PALSAR are f ul l y pol ari —   m et ri c SARs.W i th  thes e pol ari m etr i c  program s,i t  i s i m por —  

The tradi ti onal  0 P 

i s  t o choose opti m al  pol ar i zat i on 

t ant   to a s ses s  shi p- s ea  contr st a  i m pr ovem ent  that  can be  ob—  

states  by a pow er  i m age  . For  obtai ni ng bett er   cont rast  en—  

t ai ned by usi ng  the  addi ti onal  pol ari zat i on i nf or m ati on.  

hancem ent,however,i t  i s   not   suf i ci ent   t o  use  the  power   i m age 

Ful l y  pol ar i m etri c data contai ns potent i al  i nf o rm ati on  about   the  char act er i zati on  of   tar get   backs catt eri ng[ 1一引



Such 

i nf o rm ati on i s hel pf ul  f or  param eter  extracti on and cl as si —  

icati f on. These tool s,whi ch i ncl ude  ent ropy[  ̄j ani s otr opy  ,

A[ 2 】 ,a nd t he  pol a r i me t r i c   s c a t t e r  ang l e  a[ 3 】 ’we r e  a ss i g ne d 

onl y.T her ef ore   w e  propose  G O P CE f or   shi p de tecti on,w hi ch  i ncl udes   not   onl y  the  opti m al   pow er,but   al so  the  pol ari m etr i c   i nf or m at i on of  shi p and  ocean.  

1.   Choosi ng pol ari m etri c characteri sti c param e-   ters 

a sol i d physi cal  i nterpr etati on wi th ref er ence to target  scat —  

Som e  chara c teri sti c par am e ters  can r ef lect  di fer ent  scat —  

t er i ng  m echani s m s.C l oude  and  Pot ti er’ s   param et er s  have  be-  

teri ng  mechani sms of  obj ec ts,whi ch  can  be  used f or   shi p de-  

cam e  s tandard t ool s  or f   targe t  char ct a er i zati on  and have  been 

tecti on. H ow ever,the accurac y of   shi p detecti on r el ates  t o 

us ed as  the  ba si s  f or  devel opi ng new cl s si a icati f on m ethods 

the  di ver si t y  of   s hi ps  and  the  compl exi ty  of   oceani c  s tat e.W e 

M anuscri pt  Recei ved M ar.2007;Accepted Nov.2007.Thi s work i s supported by the N ati onal  Natural  Sci ence Foundati on of  China 

( No. 40276050),t he   Pr oj ect   of   Shar i ng  Envi s at — ASAR  Dat a  and  t he   Open  Fund  of   Ke y  Labor at or y  of   Oc ean  Ci r cul ati on  and  Wave,Chi ne se   Aca demy  of   Sci ences( No. KLOCAW 0808) .  

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542 

Chi nese  Journal  o f  El ect roni c s 

2008 

c hoos e s everal  char act er i s ti c param et er s  to cons truct  the po-  

wher e  M  and  N  denot e  t he   sel ecte d  pi xel   number s   of   shi p  and 

l ar i m etr i c  f eatur e  vector  of   G O PCE .  

s ea,r espec ti vel y.The  opti m al   s tat es  gm and  hm ar e  the  sam e  

Too  f ew   char act er i s ti c   param eters   can  not  c haracteri ze  t he 

s  that a  of  t he  tra d i ti onal  O PC E probl em   w hi ch can be ob-  

s c a t t e r i ng   me c hani s ms   o f   o bj e c t s   r oundl y .On  t he   ot he r   hand,  

G  tai ned by Yang【  …. The  vi r tue  of   thi s  i t er ati on al gori thm  i s  

too m any par am e ters  wi l l  l ead to hi gh com putati onal  l oad,  

that  i t  i s  not  rel ated to the i ni ti al   val ue. The  opti m al  co ef -   : 

P 

whi ch ar e of f se t by ti m e cos t. T0  charac teri ze the di ierent f  

ici f ent  X  can be obtai ned by s ol vi ng the  ei genval ue  probl em  

scat teri ng  mechani sms   bet ween  sea  cl ut ter   and  s hi p  objec ts  i n 

propos ed by  Yangt s 1.  

a r obus t  m anner,the  use  of   3 to 5 par am eters   turned out  t o 

∑  r 

gi ve bet ter  r esul ts.B oth  entr opy and a n i s otr opy  ar e  deduced 

( 5)  

f r om t he ei genvM ues  of  coherence matr i x. They are  r el evant  each  ot her  and ani sotr opy i s  the  suppl em ent  to  entr opyDJ ,

×  h 

so 

we  us e  entr opy  rather  t han  ani sotr opy. The  vari abl e丘 i s   cho—  

sen  owi ng  to i ts  r ot ati on i nvari ance  on pol ari zat i on  basi s  and  repres enti ng  t he   i nf or m ati on  of   ei genvectors.However,the   di f -   f erence  bet ween sea and shi p co— pol ari zat i on scatt er i ng r ati o 

g   wher e[ n( s hi p) 】= [ r i ( s hi p) r j( shi p) ] 4 ×4  and [ n( s e a) 】 =  [ r i ( s e a) r j( 8 ea) 1 4 x4.I t  i s  e a s y  t o  pr o ve  t ha t  t he   ei ge n ve c t or  

s soci a ate d w i th  the  m axi m um   ei genval ue i s  the  opti m al   coef -  

i s  not as obvi ous  as  that of   co— pol ar i zati on phas e di ierence. f  

ic f i en t   ve c t or  

Ther ef ore  the co— pol ar i zati on pha s e di ier f ence i s  i ncl uded i n 

r ea s on  w hy  we  adopt  the  second order  f uncti on of   the  pol ar i —  

t he pol ri a m et ri c  f eatur e vect or. P D  i s  rotati on— i nvari ant  pa—  

m etri c  e at f ure  vector.  

=( Xl, x2 , x3 , x4)  of   t he   Eq. ( 4 ) .Tha t   i s   t h e  

r ameter  whi ch can be  used f or  shi p detecti on. Thus  t he po—  

l axi me tri c   eatur f e  vector  i ncl udes   H 西hh~ " "P ,whi ch  can  be 

III.Case A nal ysi s 

wri tten a s 

r=[ H 

 ̄hh 一”   P ]  

( ¨ 

1 .

D ata descri pti 。n 

T he  pol ari m etr i c   f eatur e  vector  i ndi cates   the   di fer ent   scat—  

ter  m achi nes  bet ween shi ps  and ocean cl utter.W her e a and 

西h^—Ⅳ 口 a e  nor m al i zed  wi t h t he  f ol l owi ng  f uncti on 

no' r= ( ma x—para) /( ma x—mi n)  

’ I   he   da t a   us e d  i n   t hi s   c as e   a nal ys i s   Wa s  ac qui r e d  y  b Shu t t l e  

i ma gi n g  r d ar a — c/ x— band  Synt he t i c   ape r t ur e   r a dar( SI R- C/ X—   SAR)o n Oc t .4,19 94   of   Hon g  Kong  Vi c t or i a  Por t( a bout  

4. 05。,N22. 106。) . The  i mage mode i s  a mul ti — l ook cor n-   ( 2 )   El1 pl ex  and  the  num ber  of  l ooks   i s   5. 2. The  sens or   oper at ed  i n  C 

wher e  para  repr esents   and 西hh』",r es pecti vel y.  

band and  the  r es ol uti on  i s   12. 5m .T he  span  i m age  of   t he  dat a 

2.The G OP CE m ethod f or shi p detecti on 

∑ 帅   R 

In GoPCE.we  ne ed t o  ind an opti f mal  f u ncti on  cont ai n—   i ng t he  rec ei ved power. H o w ever,i t  i s  i m pos si bl e  to f ind  out   、 竺,   the  exact  f o rm  of  the opti m al  f unc ti on. So i t  i s neces sar y  to 

m ake   an  s sum pt a i on  on  the  opt i m al   f uncti on  or f m .Si mpl y,we  s sum e a   t hat   t he  f unct i on  or f = m    consi sts   of   t w o  f act ors.O ne   f ac —   ,< 

tor  i s   as soci ated wi t h  the  t ar get   scatteri ng  char act er i s ti c s  and 

一 Ⅳ  t he ot her  i s  the recei ved po w er. For  conveni ence,the  tar get   sc att eri ng  charact eri s ti cs  ar e r epresented  by the  second order  

∑一  

f unct i on of   pol ari m etr i c  ea f R  ture vector.Addi ti onal l y the r e—   、 竺  ,   e cei ved  power  i s  cal cul ated  wi t h  the  Kennaugh mat ri x  and t he  0  St oke vector. Then t he pr obl em can be  model ed as  t he  e x—   t rem um   probl em  of   the  f unct i on  de fned a s 

i s   s hown   i n  Fi g. 1( 0) ,i n   whi c h  t he r e   ar e   many   s i g nal s   di fe r e n t   rom  the f  sea. For  si m pl i icati f on.we cal l  thes e si gnal s  a s  sus.   pi ci ous  si gnal s  m arke d w i th  di ierent f  num ber s  1-9. They are 

jus ti ied a f s shi ps  wi t h l ar ge  pos si bi l i ty usi ng t he  tradi ti onal   s i ngl e  pol ari m etr i c  SAR  data.Judge d  by s i ght,the   str ong  si g—   nal s  l一7  are  s hi ps.  

The  typi cal l y  s trong s hi p  s i gnal s   3 and t he  t ypi cal   sea  si g-  

nal s   marked  wi th  t wo  r ect angl es   i n  Fi g. 1f a1   ar e  s el ected  to  cal -   cul ate   the  average  K ennaugh m at ri ces   of   shi p and  ocean.T he  

r eturn waves  of  s hi ps  and sea ar e di fer ent  i n both i ntens i t y  and scat teri ng characteri sti cs,e. 口. ,the random ness,the  di f -   er f enc e i n  tr i hedra1   di hedral   scatteri ng  and  surf ace  scatteri ng,   the  degr ee   of   pol ari zati on  and  the  co— pol ari zati on  pha se   di f f er- _   ence.They  re a  r el ated  t o  H,   ,P  ,and  hh』口,res pecti vel y.  

i= l , 2, 3, 4  

( 3)  

Thes e  param eters   can  be  obtai ned  wi th  the  sel ecte d  data.T he   opti m al  pol ari zati on s tates  gm ,^m are  gai ned by sol vi ng  the  

e c ond  pa r t  o f   Eq. ( 4)wi t h   t he  i t e r a t i ve   al gor i t hm  where rl, r2, r3  and r4  ar e H ,   , ̄hh一" " and PD,r espec—   s

wi t h  

t i vel y;   l,  2, x3  and  4  ar e t he coem ci ent s  whi c h can be ob—  

t he ei genval ue  method.we  can  obt ai n opti m al  coemci ent   vec—  

tai ne d  by  sol vi ng  an  opti m al   pr obl em ;t   denotes   t he   tr ans pose;  

to r   m.I ns e r t i ng  t he s e   par ame t e r s   i n   Eq. ( 3 ) ,we   ca n  o bt a i n 

h= ( 1 , hl , h2, h3 )  and  g= ( 1, gl , g2, 93 )  ar e   t he  S t o ke   v e c —  

t he opti mi zed  power.   2. Com pari son G 0 PC E w i th 0 P CE 

tors.s ubscri pt  m  r epresents  t he  opti m al  pol ar i zati on s tates;  

K  i s   the  averaged  Kennaugh matr i x.   The ai m  of  m athem ati cal  m odel  of  G O P CE i s  to f ind 

X=( Xl , x2, x3,  4 )   ,g  and  h  ro f m  t he   f ol l o wi ng   f unc t i on:  

Fi g. 1 ( b )a nd Fi g. 1 ( c )s ho w t he  s pan i ma ge s  a ss oc i a t e d  wi t h   OPCE  an d  GOPCE.Compa r i ng   Fi g. 1 ( 6 ) ,Fi g. 1 ( c )wi t h  Fi g. 1( 0) ,t he   c on t r as t   of   s us pi c i ous   s i gna l   8   i s   i nc r e se a d   whi l e   that  of  suspi ci ous  s i gnal  9 i s  decrea s ed,and the vari ati onal  

m a X lm lze 

l / ME   [ ∑4 _   i ( s h i p ) ] 。   1 / Ⅳ∑ …[ ∑ 4   x i r i ( s e 。 ) ] 。   、 , h t  ( 斌  s ^  ) 】 9  

de gr e e   i n  Fi g. 1 ( c )i s   l ar g e r   t han   t ha t   i n   Fi g. 1( 6 ) .I n  f ac _ t ,t he   suspi ci ous  si gnal s  1—7  experi enced  the  sam e c hanges  as  si gnal  

8 duri ng the proces s.   However,the power  of  the sus pi ci ouS  

subject   to 

g}+I q ;+  =1 , h +h;+h;=1 ,   + ;+ ;+。 :1( 4)  

si gnal s  1—7  i s   too  str ong  to s how  the  var i ati ons  as  that  of   si   nal  8 i n  the  gral y i ma ges.  T he  corr espondi ng quaⅡt i 矗cat i onal  

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Shi p  Detecti 。n  and Char acteri zat i on wi th General i zed Opti mi zati on  of   Pol ari m etri c  Contr ast  Enhancem ent  

543 

perf orm ance  es ti m at i on i s  show n i n Fi g. 2,w hi c h i ncl udes   the 

l ncreased i s not  the  sam e. The di ferences  i n physi cal  pr op-  

var i at i on  of   t he  pow er   and the  contrast   enhancem ent.  

erti es  of  shi ps  such a s  m ateri al ,st ructur es, and shapes  m ay  account  f or   i t.It   i s   appar ent  t hat   the  sus pi ci ous   si gnal   9 i s  an  except i on,w hi ch  has   the   sam e  change   tendency  as  ocean  at   the  thr ee  pha s es. Ba s ed on  the  si mi l ar   vari ati on t rend,suspi ci ous  

10 

si gnal   9 i s   j usti ied  f s  ocean  a cl utt er.  

20  30  40 

40 … … … 一 …

50 

( n)  

60  70 

3 0  20  40 

一 ……  

{ I l 礴 l l l l   BP o Oc  E :  

800  r…



… …

~ ——一 … 一 1

j  



n 

  ; 口 GOP C E   60 0; _ B O 

; f  

60  80  1 00  120  140  160  180  200  OPCE 

L 

10  20  30  40 

L一 {  

50 

40 

60 

( c)  

70 

20  4 0   60  80  100  120  140  160  180  200 

器 3O 

GOPCE 

:   8 20 

1 0  20 

≥ 

&1 0  

30  0   4 50  矗 ≥ 0Q 囊  

60  70  —







I 《 l     8   l   l   l : I  

塞 o   s ea  1  2 3  4 5  6  7 8  9 



 

s ea  1  2 3  4 5 6 7  8  9 

Sea  20  4 0 



l  n  









60  80  100  120  140  160  180  2oo 

+  

Azi mut h  pi xel s  

Fi g.2.( 0) ,( 6 ),( e)and ( d).The  c ol umn di agr ams  of  max  power,m ean power,the contrast of m ax power and 

Fi g.1.The span i m ages of BO ,OPCE and G O PCE,respec—  

m ean power cal cul ated wi th the average Kennaugh 

tivel y. The num bers 1—9 m ark suspi cious  si gnal s. X 

m atri x of  shi p 3 duri ng three pha s es:BO,0 PCE and 

axi s and y axis represent the num bers of  pi xel s i n az—  

G oPCE.In every group.the f irst.the second and the 

i m uth and range directi on,respecti vel y 

thi rd rectangle represent  the  results  of  BO,OPCE and  Go PCE.respecti vel y 

The  par am et ers  of   m ax— b— o.m ax_ i n— o  and m ax— a— o  repre—  

sent   the   m axi m um   power   of  BO.oPCE,and  GO PCE,r espec—  

Above anal ys es show that  the  GOPCE i s  mor e efecti ve  

th a n t radi ti onal  OPCE i n i m provi ng  the contr st a  of   the  SUS .   t i vel y. In a si mi l ar  way.m ean— b— o. m ean_ m— o an ( _ — — 【 d  p 一   me - I an—   0u. a— I o^     f , 0口) (   至  pi ci ous  si gnal s  1—8.   M or eover. the decr eased degree  of  the  can be  ref err ed to as  t he m ean power  at  three  phases. C on-   uspi ci ous   si gnal   9 wi th GOPCE i s  l ar ger   than  that   of  OPCE.   tr ast  denotes  t he  power  rati o  of  shi p to s ea  i n  dB.T he  m ax—   s s uspi ci ous   si gnal   9  i s   reverse  t o  other  suspi ci ous   i m al  power   onl y shows  t he i nf or m at i on of  one l ocal   pi xe1 .At   H owever.w hy  the  s am e ti m e,i t  i s  di rectl y r el at ed to the  contr ast  and can 

s i gnal s ? Thi s  questi on can be  e xpl ai ned by t he pol ari m et ri c  

provi de a m easur em ent  of s hi p— sea r ati o。 T he m ean power  

f eature vector,whi ch wi l l   be anal yze d bel ow .  

changes  w i th  the  num ber s of   the  pi xel s,but  i t  r epr esent s  the 

3. Characteri sti c vector anal ysi s  

gener al  i nf or mati on  of   the  objects.Bot h parameter s  des cri be  

The   charact er i s ti c   paramet ers   H, a,PD ,  ̄hh一 "  ar e  showed 

i n Fi g. 2. T he  m a x i m um   pow er,m ean power,the  cont rast  of  

i n  Fi g. 3( a) ,( 6 ) ,( c ) ,a nd( d) ,r e s pe ct i v e l y .The y   de s c r i be   di fe r —   e nt   s c at t e r i ng   me c hani s ms   be t wee n   s hi p  a nd  oc e a n.Fi g. 3( a) ,   ( 6 ) ,( d) ,an d( c)i ndi c a t e   t ha t   hi gh   H, l a r g e  a ngl e   a nd ̄hh   ,  

m axi m um  power   and m ean  power  of   BO,OPCE  and G OPCE 

l OW P  D  appear   i n  som e ocean areas  except  shi p s i gnal s.O b-  

are  al l  show n i n the  f igures. I n every group,the f ir st, the  

vi ousl y,f al s e  de ci si on  wi l l  be  m ade  i n  shi p  det ecti on wi t h  any 

the  pow e r  f rom  di fer ent  poi nt s  of  vi ew .   The advant age s of   opti m al  m ethods  can be  show n cl earl y 

second,and t he thi r d rectangl e  represent  the  r esul t s  of  BO,  

one of  the f o ur  pol ari m et ri c  param et ers. A s  the  def ini t i on of 

o PCE.and GoPCE.res pecti vel y.   It  i s obvi ous  that  bot h 

pol ar i m et ri c   f eatur e vector   show i ng,i t   com bi nes  t he  i nf o rm a-  

opt i m al  m et hods  decrease  the  power   of   retur n wave  f rom   the 

ti on of   the  o ur f  pol ari zati on param et ers  and can em body  the  

ocean  w hi l e   they  rai se   that   of   the   sus pi ci ous   si gnal s   1-8,w hi ch 

di 行e rence of  s catt eri ng m echani sm s bet ween shi p and ocean 

r esul t   i n  t he  i m pr ovem ent   of  t hei r   cont rast.C om par i ng  the   re.  

r oun dl y.Us i ng   t he   ir f s t   f ac t o r   i n   Eq. ( 3 )a nd  l oa di ng   t he   o pt i —  

sul ts   of  GOPCE  wi th  those  of  oPCE.the   f or m er   r educes   m ore  

m al   coem ci ent s.the  pow er   enhancem ent   wi th  the   pol ar i m etri c 

pow er  of   oceani c  r eturn wave, at  the sam e t i m e i t  i ncrea s es  

f e at ur e   v e ct or[ ∑ xi ri ] 。ca n  be   g ai n e d  a nd  s ho wn  i n   Fi g. 3( e ) .  

more   power   of   s uspi ci ous   si gnal s  1—8.W i th t he  doubl e   efects.  

Co mpar i ng   Fi g. 3( e )wi t h  Fi g. 3( a) ,( 6 ) ,( c ) ,( d) ,t he   hi gh  va l —  

GOPCE ha s  bett er   per f or m ance   of   contrast   i m provem ent   than 

ue s   of[ ∑ xi r i ] 。( >2)al mos t   appe ar   i n  t he   a r e s  a o f   s u s pi c i o us  

OPCE.The  resul t   i s  expected  because  m ore  i nf or m at i on  i s   i n—  

s hi p si gnal s. T her ef ore, t he pol ari m etr i c  f eat ure vect or can 

cl uded i n GOPCE than i n OPCE wi th pol ari met ri c vector。  

i m prove  the  accuracy of  shi p detecti on  rel ati ve  t o  any one  of  

H owever, t he degree to w hi c h the suspi ci ous  si gnal s  1-8 ar e 

t he  f our  pol ar m etri c  param et ers.  

维普资讯 http://www.cqvip.com

Chi nese  Journal  o f  El ect roni cs  日 

2008 

ture vector. I n gener al ,t he  det ect i on per f or m ance  i m pr oves 

3O 

O. 8 

s  mor a e benef ici al   i nf o rm ati on  i s  i ntr oduced i nto t he  deci si on 

0. 6 

vari abl es.  

0. 4 

5O  O. 2 

IV .Concl usi ons 

70  2O 

60 

lo0 

140 

l8O 

Wl e have esti m ated the i mproved perf orm ance of  OPCE 

n 

and GOPCE i n shi p det ect i on. Both m et hods can enhance 

lO 

70 

t he  cont ra st  of   s hi p t o s ea.whi l e  the  i m provem ent   of   t he  l at —  

3O 

5O 

t er  i s  l ar ger  than t hat  of   the f ormer. The  rea s on i s t hat  we 

5O 

3O 

adopt  GOPCE met hod,whi ch not  onl y em pl oys  t he  recei ved  power   rati o  of  shi p  t o  ocean  cl utt er  or f  contr st a  enhancement,  

70 

1O 

2O 

60 

lo0 

l40 

but  al s o ut i l i zes  t he di fer enc es  of  s catt eri ng mechani s ms  be-  

l8O 

t ween shi p and ocean wi t h pol ari metri c f eatur e vect or. The 

PD  lO 

pol ari met ri c f eat ure vect or  i ncor porates  t he i nf orm ati on of 

O. 8 

the  f our   chara ct eri s ti c  parameters   H,a,Chh一 ””,PD,whi c h  i m-  

0. 6 

3O 

proves   t he  c curacy  a of   shi p  det ect i on.The  pol ar i m et ri c  f eatur e 

0. 4 

5O 

■ 

vector,di re ct l y  rel ated  to  the  s catt eri ng  me c hani sm ,account s 

O. 2 

70  2O 

■—  lo0 

6O 

140 

■ U■ l8O 

or   the  cont ra st   i mpr ovem ent ■  f ■罔= 5 2   2   5 l = =    ■  < O ,    because it enlarges the power of 

妒 

shi ps  whi l e s uppr ess es  t hat  of   ocean. Furt herm ore,choosi ng  di f f erent l  shi p Kennaugh m atri ces  does  not  efect  shi p detec-  

lO  l40 

ti on. Theref or e,the good qual i ti es of  GOPCE can be us ed 

3O 

l00 

t o  det ect  shi ps   under  hi gh oceani c  st ate  and l ow  rat i o  of  shi p 

50 

60  20 

70 

6O 

lo0 

1 40 

l8O 

to s ea.However,the GOPCE  m ethod,whi ch  depends  on t he  s hi p and s ea  ar ea s  sel ecti on,i s  sensi ti ve  to  the physi cal  pr op-   ert y,str ucture  and conf igurati on of  shi ps. To overcom e i t,   t he   si gnal s   of   shi p  sel ect ed  to  cal cul at e  the  opti m al  s tates   and 

[ Zzi ri ] 。  

opt i m al  coef i ci ent  vector  shoul d embody the  t ypi cal  s hi p i n—  

lO 

f orm ati on  i n  SAR  i mages.Fur ther   i nvesti gati ons   r e  a curr entl y  3O 

bei ng conducted  to conf irm t hes e r es ul t s wi t h ot her  dataset s  

50 

and  gr ound— trut h  data。These  encour agi ng  resul ts   or f   s hi p( 1 e-   t ect i on and c hara c teri zati on coul d moti vate t he us e of  f ul l y 

70 

20 

60 

lo0 

l40 

l8O 

pol ari m etri c  satel l i t e SAR   data.  

R ef erences  

Fi g.3.The i m ages of characteri sti c pa r am eters 日 ,a,P D ,  

 ̄ h h   a n d   p o l a r i me t r i c   f e a t u r e   v e c t o r[ ∑ ̄ i T i ] 。 .X  axi s and Y axi s  represent the num bers  of  pi xel s in az—   imuth and range di recti on,respecti vel y 

I n  Fi g。 3,t he s us pi ci ous  si gnal s  1-8  have t he  character s  of  

hi gh H ,l ar ge  a and Chh一   ,l OW PD. I t  i s  wel l  known that   t hese ar e typi cal  f eatur es  of  s hi ps.so suspi ci ous  si gnal s  1—8  can  be  di st i ngui shed  f rom  the  backgr ound  of  ocean.However,   suspi ci ous  si gnal  9 has the  chara c teri zati on of  l ow H .s m al l  

a and Chh_  ̄  ,hi gh PD,whi c h ar e the t ypi cal  charact ers  of   ocean.Ba s ed on thes e f eatur es,sus pi ci ous  si gnal   9 i s  f ur ther  

j us t i ie f d   s  a oce a n  cl ut t e r . Ho we v e r ,t he   po we r   o f   s us pi c i o us   si gnal  9 i s  mor e than f ive ti mes  of  ocean. Sus pi ci ous si gnal  

9 wi l l  be deci ded a s  a shi p gener al l y wi th CFAR ,i n whi ch 

f 1 1  S. R.Cl oude,E.Pot ti er ,“A  r evi e w  of   ta rget   decomposi t i on  th e-   orem s i n rada r  pol ari m etry .IEEE Transactions on Geoscience  and Rem ote Sensi ng,Vo1 . 34,No. 2,PP. 498—518,1996。  

[ 2】s. R.Cl oude,E.Pott i er,“Appl i cati on  of   t he   H/A/al pha  pol ar i —   m etri c decom posi ti on theorem for land cl assi ication”,Proceed- f  

i ng  o l  SPI E.1997  f 31  S  R.Cl oude, E.Pot t i er ,W . M  Boerner, “ Uns uper vi s ed i m—  

age cl ss a i icat f i on usi ng  t he ent r opy/al pha/ani sot r opy method  i n radar pol r im etry”, /n Proc. a  

L AIR SA R Sym posium ,  

Pa s adena,Cali f orni a,2002.  

『 4】s  R Cl oude,E Pott i er,“Concept  of  pol ar i zati on entr opy i n  optical   scattering”,Opt ical  Engineering,V_ 01. 34,No. 6,PP.1599-  1610,1995 

f 51  L Ferr o- Fami l ,E Pot ti er ,J. S.Lee,“Uns uper vi sed cl as si ica f -   tion of mul ti 一  ̄equency and f ul l y pol ari m etric SAR i m ages 

the  thres hol d i s not  a s  l arge  a s  f ive  ti mes  of   ocean  The  ad_  

ba sed on H/A/Al pha- Wi sha rt  cl ss a i ier f ”.饱 EE 

vant ages of  pol ari m et ri c  f eature vector  are  shown cl earl y i n 

on G eoscience and Rem ote Sensi ng,Vb1. 39,No. 11,PP. 2332- 

Fi g . 3 ( e ) .Th e   m ̄ x i mu m  2 . 7 4   o f[ ∑x i  ̄ i ] 。h a p p e n s   i n   s u s p i —   ci ous   s i gnal   6.Ot he r   s us pi c i o us   s hi p   s i gn al s   v al ue   o f[ ∑ Xi r i ]   e x c ept   s i g nal   9   i s   l a r ge r   t han  2.Whe r e s  a t he   v al ue   of[ ∑  】   f or   m ost   ocean  cl utte r  i s  l ess   than  1.and  the   m axi mum   of   sus-   pi ci ous si gnal  9 i s  0. 52. Thi s expl ai ns  why t he contr st a  of  

nsact i ons  

2342,2001.  

f 6】M.Bor n,E.Wol f ,Pr i nc l es  o l  Opt i cs:El e ct r omagnet i c The・   ory   olPr o pagat i on,Int er fe re nce   and  Di fract i on  oyLi g ht ,Per g-   am on Press,Elm sford,N . Y .1959.  

f 71  R.T0uzi ,“ Cal i br at ed pol ar i met r i c SAR dat a f or  shi p s et ec -  

t i on”./ n IGARSS’ O0  Pr oc ee di ngs  o l t he I EEE I nt er n at i onal  

suspi ci ous   si gnal s  1—8 i s  i ncreased  whi l e  that  of   si gnal   9  i s   de—  

Geoscience  and  R em ote Sensi ng  Symposium,Honolulu,Hawaii,  

crea s ed.W het her  t he   enhancem ent   or   decr ease   wi t h  GOPCE,  

24—28.Jul y 2000.  

i t  i s  appar ent  that  they benef it  to usi ng t he  pol ar i metri c  f ea-  

[ 8】J.Yang et  a1 . ,“Gener al i zed  opti mi zat i on of   pol ar i me tr i c  con-  

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Shi p  Detecti on  and Characteri zati on  wi th General i zed  Opti mi zati on  of   Pol ari metri c Contra st   Enhancement  

545 

trast enhancem ent .IEEE ‰ nsact ion on Geoscience and Re—  

of interest are: Study of ocean wave and wind retrieval  al g 

m ote Sensing Letter,V. 01. 1,No. 3,PP. 171-174,2004.  

rithms from m i crowave sensors;Ocean rem ote sensi ng by X band 

f 9】A. A.Swart z,H. A.Yueh,J. A.Kong,“Opt i mal   pol ari zati ons   f or  

radar;El ectrom agneti c wave scatteri ng by random rough surfaces;  

achi e vi ng  maxi mum  c ont ra st   i n  r adar   i ma ges ”.Jou)  ̄ nal   o f  Geo—  

Ocean wave and current data a s si m il ati on wi th satel l ite data;Som e 

physical  Research,V_ 01. 93 No.B12,PP. 15252—15260,1988.  

m arine appli cation research using satel li te data.  

f 101  J.Yang et  a1 . ,“Numeri cal  me thods  f or  s ol vi ng t he  opti mal  

M E N G  Lei  was born i n Shandong,  

probl em of  contra s t enhancem ent .IEEE Transactions on Geo—  

China in 1980. He recei ved the B . E.de- 

science and Rem ote Sensinq,Vl 01 . 38,No. 2,PP. 965—971,2000.  

曼 ~ I  LI  H aiyan 

was  born in  Hebei.  

Chi na. She recei ved the B . S.degree f r om  

Hebei  Normal  Uni ver si t y  i n Shi j i azhuang,   Chi na,in 1999  and M . S.degree f r om   O cean 

Uni ver si t y  of   Chi na  i n Qi ngdao,Chi na,i n  2004 and the Ph. D.degree f r om  G raduate  Uni versi ty of  C hinese  A cadem y  of  Sci ences,  

Qi ngdao,Chi na,i n 2002  and  the  M. S.de -   gr e e f r om  Graduate Uni versi ty of Chi nese 

Academy of  Sci ence s,Bei ji ng,Chi na,i n  2005. Hi s research i nterests are ocean re- 

mot e  s ens i ng us i ng mi cr owave  s ensor s( r a-   di omet er s,SAR and al t i met er )and  oc ean  w ave and current data a s si m il ation wi th 

Bei j i ng,Chi na,i n  2007.Now,s he  i s   a  l ec—   turer  in Chi nese Academy  of  Sci ences,Bei 一  

gree f r om  Ocean U ni ver si ty of Chi na in 

。 

j i ng.Her  r es ear ch i nt er e st s  ar e  t he  t he or y 

W A NG

、Ⅳenguang 

wa s  born i n 

Shandong,China i n 1975.He recei ved the 

crowave  ocean rem ote sensi ng.  

H E  Yi jun R el evant   experi ence 

B. S.degree from  Jianghan Petrol eam  In—  

and expertise:El ectrom agneti c f iel d and 

sti tute i n Jingzhou,China,in 1997 and the 

mi c rowave  t echnol ogy- PhD ( 1993),Pos t —  

Ph. D .degree  rom Beihang University,Bei f — 

doctor at Ocean Uni versi ty of China b  tween 1993 and 1995.I have been bei ng a 

ji ng,Chi na,i n  2007.He  ha s  be n  i nvol ved  i n  se veral  pr oj e ct s  of   SAR r emot e  s ens i ng 

research sci enti st at Insti tute of OceanoI - 

and el ectronic warf are. From  June 2007,  

ogy ,CAS,since 1996,and worki ng  on the 

he is  engaged i n the postdoctoral  research 

i n School  of EIE.Bei ha n g U ni versi tv. H i s 

ocean dynam m  pa r am eters rem ote sensi n g 

usi ng mi c ro wave  s ens or s( al t i met er,sc at -  

research interests i ncl ude m any areas rel ated to ra d a r  such as  radar 

t er omet er,SAR a n d ra di omet er s) .Ateas  

polarimetry,target detecti on and el ectroni c warfare.  

I 一 卫 

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