Nghien ciiu - Trao doi
/Sir dung ung dung anh ve tinh Vnredsat-l thanii lap ban do ldp phu rirng ngap man
ty le 1:10.000 khu vUe Vuun Qude gia Mui Ca Mau bang phuang phap dinh
hUdng doi tuang
O N G U Y I N THj OANH TfUdrig Bai hgc Ldm nghiep PHAM VI§T HOA, L^ QUANG TOAN Vien Cdng nghd vu tru - Vien Han lam KH&CN Viet Nam
Tom tat
Bai bio trinh bay Qng dyng anh v§ tinh VNREDSat-1 thanh • lap ban do ldp phQ ri^g ngap man (RNM) phuc vu cdng tie quan ly tai nguyen RNM di giai quyet nhQng van de khd khan hidn dang gap phai d cac dja phuong cd RNM. Phuong phap phan loai sQdung la phuong phap phan loai djnh hudng ddi tuong, la phuong phap phan loai diia vao thuat t d n dinh hudng ddi tupng dupe phit trien va Qng dung trong phan loai nhiJfng nam gin day NgUpc vdi phuong phap phan loai truyen thd'ng, phan loai djnh hudng ddi tupng khdng dua tren d c pixel ddn le ma dua vao toan bd ddi lupng chuyen de ma mat ta ed the nhan biet dUdc trong anh.
Ngoai gia trj phd eiia eac pixel, hinh dang cOa ddi tupng (shape), kien true cCia ddi tUpng (texture) va mdi quan he giQa cac dd'i tupng cung dupc xem xet phan tieh trong phan loai. Nhin chung, qua trinh phan loai djnh hudng ddi tudng CO the chia thanh 2 budc
Vudn Qude gia Mui Ca Mau
ehfnh: Phan manh anh (segment) va phan loai sau khi da phan manh.
Tien hanh thiic nghiem bang tren pham mem eCognition Developer 8.9 vdi anh VNREDSat-1 cd dd phan giai 2,5 m (ddi vdi kenh toan sac) va 10 m (ddi vdi kenh da phd) khu viic Vudn Qude gia Mui Ca Mau, sau dd danh gia dp ehfnh xac va bien tap ban do tren phin mem ArcGIS 10.11.
Dat van de
RCmg ngap mSn la kilu rimg ph4t trien tren vflng dat lay, ngap nl/dc man vimg c&a song, ven biln, doc theo cac song ngoi.
kenii rach co mtdc lo do thOy trieu len xudng hing ngay. RNM phat trien manh 6 vflng nhiet ddi c6 khi hau ndng am va mot ft 6 vung can nhiet ddi. Viet Nam la dat nddc cd nhiiu dilu kien cho RNM sinh 12 Tai nguyen yg M6I truong | Kt 2 • Ttiing 1I1/Z015
trudng va phat triln, nhat la vung ven biln dong bang Nam Bd.
Trudc chien tranh. RNM chiem dien tich tUdng ddi Idn hon 400.000 ha chu yeu la d Nam Bd (250.000 ha). Hai vung d rOng ngap man tap tmng la ban dao Ca Mau (150.000) ha va viing RQng Sac Bien Hda va TR Hd Chi Minh (40.000 ha). Do khai thac rQng 6e lay than, go, cQi qua mQc nen dien tich rtmg giam nhanh. Den eudi nam 1960, riing ehi cdn lai 3/4. TQ nam 1962-1971, chien tranh hda hpc ciia MT da hQy diet 104.123 ha ma 52% d Mui Ca Mau va 41% b RQng Sac, cdn lai la d c tinh d mien Tay Nam Bp.
Oen nay, phan Idn vung bj rai chat dpc hda hpe, riing da tai sinh, nhong thanh phan chii yeu la mam va cha la.
Trong pham vi bai bao nay, tac gia tap trung vao nghien cQu kha nang Qng dung anh ve tinh VNREDSat-1 trong cdng tac thanh lap ban dd Idp phQ rQng ngap man bang phuong phip phan loai djnh hudng ddi tupng.
Thuan toan phan loai truyen thdng thudng dua vao ddc trung phan xa pho cQa anh vien tham da phd vdi dp chinh xic phan loai thdng thudng chi dat khoang 70 - 80 % va khdng dn djnh. Vdi phuong phap phan loai dua vao thuat toan djnh hudng ddi tupng
dupc phat triln va Qng dung nhieu trong phan loai nhCfrig nam gan dp chfnh xac ket qua phan loai tdt hon so vdi d c phQOng phap phan loai thdng thudng khac.
DQ lieu v l phuong phap nghiin cQu
Khu vut nghien edu Vudn qud'c gia Mui Ca Mau la thupc xa Dit Mui, huyen Ngpc Hiln, tinh Ca Mau. Dupc thanh lap theo quyet dinh sd 142/2003/
QD-TTg tren co sd nang d p khu bao tdn thien nhien Dat Mui. Vudn qudc gia nay cd vj tri tai mui dat cUc Nam cQa lanh thd Viet Nam, tpa dp tu 8032' den 8049' vT bac va tu IO404O' den IO4O55' kinh ddng.
Tdng dien tfch tQ nhien:
41.862 ha, trong do: Dien tieh phan tren dat lien: 15.262 ha.
Dien tieh phan ven biln: 26.600 ha. Dien tich dat lien cQa Vudn qudc gia Mui Ca Mau khdng ngiing duoc md rdng mdt each tu nhien, hang nam Miii Ca Mau lln ra biln hang vai chye met bang ngudn phu sa do he thd'ng sdng, kenh, rach bdi dap dQdi su giup sQc cQa bd re phu sinh ciia rtmg mam, dUdc ven biln. Vdi nhiJfng dac tfnh quf gia ve su DDSH va dieu kien lap dia hiem cd nen Vudn qudc gia Mui Ca Mau xQng dang dugc d n g nhan la khu du trQ sinh quyln the gidi.
DQ Udu su'dung Anh ve tinh VNREDSat-1 cd dp phan giai 2,5 m (ddi vdi kenh toan sac) va 10 m (ddi vdi kenh da phd), dp rpng dai quit la 17,5 km, chyp ngay 9/10/2014. Bd dQ lieu dieu tra thue dja tai Vudn Qud'c gia Mui Ca Mau thang 10/2014. Ban do hien trang Idp phu khu vuc Mui Ca Mau thdi dilm nam 2013.
Phuang phdp nghien cifu Qua trinh xil ly du lieu va chiet tach thdng tin b l mat Idp phQ RNM sQ dung phUdng phap phan loai dinh hudng ddi tupng, sau dd danh gia dp chfnh xac ket qua anh sau phan loai dua tren cac sd lieu thUe dja va ban dd hien trang Idp phii nam 2013.
Phan loai hudng ddi tUpng dupc xay dung tren khai niem cho rang tap hpp cae pixel cQa anh se hinh thanh nhieu ddi tupng chuyen d l ma mat ta cd the nhan biet.
Bude xil ly CO ban trong phan tfch ddi tupng anh la cae phan manh anh (segment) chQ khdng phai pixel. Di mat ngudi nhan biet dupc ddi tupng da dupc phan manh (segmentation) thi hang loat thdng tin da dupe xQ ly. Cac thdng tin niy dung d l md ta mdt sd dac dilm hinh dang (shape) kien true anh (texture), cac quan he khdng gian (topology) ciia dd'i tupng dupe phan loai va each tich Bang ma trdn danh gia do ehinh xac phdn loai anh
>70 % 51-70 % 31-60%
<30 % Mat nddc DancU
>70 % 17 0 0 0 0 0
61-70
%
0 13 1 0 1 0
31-50
%
0 1 15 0 0 0
<30 % 0 0 0 13 0 0
Mat ni/dc 0 0 0 1 14 1 Tai nguyd
Dan CLf 1 0 1 0 2 14 in va Ivioi
BCX ngirdi san xuat
94.44 92.86 83.33 92.86 82.35 93.33 trudng | Kj2-
BCX ngddi SIJT dung
100 86.67 93.75 100 87.5 77.78 Thang 10/2015 ^3
hpp cac thdng tin nay chinh la cac quy tac d n dugc xay dung de phan mem d t h i phan biet d c ddi tupng. Trong qua trinh phan loai, cd t h i sQ dyng cae Idp thdng tin chuyen de ngoai dQ lieu viln tham nhu md hinh sd dp cao, ban do thd nhudng, ban do dja chat, ban do SDD.., Viec tfch hpp eae thdng tin ndi trin trong phan loai dinh hudng ddi tUdng dua chQ yeu vao logic md (fuzzy logic). Day chinh la qua trinh xay dung cd sd tri thQc trong phan loai dinh hudng ddi tupng. Vdi CP sd tri thQc nay, mdi dd'i tugng cd the duge phdn loai bang mdt thudt toan khac nhau chU khdng phai bdng mdt thudt toan thdng nhat nhu trong phan loai Pixel-based.
Trong qui trinh phan manh anh, thdng sd ty le rat quan trpng, quyet djnh ddi tupng dupc chilt xua't ed kfch thude Idn hay nhd va chQa dung nhieu hay it d c doi tupng con ben trong. Phan manh theo ky thuat hpp nhat vung tQ dudi len ban dau xem xet tQng pixel nhu mot ddi tQpng rieng biet sau dd tQng dd'i tQpng nhd ke nhau dupc hpp nhat thanh dd'i tupng Idn hon. Su hpp nhat niy dua tren tieu chuin ddng nhlt cue bd, cac cap ddi tupng anh lien k l se dupc gdp lai lam cho dp bat ddng tang len d mUc nhd nha't trong gidi han. Nlu vupt qui gidl han thi qui trinh hpp nhat se ngOng lai. Ket qua cQa qua trinh nay la cac phan manh anh ddng vai trd nhu eac doi tupng anh va chung se dupc phan loai d budc tiep theo.
Phan loai hudng dd'i tuPng nghta la quy cae ddi tupng thanh cac Idp ehuyen de theo d§e tfnh ciia Idp do. Cd hai phuong phap phan loai d day do la phan loai dua tren mau bang thuat toan
lang rieng gan nhlt (nearest neighbour) va phan loai md (fuzzy) dua tren cac ky thuat chQc nang cQa d e thanh phan. Trong phan loai diia tren mau, cae ddi tupng dupc phan loai thdng qua su gidng nhau eCia cac mlu hoae cac manh anh. PhUdng phap nay sQ dung thdng tin phd cQa cac kenh phd d l xle dinh cac Idp, ngoai ra cdn sQ dung cac thdng tin hlnh dang, kien tnic, quan hd cOa d c dd'i tuong lan can de chiet taeh thdng tin. Phan loai md, cac manh anh duac phan loai theo d c chQc nang thanh phan dUa tren tap md cua ddi tupng. Ky thuat nay trp giCip eau true he thdng trong phan cap Idp. Trong cau true phan d p , moi doi tupng anh truy cap thdng tin ve d c ddi tupng anh lan can, ddi tupng anh d p tren va d p dudi trong mpi thdi dilm bang each ket nd'i d c ddi tupng anh theo chieu dpc, truy cap vao quy md va d u true. Phan cap cac ddi tupng anh cho phep dai dien thdng tin anh tai cae dp phan giai khdng gian ddng thdi.
Phuong phap phan loai tiep d n quy tac phan loai dua tren tri thQc chuyen gia nd khdng chi sQ dyng dac tfnh phd eiia anh ma edn sQ dung thdng tin ve hinh dang, kieh thudc, d u true,... va cd t h i sQ dyng cae Idp thdng tin chuyen de ngoai dQ lieu viln tham nhU md hlnh sd dp cao, ban dd thd nhudng, ban dd dja chat, ban dd SDD,... Viec tich hdp cac thdng tin ndi tren trong phan loai dinh hudng ddi tupng chCi yeu vao logic md (fuzzy).
Ket qua
Ban do Idp phQ RNM dupc phan loai theo 4 cap dd dd la:
RNM dp che phCi tren 70%; dp che phli 51-70%; dp ehe phQ 31- 50%; dp che phu dUdi 30%.
Do chinh xic thing t h i dat 89,58%.
Ket luln ' Kit qua eho thiy, sQ dyng
phuong phap phan loai dinh hudng ddi tupng phan loai anh ve tinh VNREDSat-1 d l thanh lap ban do hien trang Idp phii RNM d tl le 1:10000 cho ket qua kha tdt.
Dp chinh xle cQa phuong phap phan loai so vdi sd lieu thUe dja la 89,58%. Hien nay, tai nguydn RNM tai vudn Qudc gia Dat Mui dang phat triln td't, mdt sd dien tich dugc trdng mdi eung bat dau khep tan. Ciing vdi su nd luc trdng rQng ciia ngudi dan va ke hoach bao ve nghiem ngat tai nguyen RNM, se mang lal Ipi fch to Idn dd'i vdi ngudi dan noi day trong viec chdng lai cae tham hpa thien nhien, sdi Id bd biln...
trong bdi d n h BDKH nhU hien nay, gdp phan thuc ddy phit triln KT-XH.
Tai lieu tham khao [1] Kuenzer, C, Bluemel, A., Gebhardt, S., Quoc, T. V., & Dech, S. (2011). Remote sensing of mangrove ecosystems: A review.
Remote Sensing, 3 (5), 878-928.
[2] Clough, B.R (2013), Continuing the journey amongst mangroves. International Society for Mangrove Ecosystems, 2013.
[3] Ajithloimar, T, T Thangaradjou
& L. Kannan et al. (2008), Spectral reflectance properties of man- grove species of the Muthupettai mangrove environment, Tamil Nadu. Journal of Environmental Biology. Vol 29 (5), pp. 785-788.
[4] Nguyen Ngpc Thach, Pham Viet Hda, Nguyen Vu Giang (2013), Dja Thdng tin - Nguyen ly ed ban va Qng dung.
Nha Xua't ban Khoa hpc Tu nhien v l Cdng nghd."
14 Tai nguydn va Moi traong | Ky 2-Th^ng 10/2015
