1

LI CM N

Trc ht, ti xin by t lng cm n chn thnh TS. Nguyn Hi Chu, ngi tn tnh hng dn ti trong sut thi gian lm lun vn tt nghip.

Ti xin cm n cc thy, c gio khoa Cng ngh thng tin, phng Sau i hc, trng i hc Cng ngh - HQG HN ging dy ti trong sut thi gian hc tp ti trng v to iu kin gip ti hon thnh lun vn ny. Cm n cc bn b, ng nghip c v ng vin ti trong sut qu trnh hc tp ti trng.

Tuy c nhng c gng nht nh nhng do thi gian v trnh c hn nn chc chn lun vn ny cn nhiu thiu st v hn ch nht nh. Knh mong nhn c s gp ca thy c v cc bn.

Lun vn thc s ny c thc hin trong khun kh ti nghin cu mang m s QG.09.27, i hc Quc gia H Ni.

H Ni, ngy thng 11 nm 2010

Hc vin

Phng Nam Thng

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LI CAM OAN

Ti xin cam oan kt qu t c trong lun vn l sn phm nghin cu, tm hiu ca ring c nhn ti. Trong ton b ni dung ca lun vn, nhng iu c trnh by hoc l ca c nhn ti hoc l c tng hp t nhiu ngun ti liu. Tt c cc ti liu tham kho u c xut x r rng v c trch dn hp php.

Ti xin hon ton chu trch nhim v chu mi hnh thc k lut theo quy nh cho li cam oan ca mnh.

H Ni, ngy thng 11 nm 2010

Ngi cam oan

Phng Nam Thng

3

MC LC

M U .......................................................................................................... 8 1.1 Khi nim c bn v vin thm........................................................... 12 1.2. Khi nim v mt s c trng ca nh vin thm............................ 12

1.5.1. nh Landsat ............................................................................. 17 1.5.2. nh MODIS ............................................................................. 19 1.5.3. nh VHARR ............................................................................ 22 1.5.4. nh ASTER ............................................................................. 23 1.5.5. nh SPOT ................................................................................ 24 1.5.6. nh IKONOS........................................................................... 26 1.5.7 nh QuickBird .......................................................................... 27 1.5.8 nh SPIN .................................................................................. 27 1.5.9. nh OrbView ........................................................................... 27 1.5.10 nh ARIES.............................................................................. 27

CHNG 2 - PHNG PHP X L NH V TINH.......................... 31 2.1. Phng php gii on nh bng mt: ............................................... 31 2.2 Phn loi nh v tinh bng phng php x l s .............................. 33 2.3 Phng php theo di bin ng ........................................................ 38

2.3.1. Yu cu v to nh nghin cu bin ng ............................... 39 2.3.2. Cc phng php..................................................................... 39

CHNG 3 - XY DNG H THNG QUN L TI NGUYN RNG......................................................................................................................... 42

3.1 Pht biu bi ton. ............................................................................... 42 3.2 C s phn chia rng v qun l rng ................................................ 42

3.2.1. Khi nim v rng.................................................................... 42 3.2.2. Phn chia ranh gii i tng iu tra ..................................... 42 3.2.3. Phn chia kiu trng thi rng.................................................. 42

3.3 Kho st bi ton................................................................................. 45 3.4 Cc cng c h tr m ngun m. ...................................................... 46

3.4.1 Cng c x l nh vin thm Grass. ......................................... 46 3.4.2 H qun tr c s d liu khng gian PostGIS.......................... 51 3.4.3 WebGIS v MapServer ............................................................. 52

3.5. M hnh h thng thng tin qun l ti nguyn rng ........................ 54 3.5.1 M hnh tng quan .................................................................... 54 3.5.2. Phng php xy dng c s d liu qun l ti nguyn rng55

3.6 Th nghim v kt qu........................................................................ 57

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3.6.1 Gii on d liu nh v tinh. ................................................... 57 3.6.2. xy dng c s d liu qun l ti nguyn rng...................... 62 3.6.3. xy dng modun website hin th bn v biu bin ng63

KT LUN .................................................................................................... 76 TI LIU THAM KHO ............................................................................ 78

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CC T VIT TT

Vit tt Tn y - M t

RS Remote sensing Vin thm

GIS Geographic information system - H thng thng tin a l

NDVI Normalized difference vegetation index

GRASS Geographic resources analysis support system

BV Brightness value - gi tr sng ca pixel

IFOV Instantaneous field of view - Trng nhn khng i

FOV Field of view - Trng nhn

DN Digital number - Gi tr ca cc pixel nh

MLC Maximum likelihood classifier - Phn loi gn ng nht

LNN Layered neural networks - Phn loi mng neural

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DANH MC CC HNH V

Hnh 1. Cu trc d liu nh v tinh ................................................................... 14 Hnh 2. Phn mm GRASS................................................................................. 46 Hnh 3. Cng c qun tr pgAdmin III................................................................ 51 Hnh 4. M hnh hot ng ca Mapserver ........................................................ 53 Hnh 5. ng dng WebGIS................................................................................. 53 Hnh 6. M hnh tng quan h thng .................................................................. 54 Hnh 7. Quy trnh cp nht d liu ti nguyn rng ........................................... 56 Hnh 8. nh Landsat TM khu vc nghin cu nm 2007 .................................. 58 Hnh 9. nh huyn Kim Bi - Ha Bnh sau khi ct .......................................... 58 Hnh 10. nh ch s NDVI nm 2007................................................................. 61 Hnh 11. nh phn loi i tng nm 2007...................................................... 62 Hnh 12. M hnh trin khai website qun l ti nguyn rng ........................... 64 Hnh 13. M hnh pht trin website bng mapserver ....................................... 68 Hnh 14. Giao din website theo di ti nguyn rng ........................................ 69 Hnh 15. Kt qu bin ng bng biu ........................................................... 70

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DANH MC CC BNG

Bng 1 Mt s thng s cc knh ph ca nh Landsat TM .............................. 18Bng 2. Mt s thng s cc knh ph nh Landsat ETM+, Landsat -7 ............ 19Bng 3. Mt s thng s v cc knh ph ca nh MODIS ............................... 22Bng 4. Mt s thng s v cc knh ph ca nh NOAA ................................ 23Bng 5. Mt s thng s v cc knh ph ca nh ASTER ............................... 24Bng 6. Mt s thng s v cc knh ph ca nh SPOT-1;-2;-3 ...................... 25Bng 7. Mt s thng s cc knh ph ca nh SPOT-4.................................... 25Bng 8. Mt s thng s cc knh ph ca nh IKNONOS............................... 26Bng 9. Tng hp thng s k thut v ng dng mt s loi nh vin thm ... 30Bng 10. Bng ma trn bin ng gia hai thi im ........................................ 40Bng 11. So snh chi ph bn quyn phn mm (cho mt giy php s dng) .. 49Bng 12. So snh v yu cu phn cng h thng. ............................................. 50Bng 13. Cc phng php phn loi nh bng GRASS.................................... 51Bng 14. Kha phn loi rng nh Landsat ........................................................ 59Bng 15. Kt qu phn loi nh theo ch s NDVI............................................. 62Bng 16. Cu trc bng d liu lp rng ............................................................ 63

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M U Ngy nay khoa hc cng ngh v s pht trin mnh m ca khoa hc k

thut gip con ngi qun l tt hn cc ngun ti nguyn, trong c khoa hc k thut vin thm. K thut vin thm c ng dng vo nhiu lnh vc nghin cu ca Vit Nam mang li nhiu ng dng to ln trong qun l ti nguyn. Trong lnh vc lm nghip, k thut vin thm c s dng thnh lp cc loi bn hin trng rng, phn loi trng thi rng, phn vng trng im chy rng, theo di din bin ti nguyn rng.

Nm 1943, Vit Nam c 14,3 triu ha rng, che ph l 43% nhng n nm 1990 ch cn 9,18 triu ha, che ph rng l 27,2%. Theo cng b ti quyt nh s 1970/Q/BNN-KL-LN ngy 06 thng 7 nm 2006, tnh n 31/12/2005, din tch rng ton quc l 12,61 triu ha, che ph rng l 37%, trong mt rng l nguyn nhn gy ra mt lot cc hin tng nh: l lt, hn hn, mt ma, ko theo l cc tai bin v mi trng lm nh hng rt ln n qu trnh sn xut v sinh hot ca ngi dn. Chnh v vy, nhim v t ra i vi cc c quan chc nng, nhng nh qun l lm nghip l cn pht trin bn vng ngun ti nguyn ny lm c s a ra cc phng n quy hoch, xut cc gii php k thut, kinh t - x hi v nh hng cho vic s dng v qun l bn vng ti nguyn rng.

Hin trng v cng tc qun l rng Vit Nam

nc ta, cc chng trnh theo di din bin ti nguyn rng c tin hnh t nhng nm 1976 vi chng trnh nh gi din bin ti nguyn rng ton quc giai on 1976 - 1990 - 1995, chng trnh iu tra, nh gi v theo di din bin ti nguyn rng ton quc 5 nm cc giai on 1996 2000 v 2000 - 2005 v hin nay ang thc hin chng trnh iu tra, nh gi v theo di din bin ti nguyn rng ton quc giai on 2006 - 2010. Nhng nm trc y iu tra theo di din bin ti nguyn rng ch yu vn da trn vic o v, thnh lp bn hin trng rng bng phng php th cng v vy cng vic ny i hi tn rt nhiu thi gian, cng sc, tin bc, chnh xc khng cao v thng tin thng khng c cp nht v tnh hnh rng v t rng lun bin ng. Trong nhng nm gn y, khi khoa hc cng ngh vin thm pht trin mnh th vic p dng cng ngh vin thm vo lm nghip l rt

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cn thit v k thut vin thm vi kh nng quan st cc i tng cc phn gii ph v khng gian khc nhau, t trung bnh n siu cao v chu k chp lp t mt thng n mt ngy cho php ta quan st v xc nh nhanh chng hin trng lp ph rng, t c th d dng xc nh c bin ng rng v c bit l xu hng ca bin ng. Tuy nhin, cc nghin cu v ng dng cng ngh vin thm trong lm nghip cn rt thiu c bit l cng ngh x l nh s vin thm t ng v bn t ng v hu ht u s dng cc sn phm phn mm x l nh thng mi c gi thnh cao t vi chc n hng trm nghn la M.

Mc tiu ca lun vn

Nhn chung, nhng nghin cu, ng dng cng ngh vin thm trong phn loi v iu tra rng Vit Nam c thc hin t rt sm. Tuy nhin, t trc n nay thnh lp bn rng vn ch yu p dng phng php truyn thng l gii on bng mt, iu tra ngoi nghip, s dng cc phn mm thng mi c gi thnh cao v s dng cc dng t liu vin thm ch yu c phn gii thp hoc trung bnh nn ch c th thnh lp c bn t l thp, khng p ng uc yu cu v chnh xc v tnh cp nht ca bn hin trng rng. Hin nay, cng ngh vin thm ang pht trin mnh, nhiu nh v tinh c phn gii cao cho php thnh lp c cc bn c t l ln. Tuy nhin, cc nghin cu v phng php phn loi thnh lp bn rng; cc dng ch s thc vt c th s dng phn loi rng; cch thnh lp cc dng bn ti nguyn rng nh bn phn b tr lng, sinh khi; nghin cu v phng php nh gi bin ng rng t nh v tinh c phn gii cao bng cc gii php phn mm m ngun m vn cn thiu nhiu v hu nh cha c cc nghin cu nh vy. Chnh v vy, ti mnh dn thc hin ti nh v tinh ng dng trong iu tra, qun l din tch rng nhm a ra gii php thnh lp bn ti nguyn rng t nh v tinh c phn gii cao bng cc cng c m ngun m, tm ra c mt s dng ch s thc vt dng phn loi rng cho nh v tinh c phn gii cao, a ra c quy trnh nh gi bin ng rng t nh v tinh c phn gii cao t gp phn vo vic ng dng vo thc tin sn xut thay th cc phng php truyn thng c bit cho cng tc iu tra, kim k rng trong giai on mi hin nay.

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i tng v nhim v ca lun vn l:

Nghin cu v vin thm - nh v tinh Nghin cu cc phng php x l v gii on nh v tinh Nghin cu v s dng phn mm m ngun m Grass x l v

gii on nh v tinh

Xy dng h thng thng tin qun l ti nguyn rng da trn nh v tinh v h thng thng tin a l

Phng php v ni dung nghin cu c s dng trong sut qu trnh lm lun vn l:

Nghin cu v vin thm, nh v tinh cc c im ca nh v tinh, phn loi nh v tinh, cc phng php t chc d liu ca nh v tinh

Tm hiu cc phng php x l nh v tinh nh hiu chnh bc x, hiu chnh hnh hc, tng cng cht lng nh, bin i gia cc nh, phn loi nh

Tm hiu v phn mm m ngun m GRASS x l v gii on nh v tinh

Xy dng h thng thng tin qun l ti nguyn rng da trn cc gii php GIS ngun m

B cc ca lun vn c trnh by nh sau:

M u: t vn v ngha, tnh cp thit, nhim v v tnh thc tin ca ti.

Chng 1: Tng quan v vin thm v nh v tinh

Gii thiu chung v vin thm Khi nim v t liu nh s Mt s loi nh v tinh

Chng 2: Phng php x l nh v tinh

Phng php gii on nh v tinh Phng php phn loi nh v tinh Phng php nh gi bin ng

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Chng 3: Xy dng h thng thng tin qun l ti nguyn rng

t vn bi ton Cc cng c h tr bng ngun m Xy dng h thng m phng

Kt lun: nh gi kt qu t c, xc nh nhng u, nhc im v nh hng pht trin.

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CHNG 1 - TNG QUAN VIN THM V NH V TINH

1.1. Khi nim c bn v vin thm

Thut ng vin thm (Remote sensing) - iu tra t xa, xut hin t nm 1960 do mt nh a l ngi M l E. Pruit t ra (Thomas, 1999). K thut vin thm l mt k thut a ngnh, n lin kt nhiu lnh vc khoa hc v k thut khc nhau trong cc cng on khc nhau nh:

- Thu nhn thng tin

- Tin x l thng tin

- Phn tch v gii on thng tin

- a ra cc sn phm di dng bn chuyn v tng hp

V vy c th nh ngha Vin thm l s thu nhn v phn tch thng tin v i tng m khng c s tip xc trc tip vi i tng nghin cu. Bng cc cng c k thut, vin thm c th thu nhn cc thng tin, d kin ca cc vt th, cc hin tng t nhin hoc mt vng lnh th no mt khong cch nht nh.

1.2. Khi nim v mt s c trng ca nh vin thm

nh vin thm (v tinh v my bay) l nhng hnh nh thu chp c t mt khong cch ( cao) no trn nhng gii sng khc nhau, bng cc thit b khc nhau.

nh s l mt dng t liu nh ghi nhn cc thng tin vin thm dng s, thng c lu trn cc media in t bng cc bng t, a quay t, Hnh nh thu c s c chia thnh nhiu phn t nh, mi phn t c gi l cc pixel. Mi pixel tng ng vi mt n v khng gian bao ph trn b mt tri t. rng bao ph mt t ca mt pixel c th t vi mt n hng km ty theo loi b cm v c gi l phn gii nh. V tr ca mi pixel c xc nh theo ta hng v ct trn nh tnh t gc trn cng bn tri. Ty theo h thng qut nh m kch thc ca hnh nh (din tch qut trn mt t). V d vi h thng Landsat MSS l 185 x 185km, vi h thng SPOT l 65 x 65km, nh NOAA l 2400 x 2400km [2]

nh v tinh c c trng bi mt s thng s c bn nh sau [2]:

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- Tnh cht hnh hc ca nh v tinh

Trng nhn khng i IFOV (instantaneous field of view) c nh ngha l gc khng gian tng ng vi mt n v chia mu trn mt t. Lng thng tin ghi c trong IFOV tng ng vi gi tr ca pixel.

Gc nhn ti a m mt b cm c th thu c sng in t c gi l trng nhn FOV (field of view). Khong khng gian trn mt t do FOV to nn chnh l b rng tuyn bay.

Din tch nh nht trn mt t m b cm c th phn bit c gi l phn gii khng gian. nh c phn gii khng gian cng cao khi c kch thc pixel cng nh. phn gii khng gian cng c gi l phn gii mt t khi hnh chiu ca 1 pixel tng ng vi mt n v chia mu trn mt t.

- Tnh cht ph ca nh v tinh

Cng mt vng ph mt t tng ng, cc pixel s cho gi tr ring bit theo tng vng ph ng vi cc loi bc sng khc nhau. Do , thng tin c cung cp theo tng loi nh v tinh khc nhau khng ch ph thuc vo s bit dng ghi nhn, m cn ph thuc vo phm vi bc sng.

phn gii ph th hin bi kch thc v s knh ph, b rng ph hoc s phn chia vng ph m nh v tinh c th phn bit mt s lng ln cc bc sng c kch thc tng t, cng nh tch bit c cc bc x t nhiu vng ph khc nhau. phn gii bc x th hin nhy tuyn tnh ca b cm bin trong kh nng phn bit s thay i nh nht ca cng phn x sng t cc vt th.

lu tr, x l v hin th nh v tinh trong my tnh kiu raster, tu thuc vo s bit dng ghi nhn thng tin, mi pixel s c gi tr hu hn ng vi tng cp xm (gi tr sng ca pixel; BV - Brightness Value). S bit dng ghi nhn thng tin c gi l phn gii bc x ca nh v tinh.

- phn gii thi gian ca nh v tinh

phn gii thi gian khng lin quan n thit b ghi nh m ch lin quan n kh nng chp lp li ca nh v tinh. nh c chp vo nhng ngy khc nhau cho php so snh c trng b mt theo thi gian. u th ca phn gii thi gian l cho php cung cp thng tin chnh xc hn v nhn bit s bin

14

ng ca khu vc cn nghin cu. Hu ht cc v tinh u bay qua cng mt im vo khong thi gian c nh (mt t vi ngy n vi tun) ph thuc vo qu o v phn gii khng gian.

D liu nh v tinh c lu tr theo cc khun dng sau y:

Theo kiu BIL (band interleaved by lines): tng hng c ghi theo th t ca s knh, mi hng c ghi tun t theo gi tr ca cc knh ph v sau lp li theo th t ca tng hng, nh vy s to ra cc file d liu nh chung cho cc knh ph.

Theo kiu BSQ (band sequential): l khun dng trong cc knh ph c lu tun t ht knh ny sang knh khc. Ngha l mi nh ng vi mt knh.

Theo kiu BIP (band inteleaved by pixel): mi pixel c lu tun t theo cc knh, ngha l cc knh ph c ghi theo hng v ct ca tng pixel. Sau khi kt thc t hp ph ca pixel ny li chuyn sang t hp ph ca pixel khc.

Hnh 1. Cu trc d liu nh v tinh

1.3. Lch s nghin cu trn th gii

Mc d bc nh u tin c chp nm 1858 nhng mi n thng 9 nm 1887 mi c mt k s Lm nghip ngi c th nghim on c cy rng trn nh hng khng. Theo GS. V Tin Hinh, TS. Phm Ngc Giao [1] th

15

Spurr chia lch s vin thm trong lm nghip th gii thnh ba giai on chnh nh sau:

Giai on th nht: T cui th k 19 n trc chin tranh th gii ln th nht, nh du bng s ra i ca nh hng khng, knh lp th v nhng th nghim ban u v ng dng chng trong lm nghip nh th nghim ca Rudolf Kobsa v Ferdinand Wang (o, 1882), Hugershoff.R (c-1911), Hand Dock (o.1913).

Giai on th hai: T chin tranh th gii ln th nht n cui chin tranh th gii ln th hai. Giai on ny ghi nhn thnh cng ca mt s tc gi mt s nc. Xy dng bn rng t nh hng khng vng Maurice thuc Canada, bn thc vt rng Anh (1924), iu tra tr lng rng t nh hng khng ca M (1940). Th nghim cc phng php o tn, o chiu cao trn nh ca Seely, Hugershoff, Tuy nhin, giai on ny cha xy dng c hon chnh h thng l lun cng nh cc phng php c on nh hng khng.

Giai on th ba: T chin tranh th gii th hai n nay. Cng vi s pht trin khoa hc k thut, vic nghin cu ng dng vin thm ngy cng pht trin rng ri nhiu nc. K thut vin thm pht trin theo chiu hng ngy cng phong ph, tinh vi, chnh xc v cp nht hn vi chng trnh Interkosmos v v tinh Landsat. Song song vi hai h thng trn l h thng trm thu v x l thng tin nhiu quc gia trn th gii nh Canada, Brazin, n , Thi Lan, Trung Quc, Gn y h thng v tinh nh SPOT, nh ADEOS, nh TERRA, nng cao hn na kh nng ng dng ca k thut vin thm trong lm nghip.

1.4. Lch s nghin cu Vit Nam

Trong sut thi gian di trc nm 1945, Vit Nam khng c kh nng thc hin vic iu tra rng. Thi k ny ch c s liu v ti nguyn rng c cng b trong cng trnh "Lm nghip ng Dng" ca P. Maurand v s liu thng c xem l ti liu gc so snh din bin rng Vit Nam t nm 1945 tr v sau.

Nm 1958, vi s hp tc ca CHDC c s dng nh my bay en trng ton sc t l 1/30.000 iu tra rng vng ng Bc [3]. l mt

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bc tin b k thut rt c bn, to iu kin xy dng cc cng c cn thit nng cao cht lng cng tc iu tra rng nc ta. T cui nm 1958, bnh qun mi nm iu tra c khong 200.000 ha rng, s thm c tnh hnh rng v t i ni, lp c thng k ti nguyn rng n gin v v c phn b ti nguyn rng min Bc. n cui nm 1960, tng din tch rng min Bc iu tra c vo khong 1,5 triu ha. min Nam nh my bay c s dng t nm 1959, xc nh tng din tch rng min Nam l 8 triu ha.

Giai on 1970 1975 nh my bay c s dng rng ri xy dng cc bn hin trng, bn mng li vn xut, vn chuyn cho nhiu vng thuc min Bc (V Tin Hinh, Phm Ngc Giao, 1997) [1].

T nm 1981 n nm 1983, ln u tin ngnh lm nghip tin hnh iu tra, nh gi ti nguyn rng trn phm vi ton quc. Trong kt hp gia iu tra mt t v gii on nh v tinh do FAO h tr. Do vo u nhng nm 1980, nh v tinh v nh hng khng cn rt hn ch, ch p ng yu cu iu tra rng mt s vng nht nh m cha c cho ton quc.

T nm 1991 1995 tin hnh theo di din bin ti nguyn rng ton quc v xy dng bn hin trng ti nguyn rng trn c s k tha nhng bn hin trng rng hin c thi k trc nm 1990, sau dng nh v tinh Landsat MSS v Landsat TM c phn gii 30x30m cp nht nhng khu vc thay i s dng t, nhng ni mt rng hoc nhng ni c rng trng mi hay mi ti sinh phc hi [4]. nh v tinh Landsat MSS v Landsat TM t l 1:250.000 c gii on khoanh v trc tip trn nh bng mt thng. Kt qu gii on c chuyn ho ln bn a hnh t l 1:100.000 v c kim tra ti hin trng. Thnh qu thnh lp c: bn sinh thi thm thc vt rng cc vng t l 1:250.000; bn dng t ai cc tnh t l 1:100.000 v cc vng t l 1:250.000.

T nm 1996 2000, bn hin trng rng c xy dng bng phng

php vin thm. nh v tinh s dng l SPOT3, c phn gii 15m x 15m,

ph hp vi vic xy dng bn t l 1:100.000. So vi nh Landsat MSS v

Landsat TM, nh SPOT3 c phn gii cao hn, cc i tng trn nh cng

c th hin chi tit hn. nh SPOT3 vn c gii on bng mt thng nn

17

kt qu gii on vn cn ph thuc nhiu vo kinh nghim ca chuyn gia gii

on v cht lng nh. Kt qu v mt thnh lp bn : xy dng c bn

phn vng sinh thi thm thc vt cp vng v ton quc; bn phn loi

t cp tnh, vng v ton quc; bn hin trng rng cp tnh, vng v ton

quc v bn hin trng rng t l 1:100.000; 1:250.000; 1:1000.000 [2],[ 5].

T nm 2000 2005, phng php xy dng bn trong lm nghip

c pht trin ln mt bc. Bn hin trng rng c xy dng t nh s

v tinh Landsat ETM+. phn gii nh l 30m x 30m. Vic gii on nh

c thc hin trong phng da trn nhng mu kha nh c kim tra

ngoi hin trng. u im ca phng php gii on nh s l tit kim c

thi gian v c th gii on th nhiu ln trc khi ly kt qu chnh thc [6].

Nh vy, tuy khoa hc iu tra rng ra i mun hn so vi nhiu mn

khoa hc khc nhng t c nhng thnh qu nht nh. Song song vi

iu tra mt t, nghin cu th nghim v tng bc ng dng c hiu qu

phng php vin thm trong xy dng cc bn ti nguyn rng. Tuy nhin,

h thng cc bn ti nguyn rng Vit Nam hin nay, do c xy dng ti

cc thi im khc nhau v s dng nhiu ngun thng tin t liu, nhiu

ngun nh, t nh v tinh Landsat MSS, TM, SPOT, Aster, Radar, nh my bay

v h thng phn loi rng rt khc nhau qua cc thi k, nn to ra nhiu

loi s liu khng ng b, gy kh khn cho ngi s dng, c bit trong vic

theo di bin ng v din tch ca rng qua cc thi k.

1.5. Mt s loi nh v tinh ph bin

1.5.1. nh Landsat

Hin nay nh Landsat c nhiu th h vi s lng knh ph v phn

gii khc nhau. Tuy nhin, th h nh Landsat TM c thu t v tinh Landsat-4

v -5 v nh Landsat ETM+ c thu t v tinh Landsat-7 c s dng ph

bin nht. nh Landsat TM gm 6 knh ph nm trn di sng nhn thy v

hng ngoi vi phn gii khng gian 30mx30m v mt gii ph hng ngoi

nhit knh 6, phn gii 120mx120m o nhit b mt. nh Landsat

18

ETM+ ghi ph trn 8 knh cc bc sng ging nh ca nh Landsat TM,

iu khc bit l Landsat ETM+, knh hng ngoi nhit (Thermal) c phn

gii cao hn (60mx60m) v c thm knh ton sc (Pan) vi phn gii khng

gian l 15mx15m.

Knh Bc sng (m) Tn gi ph phn gii

khng gian (m) Lu tr

(bit)

TM1 0,45-0,52 Xanh lam 30 8

TM2 0,52-0,60 Xanh lc 30 8

TM3 0,63-0,69 30 8

TM4 0,76-0,90 Cn hng ngoi 30 8

TM5 1,55-1,75 Hng ngoi sng ngn 30 8

TM6 10,4-12,5 Hng ngoi nhit 120 8

TM7 2,08-2,35 Hng ngoi sng ngn 30 8

Bng 1 Mt s thng s cc knh ph ca nh Landsat TM

nh Landsat c ng dng trong nghin cu ca nhiu lnh vc t nghin

cu hin trng n gim st bin ng v c s dng ph bin nht, vi gi

thnh thp, di y ti thng k nhng ng dng chnh ca nh Landsat

trong nghin cu:

- Knh ph xanh lam (0,45m -0,52m) c ng dng nghin cu ng

b, phn bit thc vt v t, lp bn v rng v xc nh cc i tng khc.

- Knh ph xanh lc (0,52m -0,60m), c dng o phn x cc i

ph lc ca thc vt, xc nh trng thi thc vt, xc nh cc i tng khc.

- Knh ph (0,63m -0,69m), dng xc nh vng hp th chlorophyl

gip phn loi thc vt, xc nh cc i tng khc.

- Knh ph cn hng ngoi (0,76m -0,90m), dng xc nh cc kiu thc

19

vt, trng thi v sinh khi, m ca t.

- Knh hng ngoi sng ngn (1,55-1,75m; 2,08-2,35m), c s dng

xc nh m ca thc vt v t, nghin cu v khong, tch tuyt v

my.

- Knh hng ngoi nhit (10,4m -12,5m), c dng xc nh thi

im thc vt b sc, m ca t v thnh lp bn nhit.

- Knh ton sc 0,52-0,9: vi phn gii thp v gii ph lin tc, nh ca

knh ny c s dng chng ghp vi cc knh nh khc, t o v chnh

xc cc i tng.

Knh Bc sng

(m) Tn gi ph

phn gii khng gian (m)

Lu tr (bit)

ETM+1 0,45-0,52 Xanh lam 30 8

ETM+2 0,52-0,6 Xanh lc 30 8

ETM+3 0,63-0,69 30 8

ETM+4 0,76-0,90 Cn hng ngoi 30 8

ETM+5 1,55-1,75 Hng ngoi sng ngn 30 8

ETM+6 10,4-12,5 Hng ngoi nhit 60 8

ETM+7 2,08-2,35 Hng ngoi sng ngn 30 8

ETM+8 0,52-0,9 Ton sc 15 8

Bng 2. Mt s thng s cc knh ph nh Landsat ETM+, Landsat -7

1.5.2. nh MODIS

nh MODIS c thu t b cm MODIS t trn v tinh Terra (2000) v

v tinh Aqua (2002) c mc ch cung cp d liu v t lin, bin v kh quyn

mt cch ng thi. nh MODIS cung cp d liu nh ton cu 2 ngy mt ln

vi phn gii khng gian l 250m, 500m v 1000m. S knh ph ca MODIS

20

l 36 knh v d liu dng 12 bit, MODIS c c tnh chnh hnh hc v ph.

Phng php chnh ph knh i vi knh c tham chiu cho 36 knh cho ra

sai s pixel hoc cao hn.

D liu ca nh MODIS bao gm cc loi sau:

- D liu nghin cu my vi phn gin 250m x 1000m vo ban ngy v

phn gii 1000m x 1000m vo ban m.

- Nng tng i lu v c tnh quang vi phn gii 5km cho vng

bin v 10km cho t lin vo ban ngy.

- c tnh v my, dy quang hc, nh hng ca bn knh ht, pha

nhit ng hc, my cc vng v tuyn cao, nhit my phn gii 1km-

5km ban ngy v 5km vo ban m.

- Ph thc vt t: iu kin v nng sut c c trng bi ch s thc

vt, c hiu chnh tc ng ca kh quyn, t, phn cc v nh hng theo

hng phn x b mt, kiu ph t v nng sut nguyn thy thc, ch s l

theo din tch v bc x hiu lc mang tnh quang hp b chn.

- Phn x v din tch ph ca tuyt v bng trn bin

- o nhit b mt vi phn gii 1km vo ban ngy v m vi

chnh xc ca hiu chnh tuyt i l 0,3-0,50 ti i dng v mt t.

- Mu ca bin (ph pht x ca i dng c o 5%), da trn d liu

knh ph trong gii sng nhn thy v hng ngoi gn.

- Nng chlorophyl a (vi 35%) t 0,05 n 50mg/m3 cho nc.

- Hunh quang ca chlorophyl (50%) trn b mt vi nng 0,5mg/m3

ca chlorophyla.

Knh ph

Bc sng (m)

phn gii khng gian (m)

Lu tr (bit)

ng dng

1 0,620-0,670 250 12 Khoang ranh gii

21

2 0,841-0,876 250 12 my/t

3 0,459-0,479 500 12

4 0,545-0,565 500 12

5 1,230-1,250 500 12

6 1,628-1,652 500 12

7 2,105-2,155 500 12

Nghin cu c tnh t/my

8 0,405-0,420 1000 12

9 0,438-0,448 1000 12

10 0,493-0,493 1000 12

11 0,526-0,536 1000 12

12 0,546-0,556 1000 12

13 0,662-0,672 1000 12

14 0,673-0,683 1000 12

15 0,743-0,753 1000 12

16 0,862-0,877 1000 12

Nghin cu v mu nc bin, phytopkankton, sinh a ha hc

17 0,890-0,920 1000 12

18 0,931-0,941 1000 12

19 0,915-0,965 1000 12

Nghin cu v hi nc kh quyn

20 3,66-3,84 1000 12

21 3,929-3,989 1000 12

22 4,020-4,080 1000 12

o nhit b mt/my

23 4,433-4,498 1000 12

24 4,482-4,549 1000 12 o nhit kh quyn

25 1,36-1,39 1000 12 My ti

22

26 6,853-6,895 1000 12

27 7,175-7,495 1000 12

28 8,4-8,7 1000 12

29 9,58-9,88 1000 12

Nghin cu v hi nc trong kh quyn

30 9,58-9,88 1000 12 Nghin cu v tng O3

31 10,78-11,28 1000 12

32 11,77-12,27 1000 12

Nghin cu nhit b mt/my

33 13,185-13,485 1000 12

34 13,485-13,785 1000 12

35 13,785-14,085 1000 12

36 14,085-14,385 1000 12

Nghin cu my v cao

Bng 3. Mt s thng s v cc knh ph ca nh MODIS

1.5.3. nh VHARR nh c thu t v tinh NOAA (National Ocenic and Atmospheric

Administration) l v tinh nghin cu kh tng. D liu ca nh c tnh cht ton cu c a v phn gii 4km v c cung cp mt ngy mt ln trn di sng nhn thy v di ph hng ngoi, trng ph mt t ca nh l 2400km. D liu nh NOAA dng trong vic lp bn nhit , tuyt ph, iu tra lt, nghin cu thc vt, phn tch m t trn cp khu vc, lp bn nhin liu, tm kim chy, lp bn bi v bo ct, nghin cu bin i kh hu v cc ng dng trong a cht nh nghin cu ni la, nghin cu mng li sng sui c tnh cht khu vc v cc yu t khc. nh NOAA c s dng nghin cu thc vt trn din rng. Cc knh ph c s dng trong nghin cu nm trong di sng nhn thy (0,58 -0,68m) v knh 2 di sng hng ngoi gn (0,73-1,1m). T hp cc thut ton x l nh cho php nghin cu kh nng nhy cm v iu kin ca thc vt xanh. Mt trong cc t s c xc nh l ch s thc vt NDVI = (ph hng ngoi gn ph nhn

23

thy)/(ph hng ngoi gn + ph nhn thy) v ch s thc vt n gin VI = ph hng ngoi ph nhn thy

Knh ph Bc sng (m) phn gii khng gian

1 0,58-0,68 1,1 km

2 0,72-1,1 1,1 km

3 3,55-3,93 1,1 km

4 10,30-11,30 1,1 km

5 11,30-12,50 1,1 km

Bng 4. Mt s thng s v cc knh ph ca nh NOAA

1.5.4. nh ASTER nh ASTER c thu t b cm ASTER t trn v tinh Terra, ph ca nh l 60km. B cm ASTER c cu thnh t 3 ph h ring r, mi h ph hot ng trn mt h quang ring bit. Cc h ph ny l nhn thy v hng ngoi gn (VNIR), bao gm cc knh ph 1-3, hng ngoi sng ngn (SWIR) gm cc knh ph 4-9 v hng ngoi nhit (TIR) gm cc knh ph 10-14.

Knh ph Bc sng (m) phn gii khng

gian (m) Lu tr (bit)

1 0,52-0,6 15 8

2 0,63-0,69 15 8

3 0,76-0,86 (nhn trc tm) 15 8

3 0,76-0,86 (nhn sau) 15 8

4 1,60-1,70 30 8

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5 2,145-2,185 30 8

6 2,185-2,225 30 8

7 2,235-2,285 30 8

8 2,295-2,365 30 8

9 2,36-2,43 30 8

10 8,125-8,475 60 12

11 8,475-8,825 60 12

12 8,925-9,275 60 12

13 10,25-10,95 60 12

14 10,95-11,65 60 12

Bng 5. Mt s thng s v cc knh ph ca nh ASTER

Cc ng dng chnh ca nh ASTER l: Quan st t lin, bin, mt tuyt, qu trnh my; Nghin cu v ng lc v cu trc ca thc vt; Nghin cu v cn bng phng x ca kh quyn, my v s m rng v c tnh tng i lu; Xc nh nng v bin ng ca cc kh nh knh; Nghin cu v ni la v cc qu trnh b mt ca tri t.

1.5.5. nh SPOT nh SPOT c thu t b cm HRG t trn v tinh SPOT (Systeme

Pour Lobservation de La Terre) do trung tm nghin cu khng gian ca Php (CNES French Center National detudies Spatiales) thc hin c s tham gia ca B v Thy in. nh SPOT tng i a dng v di ph v phn gii khng gian t thp, trung bnh n cao (5m-1km), trng ph mt t ca nh SPOT cng tng i a dng t 10km x 10km n 200km x 200km. nh SPOT c th thu nh ca tng ngy, thng vo 11h sng.

Tn band ph Di ph

(m) phn gii

(m) che ph

mt t (km) Lu tr (bit)

25

Ton sc 0,51-0,73 10 60 x 60 8

1 0,50-0,59 20 60 x 60 8

2 0,61-0,68 20 60 x 60 8

3 9,79-0,89 20 60 x 60 8

Bng 6. Mt s thng s v cc knh ph ca nh SPOT-1;-2;-3

nh SPOT thuc th h v tinh SPOT-1,-2,-3 nh c hai dng l: nh ton sc (panchromatic) c phn gii khng gian l 10m x 10m v nh a ph vi phn gii khng gian l 20m x 20m.

nh SPOT thuc th h v tinh SPOT-4, c thu t thit b b cm HRVIR l nh thu lin tc trong di ph nhn thy v hng ngoi v c phn gii 20m x20m.

Knh ph Tn ph Di ph

(m) phn gii

khng gian (m) Lu tr

(bit)

Xanh lam 0,43-0,47 20 8

Knh 1 Xanh lc 0,50-0,59 20 8

Knh 2 0,61-0,68 20 8

Knh 3 Cn hng ngoi 0,79-0,89 20 8

Knh 4 Hng ngoi trung 1,58-1,75 20 8

1 knh ton sc Ph n 0,61-0,68 10 8

Bng 7. Mt s thng s cc knh ph ca nh SPOT-4

i vi cc nh SPOT thuc th h SPOT-5 c thu t b cm c phn gii hnh hc cao HRG (High Resolution Geometric) l 5m thay cho 10m knh ton sc v 5m cho cc knh xanh, , cn hng ngoi v 20m i vi knh hng ngoi trung. Th h v tinh SPOT-5 cn trang b thit b

26

ring o thc vt trong di ph nhn thy v cn hng ngoi vi phn gii khng gian 1000mx100m v nh c cp nht hng ngy. Hin nay nh SPOT c ng dng trong nhiu lnh vc nh: nghin cu hin trng s dng t, khai khong trong a cht, thnh lp bn t l 1:30.000 n 1:100.000, nghin cu v thc vt cp khu vc, nh SPOT c th ghi phn x ph ca ton mt t vi s khc bit v d liu, phn gii cao v c kh nng nhn ni, nhy cm v ph hng ngoi cho thc vt.

1.5.6. nh IKONOS

Tn knh Tn ph Bc sng

(m) phn gii

(m)

Lu tr

(bit)

Knh 1 Xanh lam 0,45-0,52 4 11

Knh 2 Xanh lc 0,51-0,60 4 11

Knh 3 0,63-0,70 4 11

Knh 4 Hng ngoi 0,76-0,85 4 11

Knh ton sc Ton sc 0,45-0,90 1 11

Bng 8. Mt s thng s cc knh ph ca nh IKNONOS

nh IKONOS c thu t v tinh to nh v tr phn gii siu cao IKONOS c phng ln qu o cn cc vo ngy 24 thng 9 nm 1999 ti cao 682 km, ct xch o vo 10:30 pht sng. lp li qu o ti mt im trn tri t l sau 11 ngy, rng ca nh trn mt t l 11km, v ph l 11 x 11 km. nh c trn 4 knh a ph vi phn gii l 4 m v knh ton sc phn gii l 1m. Cc knh a ph v knh ton sc kt hp cho php to nh c phn gii 1m gi mu. D liu s c cu trc l 11 bit (2048 mc xm). IKONOS c th nhn vo vt, vo i tng v c nh vi giy v c th hng theo i tng kho st. Cc thng s k thut ca IKONOS c nu trong bng.

27

1.5.7. nh QuickBird nh QuickBird l nh c phn gii khng gian cao nht hin nay

cho ra knh ton sc c phn gii l 0.61 m v phn gii ca cc knh a ph l 2.44 m, trng ph mt t ca nh l 16.5km x 16.5km. QuickBird cho nh phn gii 0,7 m ghp knh ton sc t hp vi knh hng ngoi. Vi phn gii cao nh QuickBird c s dng trong nhiu lnh vc cn chnh xc ln, nh quy hoch s dng t, xc nh chnh xc cc i tng, thnh lp bn giao thng, Hin nay nh QuickBird c s dng ph bin vo cc lnh vc dn s, an ninh, qun l mi trng.

1.5.8. nh SPIN nh SPIN-2 c thu t v tinh SPIN (Space Information Meter)

ca Nga, nh c thu t cao 220km, cc bc nh chp c t l 1:200.000 vi tng cnh chp ph mt din tch c kch thc l 40km x 160km, kch thc trung bnh ca pixel nh trn mt t l 1,56m. nh SPIN ch yu c dng vo mc ch qun s.

1.5.9. nh OrbView nh OrbView thuc th h v tinh OrbView-4 c 200 knh ph, vi

phn gii khng gian l 8m, lp li ca mt im trn mt t l 3 ngy, c ng dng nghin cu cc kiu vt cht trn mt t. D liu ca nh OrbView ch yu phc v cho qun i M trong vic gim st thng tin trn mt t.

1.5.10. nh ARIES nh ARIES (Australia Resource Information and Environmental

Satellite) l loi nh siu ph vi s knh ph l 105 knh trn di sng t 0,49 n 0,25km, cho phn gii l 30m vi ph mt t l 15km x 15km, nhn lp mt im l 7 ngy, knh ton sc c phn gii l 10m. Mc ch ca nh ny l dng vo vic khai khong, ngoi ra cn c dng vo mc ch nghin cu nng nghip, rng, t m v iu tra mi trng.

Qua vic thng k cc thng s k thut ca mt s loi nh vin thm ang c s dng trong nhiu lnh vc nghin cu ca Vit Nam, ti nhn thy c nhiu loi nh v tinh c th ng dng vo lnh vc nghin cu ca ti. Tuy nhin thun li cho vic so snh cc nh v tinh, ti tng

28

hp mt s thng s k thut v ng dng ch yu ca mt s nh v tinh m ti c th s dng.

Loi nh Thng s k thut ng dng trong phn

loi v theo di bin ng

1. nh a ph c phn gii thp (Multispectral Low Resolution Sensors

MODIS

phn gii thp (250m 1000m); Trng ph 2330km; Chu k bay chp 1-2 ngy; nh c t 2000 (v tinh Terra) hoc 2002 (v tinh Aqua) n nay.

AVHRR

phn gii thp 1km t cc v tinh NOAA; Trng ph 2400km x 6400km; nh c t 1980 n nay.

- Quy m bn : ton cu, lc a hoc quc gia

- Phn loi lp ph v theo di bin ng ca lp ph (vd: rng, th, mt nc...)

2. nh a ph c phn gii trung bnh (Multispectral Moderate Resolution Sensors)

Landsat TM

phn gii thp n trung bnh (30m -120m); Trng ph 185km x 185km; Chu k bay chp 16 ngy; nh t nm 1982 n nay;

- Quy m bn : khu vc

- Phn loi v theo di bin ng ca lp ph

Landsat ETM+

(Landsat 7)

phn gii thp n trung bnh (15m - 120m); Trng ph 185km x 185km. Chu k bay chp 16 ngy; nh c t 1999 n nay;

ASTER

phn gii trung bnh (15-90m) vi 14 knh ph t bc sng nhn thy ti hng ngoi gn; Trng ph 60km x 60km. nh c t nm 2000 n nay.

- Quy m bn : khu vc

- Phn loi v theo di bin ng ca lp ph, xc nh mt s i tng c th nhn bit r.

29

3. nh a ph c phn gii cao (Multispectral High-spatial Resolution Sensors Hyperspatial )

SPOT

phn gii cao n trung bnh, t 2.5m n 20m (vi SPOT VGT l 1km); Trng ph 60km x 60km (vi SPOT VGT l 1000km x 1000 km); SPOT 1, 2, 3, 4 v 5 c nh tng ng t 1986, 1990, 1993, 1998 v 2002. D liu nh cung cp trong 1-2 ngy Hin nay SPOT 1 v 3 ngng cung cp nh.

- Quy m bn : a phng, khu vc (hoc ln hn i vi SPOT VGT)

- Phn loi rng cp qun x hoc cc loi c th

- ng dng tt trong vic theo di bin ng ca lp ph.

IKONOS phn gii rt cao (1m 4m); Trng ph 11km x 11km; Chu k bay chp 3-5ngy.

QuickBird

phn gii rt cao (0.6m 2.4m); Trng ph 16.5km x 16.5km. Chu k bay chp 1-3.5 ngy tu thuc vo v .

- Quy m bn : khu vc, a phng hoc nh hn

- Phn loi rng chi tit cp qun x hoc cc loi c th;

- Thng c s dng kim tra kt qu phn loi t cc ngun khc.

4. nh siu ph (Hyperspectral Sensors)

AVIRIS

nh siu ph vi 224 knh t bc sng nhn thy ti sng ngn hng ngoi; Tu thuc vo v ca v tinh m nh c phn gii > 1m, trng ph > 1km.

- Quy m bn : khu vc, a phng hoc nh hn;

- Phn loi rng chi tit cp qun x hoc cc loi c th; nh ch chp theo yu cu 1 ln, v vy khng thch hp vi theo di din bin ca cc i tng.

30

OrbView

nh c 200 knh ph, vi phn gii khng gian l 8m, lp li ca mt im trn mt t l 3 ngy. nh c t nm 2001.

- Quy m bn : khu vc hoc a phng

- ng dng nghin cu cc kiu vt cht trn tri t

ARIES

nh c s knh ph l 105 knh trn di sng t 0,49 n 0,25m, cho phn gii l 30m vi ph mt t l 15km x 15km, nhn lp mt im l 7 ngy.

- Quy m bn : khu vc hoc a phng

- ng dng trong vic khai khong, nghin cu nng nghip, rng, t m v iu tra mi trng

Bng 9. Tng hp thng s k thut v ng dng ca mt s loi nh vin thm

31

CHNG 2 - PHNG PHP X L NH V TINH

X l nh v tinh l qu trnh chit tch cc thng tin theo nh tnh cng nh nh lng t nh da trn cc tri thc chuyn ngnh hoc kinh nghim ca ngi gii on. Vic tch cc thng tin trong nh vin thm c th phn thnh 5 loi: Phn loi a ph, pht hin bin ng, chit tch cc thng tin t nhin, xc nh cc ch s, chit tch cc thng tin t nhin, xc nh cc i tng c bit [7]. X l thng tin vin thm c hai phng php c bn l: phn tch bng mt v x l s.

2.1. Phng php gii on nh bng mt:

Gii on bng mt l s dng mt ngi cng vi tr tu tch chit cc thng tin t t liu vin thm dng hnh nh. Trong vic x l thng tin vin thm th gii on bng mt (visual interpretaion) l cng vic u tin, ph bin nht v c th p dng trong mi iu kin c trang thit b t n gin n phc tp. Vic phn tch nh bng mt c th c tr gip bng mt s thit b quang hc t n gin n phc tp nh knh lp, knh lp th, knh phng i, knh t hp mu,.. nhm nng cao kh nng phn tch ca mt ngi. Phn tch nh bng mt l cng vic c th p dng mt cch d dng trong mi iu kin v c th phc v cho nhiu ni dung nghin cu khc nhau: nghin cu lp ph mt t, nghin cu rng, th nhng, a cht, a mo, thu vn, sinh thi, mi trng (H Vn Hi, 2002) [8]...

Nhn chung, c th chia cc yu t gii on thnh 8 nhm chnh sau:

1 - Kch thc: Kch thc ca i tng ty thuc vo t l nh, kch thc c th c xc nh nu ly kch thc o c trn nh nhn vi nghch o t l ca nh (cn phi chn mt t l nh ph hp gii on).

2 - Hnh dng: L c trng bn ngoi tiu biu cho i tng v c ngha quan trng trong gii on nh. Hnh dng c trng cho mi i tng khi nhn t trn cao xung c coi l du hiu gii on nh quan trng (rung thng c dng hnh vung hay ch nht, khu vc chung c cao tng khc vi nh ring l, ).

3 - Bng rm: Khi ngun pht nng lng (mt tri hay radar) khng nm ngay trn nh u hoc trong trng hp chp nh xin s xut hin bng ca i tng. Cn c theo bng ca vt th xc nh c chiu cao

32

ca chng, trong nh radar bng rm l yu t gip cho vic xc nh a hnh v hnh dng mt t. Tuy nhin, bng rm trong nh v tinh quang hc thng lm gim kh nng gii on i vi khu vc nhiu nh cao tng, rt kh khn trong vic xc nh din tch ca vt th.

4 - m nht: L tng hp nng lng phn x bi b mt ca i tng. Mi vt th c th hin bng mt cp sng nht nh t l vi cng phn x nh sng ca n (nh en trng bin thin t trng n en tuyn, nh mu th tone nh s cho m nht mu phn bit cc vt th khc nhau). m nht ca nh l yu t rt quan trng v c bn trong vic gii on nh.

5 - Mu sc: L mt yu t rt thun li trong vic xc nh chi tit cc i tng. V d, cc kiu loi thc vt vt c th c pht hin d dng qua mu sc (ngay c cho nhng ngi khng c kinh nghim). Trong gii on nh khi s dng nh hng ngoi mu, cc i tng khc nhau s c tone mu khc nhau, c bit s dng nh a ph t hp mu. Ty theo mc tiu gii on, vic chn la cc knh ph t hp mu s hin th c tt nht cc i tng m ngi gii on quan tm.

6 - Cu trc: L tn s lp li ca s thay i cu trc tone nh cho mt khu vc c th trn nh quang hc. Cu trc cn l mt tp hp ca nhiu hnh mu (i tng) nh phn b thng theo mt quy lut nht nh trn mt vng nh m trong mt mi quan h vi i tng cn nghin cu, cc i tng nh ny s quyt nh i tng c cu trc l mn hay sn si.

7 - Hnh mu: Lin quan n vic sp xp ca cc i tng v mt khng gian v mt ngi gii on c th phn bit c. y l dng tng ng vi vt th theo mt quy lut nht nh, ngha l s lp li theo trt t c th ca tone nh hay cu trc s to ra s phn bit v ng thi c th nhn bit c hnh mu. Hnh mu cung cp thng tin t s ng nht v hnh dng ca chng.

8 - Mi lin quan: S phi hp tt c cc yu t gii on, mi trng xung quanh hoc mi lin quan ca i tng nghin cu vi cc i tng khc s cung cp mt thng tin gii on quan trng gim nh vic xc nh chnh xc i tng.

Kha gii on nh

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Kha gii on l chun gii on cho i tng nht nh bao gm tp hp cc yu t v du hiu do nh gii on thit lp, nhm tr gip cho cng tc gii on nhanh v t kt qu chnh xc thng nht cho cc i tng t nhiu ngi khc nhau [2].

Kt qu gii on ch yu ph thuc vo kha gii on, thng thng kha gii on c thnh lp da trn nhng vng nghin cu th nghim c iu tra k lng. Bng cch s dng kha gii on, ngi gii on c th pht trin m rng v phn tch cho nhiu vng khc trn c s cng mt loi t liu cng nh cng ma v thi gian chp nh do gip cho cng tc gii on nhanh hn v m bo c tnh thng nht trong qu trnh gii on.

2.2. Phn loi nh v tinh bng phng php x l s

Hiu chnh bc x Do nhiu nguyn nhn khc nhau nh: do nh hng ca b cm bin

hoc c th do nh hng ca a hnh v gc chiu ca mt tri hoc do nh hng ca kh quyn, lm nh hng rt ln n cht lng nh thu c. m bo nhn c nhng gi tr chnh xc ca nng lng bc x v phn x ca vt th trn nh v tinh, cn phi thc hin vic hiu chnh bc x nhm loi tr cc nhiu trc khi s dng nh [2].

Hiu chnh hnh hc nh Bn cht cc bin dng hnh hc ca nh c hiu nh l s sai lch

v tr gia ta nh thc t (o c) v ta nh l tng c to bi mt b cm bin c thit k hnh hc chnh xc v trong iu kin thu nhn l tng, nhm loi tr sai s gia ta nh thc t v ta nh l tng cn phi tin hnh hiu chnh hnh hc. Nguyn nhn gy ra bin dng hnh hc c th l do ni sai tc l do tnh cht hnh hc ca b cm hoc do ngoi sai gy ra bi v th ca vt mang v hnh dng ca vt th. Ngoi ra s bin dng ca a hnh cng gy nn bin dng hnh hc ca nh trong nh hng do s thay i a hnh gy nn bin dng tng dn t tm nh ra cc bin, cc im trn mt t c cao thp hoc cao hn cao chun tham chiu (trong lc chp nh) u b bin dng. Chnh v vy, hiu chnh hnh hc cn phi c thc hin loi tr s bin dng hnh hc ca nh. Bn cht ca hiu chnh hnh hc l xy dng mi quan h gia h ta nh v

34

h ta quy chiu chun (c th l h ta mt t vung gc hoc a l) da vo cc im khng ch mt t, v th ca sensor, iu kin kh quyn, hiu chnh hnh hc nh v tinh cn phi da trn bn cht ca s bin dng c phng php hiu chnh cho ph hp [2].

Tng cng cht lng nh Tng cng cht lng nh c th c nh ngha l mt thao tc lm

ni bt hnh nh sao cho ngi gii on nh d c, d nhn bit ni dung trn nh hn so vi nh gc. Phng php thng c s dng l bin i cp xm, bin i histogram, bin i tng phn, lc nh, t hp mu, chuyn i gia 2 h RGB v HIS , [2].

Bin i gia cc nh Bin i gia cc nh lin quan n vic to ra nh mi t vic x l

cc nh a ph hoc a thi gian bng cc thut ton c p dng trn ngun nh gc c. Ty thuc vo yu cu thc t ng dng, cc knh ca nh a ph hoc cc nh a thi gian (chp thi im khc nhau) c phi hp rt a dng to nh mi nhm nhn mnh cc i tng c quan tm trn nh hoc cho php chit tch c c tnh ca cc i tng nhanh chng v chnh xc hn so vi vic thc hin trn ngun nh gc. Phng php bin i gia cc nh thng c s dng l phng php bin i s hc, trong phng php ny c 2 phng php thng c s dng l bin i to nh da trn ch s thc vt NDVI v bin i to nh t s [2].

- Bin i to nh da trn ch s thc vt: To nh da trn ch s thc vt NDVI l dng c bit ca nh t s

c xut u tin bi Rouse v cc cng s nm 1973, nhm nhn mnh vng thc ph cho trn nh mi. Cc ch s thc vt nh NDVI (Normalized Differenct Vegetation Index) v EVI (Enhanced Vegetation Index) [22] cng c xem nh l mt thut ton phn loi lp ph thc vt. Cc ch s ny c tnh ton trn cn c, thc vt thng phn x mnh vi bc sng hng ngoi gn v hp th mnh vi bc sng mu . S tng phn gia 2 knh ph ny c s dng tnh ton ch s thc vt. Cc ch s thc vt thng c lin h rt cht vi hot ng ca qu trnh quang hp. Ch s NDVI c nhiu tc gi s dng trong phn tch bin ng ca lp ph rng trn cc nh v tinh a thi gian [23]. Cc nhm thc vt, hoc kiu

35

rng cng c th nhn bit c qua vic nghin cu phn b gi tr NDVI trn nh (Lenney, 1996) [22].

- Bin i to nh t s: Php chia c s dng kh rng ri trong vic to nh t s nhm loi

tr bng rm do nh hng ca a hnh, tch c tnh cc yu t a cht, nhn mnh cc i tng cn quan tm nh vng ph thc vt hay chnh lch nhit , Bng cch chn 2 knh thch hp ca nh a ph, chia gi tr sng tng ng vi tng pixel ca 2 knh nh gc ny nhn c gi tr sng pixel ca nh mi c gi l nh t s [2].

Phn loi nh Phng php phn loi nh c thc hin bng cch gn tn loi (loi

thng tin) cho cc khong cp sng nht nh (loi ph) thuc mt nhm i tng no c cc tnh cht tng i ng nht v ph nhm phn bit cc nhm vi nhau trong khun kh nh. Ty thuc vo s loi thng tin yu cu, loi ph trn nh c phn thnh cc loi tng ng da theo mt lut quyt nh no c xc nh trc. C 2 hnh thc phn loi nh l phn loi c kim nh (Suppervised Classification) v phn loi khng kim nh (Unsuppervised Classitication) c hai phng php phn loi ny u c phn loi da trn nguyn l l cc ch tiu phn loi c xc lp da trn c trng ph ca cc vng mu v dng lut quyt nh thch hp gn nhn pixels ng vi tng vng ph c th [2].

- Phn loi khng kim nh: L vic phn loi thun ty theo tnh cht ph m khng bit r tn hay

tnh cht ca lp ph v vic t tn ch l tng i da vo vic phn lp ph (Chistens).

- Phn loi c kim nh: L phn chia mt cch c kim nh cc gi tr DN (Digital Number)

ca cc pixel nh theo tng nhm n v lp ph mt t bng vic s dng my tnh v cc thut ton. thc hin vic phn loi c kim nh, phi to c cha kho phn tch ph ngha l tm c tnh cht ph c trng cho tng i tng lp ph mt t v t tn cho chng. Cng vic xc nh cha kho phn tch ph c gi l to cc vng mu (hay vng kim tra trainning areas). T cc vng ny, cc pixel khc trong ton nh s c xem

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xt v sp xp theo nguyn tc ging nht (Look must like) a v cc nhm i tng c t tn.

Trong phn loi c kim nh c mt s phng php thng c s dng l: phn loi hnh hp (Parallelpiped Classification), phn loi theo khong cch nh nht (Minimum distance Classification), phn loi hm xc sut cc i (Maximum Likelihood Classification), .

+) Phn loi hnh hp (Parallelpiped Classification): L phng php phn loi n gin nht, trn mi trc khng gian ph tng loi c xc nh da trn gi tr max v min ng vi tng loi. Cc gi tr max v min ny s xc nh hnh hp trong khng gian c trng (nn gi l phn loi hnh hp), s hp ph thuc vo s loi cn xc nh. Phng php ny cn c gi l Paralleleiped classifier v cc cnh i din ca hp l song song nhau. Cc pixel c gi tr nm trong khng gian gii hn bi cc min xc nh (hp) trn trc ph nh vy s c phn loi vo loi tng ng, nhng pixel c gi tr nm ngoi tt c cc hp s c gn nhn l loi khc (ngoi cc loi c quan tm).

+) Phn loi theo cy quyt nh (Decision Tree - DT): L phng php phn loi da trn c s phn cp. Ngi phn loi s phi xut pht t vic nh gi kh nng phn tch cc i tng da trn tri thc chuyn gia kt hp vi c tnh ph ca vng mu to dng ra s phn loi. Trong thc t, khng c thut ton tng qut no cho phng php phn loi ny, do tng cy quyt nh hay lut phn loi thng c thit k bi chuyn gia sao cho kh nng phn bit gia cc loi l cao nht.

+) Phn loi khong cch nh nht (Minimum distance Classification): Phng php ny c s dng phn loi i tng trong khng gian ph a chiu. Khong cch gia cc pixel nh thc o nh gi s thuc v mt lp no ca pixel ang kho st. Cc khong cch thng s dng trong vin thm l: khong cch clit, khong cch clit chun ha, khong cch Mahalanobis. Vic la chn khong cch no l ty thuc vo tnh cht v tng iu kin c th. y l mt phng php phn loi kh nhanh. Gi tr ph ca pixel gn vi gi tr ph trung bnh ca lp mu. Tuy nhin, phng php ny cng cha tht s chnh xc v cha tnh n s bin thin ca cc lp phn loi.

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+) Phn loi gn ng nht (Maximum Likelihood Classifier - MLC) Phng php phn loi gn ng nht MLC c p dng kh ph bin v c xem nh l thut ton chun so snh vi cc thut ton khc c s dng trong x l nh vin thm. MLC c xy dng da trn c s gi thuyt hm mt xc sut tun theo lut phn b chun. Mi pixel c tnh xc sut thuc vo mt loi no v n c ch nh gn tn loi m xc sut thuc vo loi l ln nht. Mc d phng php phn loi ny cho kt qu chnh xc nhng khi s dng cn phi ch mt s im nh sau:

o S lng pixel khi c chn cho vng mu phi ln ng vi tng loi, cc gi tr trung bnh cng nh ma trn phng sai - hip phng sai tnh cho mt loi no c gi tr ng vi thc t.

o Ma trn nghch o ca ma trn phng sai - hip phng sai s khng n nh trong trng hp c s tng quan cao gia cc knh ph gn nhau. nng cao chnh xc phn loi, cn phi gim s knh ca nh v tinh bng cch phn tch thnh phn chnh (PCA).

o MLC ch cho php phn loi ti u trn c s gi thuyt hm mt xc sut tun theo lut phn b chun. Trong trng hp hm phn b ca d liu nh khng tun theo lut phn b chun th khng nn s dng phng php ny.

+) Phn loi mng neural LNN (Layered Neural Networks): Nhng nm gn y, mng neural a lp LNN c nghin cu p dng trong lnh vc nhn dng v x l nh s. Cu trc ca mng neural a lp bao gm mt lp nhp, mt lp xut v mt s lp trung gian. S lp trong lp nhp v xut c nh v c xc nh bi tng ng dng c th. S nt trong lp trung gian (lp n) c th thay i v c quyt nh bi ngi s dng. Tn hiu i t lp nhp v xut thng qua tuyn ni gia cc neuron v mi tuyn ni c gi tr trng s tng ng gi l trng s ni. V neuron nhp ch nhn v truyn tn hiu, cn cc neuron lp n v xut u s dng cng hm hot tnh. Do , khi cu trc n nh, xut ca mng neuron a lp c xc nh bi gi tr ca cc trng s ni. Hun luyn kh nng nhn bit ca LNN l qu trnh iu chnh cc gi tr trng s, sao cho gi tr xut ca LNN ph hp vi nhng gi tr mong mun. ng dng LNN trong phn loi nh v tinh, s neuron ca lp nhp tng ng vi s knh ph ca nh, s neuron

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ca lp xut tng ng vi s loi cn xc nh v s neuron ca lp n s do nh phn tch quyt nh. Phng php LNN trong phn loi c gi l phng php phi tham s c kh nng ng dng rt tt trong x l nh vin thm. LNN thng c s dng khc phc nhc im ca thut ton MLC nhm nng cao chnh xc phn loi trong nhng trng hp nh v tinh c s tng quan cao gia cc knh ph. Vn kh khn cho ngi s dng l vic chn m hnh thch hp LNN nhn bit b d liu mu sn c phn loi chnh xc cc d liu cha bit trong phn loi nh vin thm.

+) Phn loi m (fuzzy classification):

L lun m l mt phng php ton hc nhm lng ha cc pht biu m h. tng c bn l thay th hai pht biu l lun nghim ngt c v khng bi dy lin tc [01], m 0 ngha l khng chnh xc v 1 l chnh xc. Mi gi tr gia 0 v 1 i din mt pht biu t nhiu chc chn ca chnh xc v khng chnh xc. V vy, cc h phn loi m thch hp tt vi vic x l hu ht cc vn trong tch thng tin vin thm. Do cc loi thuc lp ph mt t kh a dng nn vic ch nh chnh xc pixel n tng loi c th l khng n gin. Mc tiu phn loi l tm s ph hp 1 - 1 gia thng tin ph ca pixel v thng tin loi tng ng (da vo b d liu mu) v mong mun s phn loi t s chnh xc cao nht. Tuy nhin, trong thc t, nhiu trng hp gp phi bi cc phng php phn loi truyn thng l s khng phn bit r rng gia chnh xc v khng chnh xc.

2.3. Phng php theo di bin ng

Theo di bin ng l yu cu cp thit ca nhiu lnh vc iu tra, qun l c ng dng rng ri trong cc ngnh ni chung v qun l ti nguyn ni ring.

Pht hin bin ng l qu trnh nhn dng s khc bit v trng thi ca mt i tng hay hin tng bng cch quan st chng ti nhng thi im khc nhau. S dng nh v tinh pht hin bin ng l pht hin nhng s thay i v lp ph pha trn b mt t da trn s thay i v gi tr bc x. Tuy nhin s thay i v bc x do s thay i lp ph mt t phi ln so vi nhng s thay i v bc x gy ra bi cc yu t khc. Nhng yu t khc nh: S khc bit v iu kin kh quyn, s khc bit v

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gc mt tri v s khc bit v m ca t. gim nh hng ca cc yu t chng ta s dng bng cch chn d liu thch hp, v cc phng php tin x l nh tng cng cht lng nh.

nghin cu bin ng th cn phi xy dng nh bin ng v i tng nghin cu.

2.3.1. Yu cu v to nh nghin cu bin ng

- T liu ca cng mt khu vc

- T liu phi l cng loi hoc c tnh cht tng t nh nhau

- nh phi c chp trong cc thi gian khc nhau

2.3.2. Cc phng php

Nhiu phng php pht hin bin ng s dng nh v tinh c xut nh: so snh cc phn loi lp ph; phn loi nh a thi gian; nh hiu hoc nh chia; s khc bit v ch s thc ph; phn tch thnh phn chnh.

Cc phng php chnh l:

- To nh bin ng t nh gc theo tng knh ph: Phng php so snh cc gi tr DN ca tng knh gia hai thi im chp nh khc nhau, bng cch to nh hiu s ca hai knh :

DN (1, 2) = DN (1) DN (2)

trong :

DN (1) - gi tr DN ca pixel trong nh chp thi gian (1),

DN (2) - gi tr DN ca pixel trong nh chp thi gian (2),

DN (1, 2) - gi tr DN ca pixel nh bin ng gia thi gian 1- 2,

Nu DN = 0. Khng bin ng, DN>0 bin ng theo hng 1, DN

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thuc vo vic xc nh ngng phn chia. Trong thc t, vic xc nh ngng phn chia chnh xc khng l vn n gin.

- Phng php da vo vng mu: D trn nghin cu thc nghim vng mu trn tp cc knh a ph cc thi im khch nhau pht hin s bin ng v khng bin ng. Tuy nhin chn c vng mu ph hp xc nh c l bin ng v khng bin ng cn phi nghin cu k lng.

- Phng php nh gi bin ng sau phn loi: nh gi bin ng theo phng php ny th t kt qu ca phng php nghin cu phn loi rng ta s phn loi 2 nh 2 thi im khc nhau theo phng php phn loi chnh xc nht sau s em 2 nh sau phn loi chng ph ln nhau c bn bin ng. p dng phng php ny c kt qu chnh xc vic phn loi phi thc hin theo cng h thng phn loi v cng phng php. Nguyn tc nh gi bin ng ca hai nh phn loi l da vo bng ma trn bin ng. Bng ma trn bin ng l mt bng cho (Crossing image) t hai nh phn loi.

nh thi gian a

L1 L2 L3 L4

L1 L11 L21 L31 L41

L2 L12 L22 L32 L42

L3 L13 L23 L33 L43

L4 L14 L24 L34 L44

Bng 10. Bng ma trn bin ng gia hai thi im

Trn ma trn, theo ct v theo hng l tn cc i tng c phn loi theo 2 thi im a v b. Theo ng cho l cc i tng khng c s bin ng, cn li l nhng bin ng chi tit ca tng i tng. V d: L23 l i tng L2 ca thi im a bin thnh i tng L3 ca thi im b.

- Phng php nh gi bin ng c s kt hp gia vin thm v GIS: nh gi bin ng theo phng php ny th ta cn thnh lp bn hin trng ti hai thi im cn nh gi sau chng xp 2 lp bn hin trng ny ta s c bn bin ng. Trong bn hin trng hai thi

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im c thnh lp da trn kt qu tch hp gia gii on nh t ng, gii on nh bng mt v iu tra thc a.

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CHNG 3 - XY DNG H THNG QUN L TI NGUYN RNG

3.1. Pht biu bi ton

Bi ton: Xy dng h thng thng tin qun ti nguyn rng

Yu cu: Xc nh c din tch bin ng rng ti a im no , lp cc bo co bin ng din tch, cng c tra cu, qun l d liu trn nn web, d liu v vin thm c x l t ng v cp nht v c s d liu.

3.2. C s phn chia rng v qun l rng

3.2.1. Khi nim v rng

Theo lut bo v v pht trin rng nm 2004, rng l mt h sinh thi bao gm qun th thc vt rng, ng vt rng, vi sinh vt rng, t rng v cc yu t mi trng khc. Rng gm rng trng v rng t nhin trn t rng sn xut, t rng phng h, t rng c dng.

3.2.2. Phn chia ranh gii i tng iu tra

i tng iu tra rng c phn chia theo n v hnh chnh n x. Mi x li c chia ra cc tiu khu; Mi tiu khu li chia lm nhiu khonh; Mi khonh li chia thnh cc phn khonh; Mi khonh hoc phn khonh li chia thnh cc l. Cc n v tiu khu, khonh, phn khonh c chia da vo cc c im t nhin d nhn bit nh sng sui, dng ni, ranh gii hnh chnh [6].

Din tch tiu khu vo khong 1000 ha; Khonh l n v thng k ti nguyn rng. Vic phn chia khonh ch thc hin cho t c rng v t trng i ni trc vi din tch trung bnh mi khonh l 100 ha; Phn khonh l mt phn din tch khonh c chia nh ra tin cho vic xc nh v tr v t chc sn xut trong tng khonh. Din tch trung bnh ca mi phn khonh l 10 ha; L l n v nh nht c chia ra trong tng phn khonh iu tra, thng k rng. Din tch nh nht tch l t c rng l 1ha.

3.2.3. Phn chia kiu trng thi rng

i vi cc kiu rng g l rng thng xanh v na rng l cn p dng h thng phn chia theo bn nhm trng thi I, II, III, IV. Trong cc nhm c cc kiu, trong cc kiu c cc kiu ph. Trong nhm I l t

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cha c rng; nhm II l rng phc hi; nhm III l rng th sinh v b tc ng; nhm IV l rng nguyn sinh, rng n nh. Cc nhm kiu trng thi rng c cc c trng sau:

Nhm I: Nhm khng c rng hoc hin ti cha thnh rng, ch c c, cy bi hoc cy g, tre mc ri rc. Ty theo hin trng, nhm ny c chia thnh: Kiu IA, c c trng bi lp thc b c, lau lch hoc chui rng; Kiu IB, c c trng bi lp thc b cy bi, cng c th c mt s cy g, tre mc ri rc; Kiu IC, c c trng bi cy thn g ti sinh vi s lng ng k so vi hai kiu IA, IB. Ch c xp vo kiu IC khi s lng cy g ti sinh c chiu cao trn l mt t t l.000 cy/ha tr ln.

Nhm II: Nhm rng phc hi cy tin phong c ng knh nh. Ty theo hin trng v ngun gc m chia ra Kiu IIA l rng phc hi sau nng ry, c trng bi lp cy tin phong a sng mc nhanh u tui, mt tng; Kiu IIB l rng phc hi sau khai thc kit, phn ln kiu ny bao gm nhng qun th non vi nhng loi cy tng i a sng, thnh phn loi phc tp khng u tui, u th khng r rng. Vt ln khi tn rng kiu ny c th cn st li mt s cy ca qun th c nhng tr lng khng ng k. Ch c xp vo kiu ny nhng qun th m ng knh ph bin khng vt qu 20cm.

Nhm III: Nhm rng th sinh b tc ng. Cc qun th rng chu tc ng khai ph ca con ngi nhiu mc khc nhau lm cho kt cu n nh ca rng t nhiu c s thay i. Ty theo mc tc ng v kh nng cung cp sn phm m nhm ny c chia lm 2 kiu:

+ Kiu IIIA c c trng bi nhng qun th b khai thc nhiu, kh nng khai thc hin ti b hn ch. Cu trc n nh ca rng b ph v hon ton hoc thay i v c bn. Kiu ny c chia lm kiu ph:

+ Kiu ph IIIA1 l rng b khai thc kit qu, tn rng b ph v tng mng ln. Tng trn c th cn st li mt s cy cao, to nhng phm cht xu, nhiu dy leo bi rm, tre na xm ln. Ty theo tnh hnh ti sinh m chia kiu ph IIIA1 ra thnh IIIAl.l thiu ti sinh; v IIIAl.2 ti sinh.

+ Kiu ph IIIA2 l rng b khai thc qu mc nhng c thi gian phc hi tt. c trng cho kiu ny l hnh thnh tng gia vn ln chim u th sinh thi vi lp cy i b phn c ng knh 20 - 30 cm.

44

Rng c 2 tng tr ln, tng trn tn khng lin tc c hnh thnh ch yu t nhng cy ca tng gia trc y, ri rc cn c mt s cy to khe vt tn ca tng rng c li. Ty theo thnh phn cy mc ch ca tng gia v tnh hnh ti sinh m chia ra IIIA2.l thiu ti sinh v IIIA2.2 ti sinh.

+ Kiu ph IIIA3 l rng b khai thc va phi hoc pht trin t IIIA2 ln. Qun th tng i khp kn vi 2 hoc nhiu tng. c trng ca kiu ny khc vi IIIA2 ch s lng cy nhiu hn v c mt s cy c ng knh ln (trn 35cm) c th khai thc s dng g ln. Kiu IIIB c c trng bi nhng qun th b cht chn ly ra mt t g qu, g tt nhng cha lm thay i ng k v kt cu n nh ca rng, kh nng cung cp ca rng cn nhiu, rng giu v tr lng vi thnh phn g ln cao.

Nhm IV l rng nguyn sinh hoc th sinh thnh thc cho n nay cha c khai thc s dng. Rng c cu trc n nh, nhiu tng, nhiu cp knh nhng i khi thiu tng gia v tng di. Nhm ny c hai kiu: kiu IVA l rng nguyn sinh; v kiu IVB, rng th sinh phc hi. Khi p dng bng phn loi ny vo tng vng phi cn c vo c trng ca cc trng thi m xc nh cc ch tiu nh lng v tit din ngang hay tr lng, tn che, ...

Phn chia trng thi rng tre na

a) Phn chia rng tre na thun loi

o Tre na tp (D 2cm), k hiu tn loi u th l N1 (Na); V1 (Vu); L1(L ); Le1 (le),

o Tre na to (D 2cm), K hiu tn loi u th l N2 (Na); V2 (Vu); L2(L ); Le2 (Le).

b) Phn chia rng tre na hn giao vi g theo 2 loi:

o Tre na xen g (na l ch yu). Tng tre na c chia theo tiu chun chia ca rng tre na, tng cy g nguyn. K hiu trng thi l Na + tn loi cy g u th. V d: N.IIIa + Re

o Rng g xen Tre na. Tng cy g chia theo tiu chun rng g, tng na nguyn. K hiu trng thi l: g + na. V d: IIIA3 + N

Phn chia trng thi rng trng

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a) Cn c phn chia trng thi

Trng thi rng trng c phn chia da trn loi cy trng; cp tui, hoc nm trng.

Mi mt loi cy chia ring mt trng thi. Trng hp hn giao nhiu loi cy th mi mt phng thc hn giao chia ring mt trng thi.

Cp tui c chia lm 5 cp sau: Cp I t 1 - 5 tui; Cp II t 6 10 tui; Cp III t 11 - 15 tui; Cp IV t 16 - 20 tui; Cp V t trn 20 tui.

b) K hiu trng thi

Trng thi rng trng c k hiu l Tn cy v cp tui (hoc nm trng). V d: trng thi rng trng Thng cp tui II c k hiu l Th.II; hoc Keo trng nm 2004, k hiu l K.04.

Ngun: Qui phm thit k kinh doanh rng QPN6-84, do B Lm nghip c, nay l b NN&PTNT ban hnh nm 1984.

3.3. Kho st bi ton

Hin nay vic gii on nh vin thm v xy dng c s d liu khng gian Vit Nam theo qui trnh s dng cc phn mm x l nh vin thm nh ENVI, ERDAS imagine, gii on phn loi i tng sau chuyn kt qu sang phn mm GIS nh ArcGIS, Mapinfo, xy dng bn hin trng a s d liu c lu tr di tp d liu ca cc phn mm GIS nh *.shp ca ArcGIS hoc *.tab ca Mapinfo vic s dng cc h qun tr mnh lu tr d liu nh Oracle hoc s dng thnh phn ArcSDE kt hp vi mt h qun tr d liu quan h nh MS SQL Server, MySQL, DB2 cn hn ch v l do cng ngh v chi ph bn quyn ca cc thnh phn phn mm dn n vic chia s d liu GIS cn kh khn, mt khc vic gii on v xy dng c s d liu lm th cng thng da vo gii on bng mt do vy xy dng h thng thng tin h tr theo di din bin ti nguyn cn nhiu bt cp.

gii quyt bi ton xy dng h thng qun l ti nguyn ti s dng cc cng c m ngun m vi u im c cng ng pht trin, c th lp trnh x l t ng v h tr nhiu nh dng d liu khc nhau do h thng s dng gii php m ngun m c th s dng d liu ca cc h

46

thng khc v xut d liu cho cc h thng khc s dng m khng gp tr ngi g.

3.4. Cc cng c h tr m ngun m

3.4.1. Cng c x l nh vin thm Grass

GRASS l mt trong nhng ng dng ngun m rt mnh v phn tch d liu raster. GRASS c kh nng gii on nh v tinh kh tt so cc phn mm thng mi gii on nh v tinh ring rt t tin nh ENVI hay ERDAS.

Hnh 2. Phn mm GRASS

Lch s pht trin cc phin bn ca Grass:

o Nm 1985: bn GRASS 1.0, GRASSnet c thnh lp o Nm 1986: bn GRASS 1.1; on gii thng Cc h thng

mu ca Gii thng Quc gia t URISA o Nm 1987: bn GRASS 2.0; ln u tin pht hnh

GRASSClippings, do William Shatner c (vai Captain Kirk trong phim Star Trek)

o Nm 1988: bn GRASS 3.0; on gii thng Thnh tu Nghin cu v Pht trin ca Qun i (bn tc gi l Webster, Goran, Shapiro v Westervelt)

47

o Nm 1991: bn GRASS 4.0; c pht hnh trn internet s ni ting ca GRASS tng ln cng vi cc Trng i hc, cc t chc kinh doanh cng nh cc c quan nh nc

o Nm 2002: bn GRASS 5.0.0 n nh c pht hnh (do Nhm pht trin GRASS, ng u l Markus Neteler ti ITC-irst, Trento, )

o Nm 2005: pht hnh bn GRASS 6.0.0 cho n nay cc phin bn n nh vn l 6.x.x

GRASS c t chc theo kiu module. Mi khi cn thc hin mt iu g th thc thi module lin quan. iu ny gip tit kim ti nguyn h thng. K t phin bn 6.0.0, GRASS c cuc cch mng v giao din ngi dng ha (GUI) vi trnh qun l GIS (GIS Manager), gip cho vic s dng GRASS d dng hn. Hu ht cc module quan trng v thng s dng trong s khong 400 module lnh ca GRASS c a vo GUI.

GRASS c vit bng C, c th hot ng trn nhiu h iu hnh nh Linux, Unix, FreeBSD v MS-Windows.

Cc nh dng d liu h tr gm:

o Raster: ASCII, ARC/GRID, E00, GIF, GMT, TIF, PNG, ERDAS LAN, Vis5D, SURFER (.grd) ...

o Images: CEOS (SAR, SRTM, LANDSAT7 etc.), ERDAS LAN, HDF, LANDSAT TM/MSS, NHAP aerial photos, SAR, SPOT

o Vector: ASCII, ARC/INFO ungenerate, ARC/INFO E00, ArcView SHAPE (with topology correction), BIL, DLG (U.S.), DXF,

DXF3D, GMT, GPS-ASCII, USGS-DEM, IDRISI, MOSS,

MapInfo MIF, TIGER, VRML, ...

o H tr kt ni n cc h c s d liu (PostgreSQL, mySQL,

SQLite, ODBC, ...)

Cc module lnh ca GRASS bao gm cc nhm sau:

o Cc module v trnh by bt u bng ch d. (display) o Cc module v CSDL bt u bng ch db. (database) o Cc module tng qut bt u bng ch g. (general)

48

o Cc module lin quan n nh vin thm bt u bng ch i. o Cc module lin quan n lnh v bt u bng ch p. (paint) o Cc module lin quan n nh chp bt u bng ch photo. o Cc module lin quan n Postscript bt u bng ch ps. o Cc module v d liu raster bt u bng ch r. (raster) o Cc module v d liu raster 3D bt u bng ch r3. o Cc module v d liu vector bt u bng ch v. (vector) o Cc module lin quan n CSDL PostgresSQL bt u bng ch

pg. (postgreSQL).

M ngun v gi ci t bin dch ca GRASS c cung cp ti a ch http://grass.osgeo.org/index.php. Vic ci t GRASS ty thuc vo h iu hnh m c nhng cch ci t khc nhau.

So snh GRASS 6.0 vi ArcGIS 9.0 v ENVI:

ArcGIS l b cng c phn mm x l, qun l d liu, phn tch v

bo co GIS mnh ca hng phn mm ESRI, c s dng nhiu nc trn

th gii v Vit Nam. ArcGIS c y cc gii php GIS cho cc n v,

t chc t ArcGIS Desktop, ArcGIS Server, ArcGIS IMS, ArcCatalog Hin

ti Vit Nam ArcGIS c s dng kh ph bin trong cc d n, chng

trnh quc gia ca B Ti nguyn Mi trng, B Nng nghip v Pht trin

nng thn. Tuy nhin, ArcGIS l b phn mm gip qun l, phn tch d

liu GIS, cn mun gii on nh v tnh th cn s dng thm phn mm x

l gii on nh v tinh nh ENVI hoc ERDAS imagine. y l nhng phn

mm v vin thm v qun l d liu GIS thng mi c gi thnh kh cao.

Di y l so snh gia s dng phn mm GRASS m ngun m vi gii

php s dng cc phn mm thng mi ArcGIS v ENVI gii on nh

v tinh thnh lp bn hin trng ti nguyn rng v phn tch bin ng

din tch rng.

49

Gi phn mm Chc nng phn mm Gi

ArcGIS9.0(ArcView) Cng c GIS xy dng v

cng c phn tch bn s

$1,500

ArcGIS9.0(ArcEditor) Cng c bin tp v qun l d

liu GIS

$7,000

ArcGIS 9.0 (ArcInfo) Cng c ny bao gm tt c

cc chc nng ca ArcView v

ArcEditor v kh nng chuyn

i d liu

$14,000

ArcGIS 3D Analyst

Extension

Cng c xy dng m hnh

bn s 3D

$2,500

ArcGIS Spatial

Analyst Extension

Cng c phn tch d liu dng

Raster

$2,500

ArcGIS

Interoperability

Extension

Thnh phn cho php s dng

trc tip cc dng d liu khc

m khng cn chuyn nh

dng trc

$2,500

ENVI Phn mm x l nh vin thm $4,500

GRASS 6.0 Gii php GIS m ngun m Min ph

Bng 11. So snh chi ph bn quyn phn mm (cho mt giy php s dng) Theo http://www.covenant-tech.com/thesis.pdf

ArcGIS 9.3 GRASS 6.0

Windows 2003, XP, Vista hoc

Windows 7

Windows 98 tr ln, Linux hoc

Mac OS

50

RAM ti thiu 1GB RAM ti thiu 128 MB

CPU ti thiu 1.6 GHz Khng c khuyn co

Bng 12. So snh v yu cu phn cng h thng. Theo http://wikis.esri.com/wiki/display/ag93bsr/ArcGIS+Desktop v

http://grass.osgeo.org/wiki/Installation_Guide

Cc phng php phn loi trong GRASS

GRASS c y cc modun thc hin cc phng php phn loi nh nh: phn loi khng kim nh, phn loi c kim nh. Bng di lit k cc phng php phn loi v cc modun ca GRASS thc hin:

Phn loi

khng kim

nh

Phn loi c

kim nh 1

Phn loi c

kim nh 2

Phn loi hnh

hc c kim

nh

X l nh S dng modun r.seg thc hin vic lm mn d liu v phn on

nh da trn m hnh Mumford-Shah. Bc ny l bc tin x l

nh cho cc bc phn loi tip theo, kt qu ca bc ny l nh

c lm mn v phn on

Tin x l S dng

modun i.cluster

phn cm nh

da trn gi tr

ph

S dng

modun i.class

phn lp

nh theo thit

lp ca ngi

dng

S dng

modun

i.gensig

phn lp nh

da vo vng

d liu mu,

S dng modun

i.gensigset

phn lp nh

da vo vng

d liu mu

Phn loi S dng

modun

i.maxlik phn

loi nh da

vo kha phn

S dng

modun

i.maxlik phn

loi nh da

vo kha

S dng

modun

i.maxlik phn

loi nh da

vo kha phn

S dng modun

i.smap phn loi

nh da vo

kha phn tch

51

tch ph

i.cluster

phn tch ph

i.class

tch ph

i.gensig

ph i.gensigset

Bng 13. Cc phng php phn loi nh bng GRASS

3.4.2. H qun tr c s d liu khng gian PostgreSQL v PostGIS

PostgreSQL l h c s d liu quan h ngun m. PostGIS l phn m rng ca PostgreSQL, cho php lu tr d liu v thc hin cc phn tch lin quan n GIS trong PostgreSQL. ci t trc tin chng ta phi ci t h qun tr c s d liu Postgre phin bn hin ti n nh l 8.4 c ti http://www.postgresql.org/. Sau ci t phn m rng Postgis phin bn hin ti n nh l 1.5 c ti http://postgis.org/.

PostGIS to thm bng Spatial_ref_sys lu thng tin h quy chiu v bng geometry_columns lu kiu i tng khng gian.

thao tc vi c s d liu c th dng theo cc cch l s dng cng c pgAdminIII ca Postgre hoc s dng trc tip cu lnh trong Command prompt hoc cc cng c khc nh Postgis manager tch hp vi Quantum GIS.

Hnh 3. Cng c qun tr pgAdmin III

52

3.4.3. WebGIS v MapServer

WebGIS c xem nh l mt h thng thng tin a l c phn b qua mi trng mng my tnh tch hp, phn phi v truyn ti thng tin a l trc din trn WWW thng qua Internet.

MapServer l phn mm m ngun m cho php to cc bn ng v trnh by d liu khng gian trn Web.

MapServer c cc c im sau:

H tr cc dch v WebGIS theo chun OGC, bao gm: WMS Server, WMS Client, WFS Server, WFS Client v WCS Server.

Xut bn bn vi nhiu u im: o V i tng theo t l; o Hin th nhn theo i tng v gii quyt trng lp nhn; o Ty bin giao din, mu trc khi xut; o S dng font: TrueFont; o C cc thnh phn ca bn nh thc t l, ch gii, bn

tham chiu, mi tn hng bc; o To bn chuyn da trn biu thc truy vn trn cc

lp c s; H tr cc ngn ng kch bn ph bin v mi trng pht trin

nh .NET, PHP, Perl, Python, Java, v Ruby. H tr cc h iu hnh: Linux, Windows, MAC OS X, Solaris. H tr nh dng d liu raster v vector:

o TIFF/GeoTIFF, GIF, PNG, ERDAS, JPEG v EPPL7. o ESRI shapefile, PostGIS, ESRI ArcSDE, Oracle Spatial,

MySQL, o H tr li chiu: vi hn 1000 li chiu khc nhau.

53

HnHnh 4. M hnh hot ng ca Mapserver

MapServer c th hot ng 2 ch CGI (Common Gateway Interface) v API (Application Program Interface). ch CGI, cc chc nng ca MapServer trong mi trng WebServer l CGI MapScript. y l cch thc d dng khi to v pht trin mt ng dng. ch API, c th truy cp MapServer bng ASP, PHP, Perl hoc Python; ch ny cho php xy dng cc ng dng uyn chuyn, giu cc chc nng v c kh nng truy cp cc c s d liu m rng khc.

Hnh 5. ng dng WebGIS

54

MapServer hot ng da vo cc mu l chnh. Trc khi thc thi yu cu ca web, MapServer c tp tin cu hnh (mapfile) m t cc lp v cc thnh phn khc ca bn . N s v v lu li bn . Tip theo, n s c mt hoc nhiu tp tin mu HTML m n nhn din trong tp tin cu hnh. Mi tp tin mu s cha ng cc tags HTML v cc chui MapServer c bit. Cc chui ny s c s dng, v d chui ch ng dn lu nh bn do MapServer to ra, hoc chui dng nhn din cc lp no s c sp xp, MapServer thay th cc gi tr hin ti vo cc cc chui ny v gi lung d liu v cho WebServer WebServer tip tc chuyn v cho trnh duyt. Khi c mt yu cu mi pht sinh, MapServer s nhn yu cu t WebServer vi cc gi tr mi v chu trnh c th tip din.

3.5. M hnh h thng thng tin qun l ti nguyn rng

3.5.1. M hnh tng quan

Hnh 6. M hnh tng quan h thng

ti xy dng h thng theo m hnh Clien/Server trn nn ng dng web. Pha client s dng cc trnh duyt web khai thc d liu v hin th bn qua mng Internet m khng yu cu ci t phn mm GIS chuyn dng.

Pha server bao gm cc thnh phn:

55

- DB Server: H qun tr c s d liu quan h hoc i tng lu tr d liu ca h thng bao gm cc d liu dng thuc tnh ca h thng. ti s dng h qun tr Postgre.

- GIS Server l thnh phn c s d liu khng gian cho php lu tr d liu khng gian trong cc h qun tr c s d liu. ti s dng cng c PostGIS mt thnh phn m rng tch hp vi Postgre lu tr d liu khng gian.

- GRASS DB l d liu khng gian c lu tr di dng c s d liu ca phn mm GRASS. Dng lu tr d liu trong qu trnh x l nh v tinh dng raster.

- WEB Server l thnh phn cung cp ni dung di dng HTML. ti s dng Apache xy dng Web Server.

- DB Interface l thnh phn tr v cc nh bn t c s d liu khng gian.

Thnh phn Input Instruction l cc script file ca Grass x l d liu t ng sau cp nht d liu vo Grass DB v sau bc x l cui cng d liu c lu tr trong h qun tr d liu DB Server.

3.5.2. Phng php xy dng c s d liu qun l ti nguyn rng

xy dng c s d liu qun l ti nguyn rng v nh gi bin ng ti nguyn rng ti s dng phng php kt hp x l nh t ng v GIS. Bc u tin xy dng c s d liu hin trng rng t bn hin trng rng nm 2005 ca Vit Nam do Vin iu tra quy hoch rng xy dng trn Mapinfo. Kt qu ca bc ny l chuyn i d liu t nh dng ca Mapinfo sang lu tr trong h qun tr d liu PostgreSQL v thnh phn m rng PostGIS tn dng kh nng qun tr v chia s d liu ca h qun tr c s d liu lm chun lu tr d liu khng gian cho cc cng c m ngun m s dng trong h thng. Sau d liu s c cp nht b sung thng xuyn t cc ngun nh v tinh trong bc u d liu c cp nht b xung thng qua d liu nh v tinh Landsat-7 hoc SPOT5 hoc MODIS vi mi loi d liu nh v tinh th cn c cc kha gii on phn loi i tng bng GRASS, sau d liu phn loi c xy dng lp bn hin trng ti nguyn rng. Di y l quy trnh b sung d liu vo c s d liu t nh v tinh.

56

Hnh 7. Quy trnh cp nht d liu ti nguyn rng

Bc 1: Cc d liu nh ca vng nghin cu c ly v, trong phm vi th nghim ti s dng nh v tinh Landsat-7. Trong thc t ty vo tng i tng nghin cu c th s dng cc loi nh khc nhau nh nu cn nghin cu i tng vi chnh xc cao c th s dng nh phn gii cao nh SPOT5, Quickbird hoc nu cn nghin cu bin ng nhanh chnh xc va phi th c th s dng nh c chu k ngn nh Modis.

Bc 2: L qu trnh hiu chnh nh v tinh nh hiu chnh ph, nn nh, bin i nh, t hp mu tng cng cht lng nh, ct vng nghin cu t nh gc.

Bc 3: S dng cc phng php phn loi phn loi i tng i vi mi loi nh v i tng nghin cu s c kha phn loi khc nhau. ti s dng cc kha phn loi t kt qu nghin cu c ca Trng i hc Lm nghip trong vic xy dng bn rng t nh v tinh. T kt qu phn loi xy dng lp bn hin trng mi ca i tng nghin cu cp nht vo c s d liu v xy dng bn bin ng ca i tng.

57

Bc 5: T c s d liu GIS ca h thng ly ra bn hin trng c ca i tng ti cc thi im c trc xy dng bn bin ng ca i tng.

Bc 4, 6: Thc hin tnh ton bin ng gia 2 lp bn ca i tng cc thi im khc nhau thnh lp bn bin ng ca i tng.

Bc 7: D liu v lp bn hin trng mi ca i tng c cp nht vo c s d liu.

3.6. Th nghim v kt qu

3.6.1. Gii on d liu nh v tinh

D liu th nghim l nh Landsat ca M, c phn gii trung bnh 30m x 30m trong di sng nhn thy v cn hng ngoi, nh c cp nht hng thng ph hp vi lnh vc nghin cu ca ti. Mt khc, t thng 1 nm 2009, Chng trnh nh hng khng quc gia ca Hoa K (National Aerial Photography Program - NAPP) cho php download min ph nh Landsat mi nht trn ton th gii t Website: http://glovis.usgs.gov/, nh c cp nht theo tng thng.

Thng s k thut ca nh Landsat ETM+ nh sau:

phn gii (Spatial Resolution): 30 m (60 m - thermal, 15m pan) Bc sng (Spectral Range): 0.45 - 12.5 m S lng knh ph (Number of Bands): 8 Chu k bay chp (Temporal Resolution): 16 days Kch thc nh (Image Size): 185 km x 185 km

Thng s k thut ca nh Landsat TM nh sau:

phn gii (Spatial Resolution): 30 m (120 m - thermal) Bc sng (Spectral Range): 0.45 - 12.5 m S lng knh ph (Number of Bands): 7 Chu k bay chp (Temporal Resolution): 16 days Kch thc nh (Image Size): 185 km x 185 km

ly d liu th nghim theo di bin ng rng, ti la chn khu vc ti huyn Kim Bi, tnh Ha Bnh. nh la chn l nh Landsat TM v ETM+, tiu chun nh c s dng l cc bc nh c che ph ca my nh hn 3%.

58

Hnh 8. nh Landsat TM khu vc nghin cu nm 2007

Hnh 9. nh huyn Kim Bi - Ha Bnh sau khi ct

59

phn loi t ng ti s dng b kha phn loi theo cc kt qu nghin cu ca Vin sinh thi rng v mi trng i hc Lm nghip, b kha phn loi da vo ch s NDVI c tnh theo cng thc sau:

( ))( REDNIR

REDNIRNDVI +=

Trong : NIR l gi tr im nh trn knh cn hng ngoi

RED l gi tr im nh trn knh

Knh NIR l band 4 v knh RED l band 3 trn nh Landsat.

Ngng NDVI i tng N X S X1 X2

CD CT Gp

MN 23 -0.382 0.370 -0.536 -0.228 -1.000 -0.168 MN

NN 239 -0.065 0.335 -0.108 -0.021

DK 86 -0.005 0.254 -0.060 0.050-0.168 0.032 DK

Bd 126 0.059 0.107 0.040 0.078

K 163 0.077 0.157 0.052 0.102

BdK 56 0.060 0.171 0.014 0.106

0.032 0.105 RT

Ib 271 0.144 0.233 0.115 0.172

Ic 389 0.150 0.237 0.126 0.174

TN 46 0.152 0.163 0.104 0.200

Ia 616 0.132 0.205 0.116 0.149

C 544 0.144 0.346 0.114 0.174

0.105 0.196 CCR

Nra 73 0.244 0.223 0.192 0.296 0.196 0.299 Nra

IIa,Iib 144 0.344 0.252 0.302 0.386 0.299 0.469 RPH

IIIa1,2 129 0.609 0.323 0.552 0.666 0.469 1.000 RBTD

Bng 14. Kha phn loi rng nh Landsat

Trong

60

- N: Dung lng mu

- X: Gi tr NDVI trung bnh

- S: Sai s tiu chun;

NSXX 21 =

NSXX 22 +=

- X1, X2 l gi tr NDVI cn di v cn trn ca tng i tng

- CD, CT l gi tr NDVI cn di, cn trn ca nhm i tng, v cng thc tnh nh sau:

2)1max(2)min(1

)min(1+= iiii

XXXCD

2)max(2)1min(1

)max(2ii

ii

XXXCT

+= + Vi i l nhm i tng th i.

Cc bc thc hin phn loi nh bng GRASS nh sau:

Bc 1: Thc hin nhp nh vo GRASS bng modun r.in.gdal

Bc 2: Bc tin x l nh hiu chnh hnh hc bng cc modun i.points, i.vpoints; loi b nh hng kh quyn bng modun i.atcorr, i.landsat.dehaze; loi b nh hng a hnh bng modun i.topo.corr; loi b my bng modun i.landsat.acca.

Bc 3: Thc hin ct vng nh nghin cu bng vic thit lp mt n l lp ranh gii ca vng nghin cu s dng modun r.mask v modun r.mapcalc hoc ta c th ct nh bng vic thit lp vng lm vic l lp ranh gii ca vng nghin cu bng r.region sau dng r.mapcalc sao chp vng cn ct thnh lp mi theo gii hn vng thit lp.

Bc 4: Thc hin to nh ch s thc vt NDVI bng modun r.mapcalc theo cng thc "ndvi=1.0*(nir-red)/(nir+red)", kt qu thu c nh NDVI.

61

Hnh 10. nh ch s NDVI nm 2007

Bc 5: Xy dng file kha phn loi dng text c ni dung [20]

-1.000 thru -0.168= 1 MN

-0.168 thru 0.032=2 DK

0.033 thru 0.105= 3 Rung trong

0.106 thru 0.196=4 CCR

0.197 thru 0.299=5 Nra

0.300 thru 0.469=6 RPH

0.470 thru 1.000=7 RBTD

Bc 6: Thc hin phn loi bng i.class v i.maxlik

62

Kt qu phn loi theo kha vi nh nm 2007

Tng s pixel: 771311

STT i tng Tng s pixel Din tch (ha) %

1 MN 135034 12153.06 17.507

2 NN 154241 13881.69 19.997

3 RT 50637 4557.33 6.565

4 CCR 93270 8394.3 12.092

5 Nra 73487 6613.83 9.528

6 RPH 131809 11862.81 17.089

7 RBTD 130788 11770.92 16.957

Bng 15. Kt qu phn loi nh theo ch s NDVI

Hnh 11. nh phn loi i tng nm 2007

63

3.6.2. Xy dng c s d liu qun l ti nguyn rng

Trong phm vi th nghim ti c s d liu qun l ti nguyn rng gm cc lp thng tin: lp thng tin hnh chnh v lp thng tin rng.

Lp thng tin hnh chnh c ly t bn hnh chnh ca huyn Kim bi Ha Bnh dng TAB ca Mapinfo sau chuyn i d liu lu tr trong c s d liu PostgreSQL v thnh phn m rng PostGIS.

Lp thng tin rng c xy dng t kt qu phn loi nh v tinh bc trn kt hp vi bn ti nguyn rng nm 2005 ca Vin iu tra qui hoch rng. Sau khi c cc lp bn rng tng thi im khc nhau tin hnh chng lp nh gi bin ng, xy dng bo co bin ng ti nguyn rng. Cu trc ca bng d liu qun l thng tin rng nh sau:

TT Tn trng Kiu d liu Kch thc Null Gii thch

1 Gid int4 4 N Kha chnh

2 TYPE int4 4 Y Kiu i tng

3 TYPE_NAME varchar (39) -1 Y Tn i tng

4 DTICH float8 8 Y Din tch

5 XA varchar (17) -1 Y Tn X

6 HUYEN varchar (11) -1 Y Tn Huyn

7 TINH varchar (14) -1 Y Tn Tnh

8 the_geom geometry -1 Y Thuc tnh khng gian

Bng 16. Cu trc bng d liu lp rng

Vi mi d liu nh v tinh mt thi im thu nhn xy dng nh phn loi v bn ti nguyn rng ti thi im . Mi lp bn rng c lu theo mt bng d liu ring.

3.6.3. Xy dng modun website hin th bn v biu bin ng

hin th d liu, ti xy dng modun website hin th bn bng cng c Mapserver. Cc bc thc hin nh sau:

64

Bc 1: Xy dng webserver bng Apache

Bc 2: Ci t thnh phn mapserver v h qun tr c s d liu PostgreSQL cng vi thnh phn m rng PostGIS theo m hnh trin khai nh sau

Hnh 12. M hnh trin khai website qun l ti nguyn rng

Bc 3: Xy dng file cu hnh mapserver l mapfile c phn m rng l

(*.map) c nhim v quy nh vic ngun d liu cho mapserver v cch thc

hin th thng tin, mu sc i tng, Ni dung ca mapfile cho hin th lp

d liu bn Kim Bi nh sau:

MAP NAME THEO_DOI_TAI_NGUYEN_RUNG STATUS ON SIZE 800 600 SYMBOLSET ../etc/symbols.txt EXTENT 434131 2270139 469457 2303365 UNITS METERS SHAPEPATH "../data" IMAGECOLOR 255 255 255 FONTSET ../etc/fonts.txt # Start of web interface definition WEB

MINSCALE 2000000 MAXSCALE 50000000

IMAGEPATH "C:\OSGeo4W/tmp/ms_tmp/" IMAGEURL "/ms_tmp/"

END

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REFERENCE IMAGE images/keymap.png EXTENT 434131 2270139 469457 2303365 STATUS ON

COLOR -1 -1 -1 OUTLINECOLOR 255 0 0 SIZE 120 90

END LEGEND

KEYSIZE 18 12 LABEL TYPE BITMAP SIZE MEDIUM COLOR 0 0 89 END STATUS ON

END SCALEBAR

IMAGECOLOR 255 255 255 LABEL COLOR 0 0 0 SIZE SMALL END SIZE 150 5 COLOR 255 255 255 UNITS kilometers INTERVALS 5 STATUS ON

END QUERYMAP

STYLE HILITE COLOR 255 0 0

END LAYER

CONNECTIONTYPE postgis CONNECTION "host=localhost dbname=kimboi user=postgres password=admin port=5432"

DATA "the_geom FROM rung07" NAME "rung2007"

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TYPE POLYGON STATUS ON CLASSITEM 'TYPE_NAME' CLASS

NAME "TYPE_NAME = Cy cng nghip" EXPRESSION "Cy cng nghip" STYLE OUTLINECOLOR 0 0 0 COLOR 157 186 12 END

END CLASS NAME "TYPE_NAME = Cy nng nghip" EXPRESSION "Cy nng nghip" STYLE OUTLINECOLOR 0 0 0 COLOR 171 250 81 END END CLASS NAME "TYPE_NAME = Dn c" EXPRESSION "Dn c" STYLE OUTLINECOLOR 0 0 0 COLOR 146 78 45 END END CLASS NAME "TYPE_NAME = Mt nc" EXPRESSION "Mt nc" STYLE OUTLINECOLOR 0 0 0 COLOR 255 255 255 END END CLASS NAME "TYPE_NAME = Ni " EXPRESSION "Ni " STYLE

67

OUTLINECOLOR 0 0 0 COLOR 255 255 127 END END CLASS NAME "TYPE_NAME = Nng ry" EXPRESSION "Nng ry" STYLE OUTLINECOLOR 0 0 0 COLOR 0 0 255 END END CLASS NAME "TYPE_NAME = Rng ngho" EXPRESSION "Rng ngho" STYLE OUTLINECOLOR 0 0 0 COLOR 0 85 0 END END CLASS NAME "TYPE_NAME = Rng phc hi" EXPRESSION "Rng phc hi" STYLE OUTLINECOLOR 0 0 0 COLOR 85 255 127 END END CLASS NAME "TYPE_NAME = Rng trung bnh" EXPRESSION "Rng trung bnh" STYLE OUTLINECOLOR 0 0 0 COLOR 0 170 0 END END CLASS NAME "TYPE_NAME = Rng trng" EXPRESSION "Rng trng"

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STYLE OUTLINECOLOR 0 0 0 COLOR 0 170 0 END END CLASS NAME "TYPE_NAME = t trng" EXPRESSION "t trng" STYLE OUTLINECOLOR 0 0 0 COLOR 222 209 107 END END END END

END # Map File Bc 4: Xy dng hin th d liu bn bng ngn ng PHP da trn

phn m ngun m Ka-Map. Kt qu thc hin nh sau:

Hnh 13. M hnh pht trin website bng mapserver

69

Hnh 14. Giao din website theo di ti nguyn rng

70

Bc 5: Xy dng biu bo co bin ng din tch rng. Kt qu thc hin nh sau:

Hnh 15. Kt qu bin ng bng biu

71

to v biu , ti s dng th vin FusionCharts v ngn ng lp trnh PHP. Mt s on m ngun v biu .

File bieudo_biendong.php

dien dong dien tich

72

$strCatChartDataURL = encodeDataURL("Data_Rung.php",true);

echo renderChart("FusionCharts/MSColumn3D.swf", $strCatChartDataURL ,"","Biendongnam", 875, 350, false, true);

?>

File bieudo_biendong.php

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header('Content-type: text/xml');

echo $strXML;

function getDataRung789XML($forDataURL) {

$connect = "host=localhost dbname=kimboi user=postgres password=admin port=5432";

$conn=pg_connect($connect);

$catXMLDone = false;

$strCat = "";

$strCat .= "";

$strCat .= "";

$strCat .= "";

$sql ="Select \"TYPE_NAME\" from Rung07 group by \"TYPE_NAME\"";

$result = pg_query($conn, $sql);

$strDataXML = "";

if ($result) {

while ($row = pg_fetch_row($result)) {

$strDataXML.= "";

$sql ="SELECT rung07.\"TYPE_NAME\" as tt07, sum(rung07.\"DTICH\") as dt07, rung08.\"TYPE_NAME\" as tt08, sum(rung08.\"DTICH\") as dt08, rung09.\"TYPE_NAME\" as tt09, sum(rung09.\"DTICH\") as dt09 FROM public.rung07, public.rung08, public.rung09 WHERE

74

public.rung07.\"ID\"=public.rung08.\"ID\" AND public.rung08.\"TYPE_NAME\"='". $row[0] ."' AND public.rung07.\"ID\"=public.rung09.\"ID\" GROUP BY rung07.\"TYPE_NAME\", rung08.\"TYPE_NAME\", rung09.\"TYPE_NAME\"";

$result2 = pg_query($conn, $sql);

while($ors = pg_fetch_row($result2)) {

$strLink = urlencode("javaScript:updateProductChart(2007 " . $ors['dt07'] . ");");

$strLink = urlencode("javaScript:updateProductChart(2008 " . $ors['dt08'] . ");");

$strLink = urlencode("javaScript:updateProductChart(2009 " . $ors['dt09'] . ");");

$strDataXML .= "";

$strDataXML .= "";

$strDataXML .= "";

}

$catXMLDone = true;

mysql_free_result($result2);

$strDataXML .= "";

}

}

}

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$strCat .= "";

$strXML = $strCat . $strDataXML;

return $strXML;

}

?>

76

KT LUN

Qua kt qu nghin cu ti a ra mt s kt lun nh sau:

C th s dng nh v tinh xy dng c s d liu theo di gim st v ti nguyn rng, c th xc nh nhanh cc din tch rng b bin ng, c bit l vi nhng din tch nh m vi cc phng php truyn thng kh c th xc nh c da vo cc t liu nh v tinh ph hp. Phng php xy dng c s d liu v nh gi bin ng sau phn loi kt hp vi GIS c nhng u im nh: khng ph thuc vo d liu nh v tinh, khng cn phi chp nhng thi gian tng ng vi nhau. Ty vo yu cu nh gi bin ng c th th c th la chn d liu nh ph hp xc nh bin ng.

C th s dng cc gii php GIS m ngun m ng b xy dng mt h thng theo di, gim st ti nguyn t qu trnh x l nh v tinh, phn loi nh, xy dng t chc c s d liu khng gian v xy dng website qun l trc tuyn hoc webservice chia s thng tin GIS trc tuyn.

chnh xc ca cc nh phn loi rng ph thuc vo phng php phn loi, trong qu trnh th nghim ti s dng phng php phn loi c gim st v s dng kha phn loi da trn ch s NDVI. Theo cc nghin cu thc nghim th phng php ny c chnh xc t 80,1 n 91,9%. Ni dung nghin cu t c ca ti:

- Nghin cu cng c m ngun m GRASS ng dng cc modun x l, gii on nh v tinh.

- Nghin cu h qun tr d liu m ngun m Postgre v thnh phn m rng PostGIS lu tr d liu khng gian xy dng c s d liu ti nguyn rng.

- Nghin cu Mapserver lm cng c hin th chia s d liu GIS trn nn web.

- Th nghim p dng cc kt qu nghin cu xy dng c s d liu ti nguyn rng ti Kim Bi Ha Bnh.

Bn cnh nhng kt qu t c nh s dng cng ngh gii on nh vin thm t ng th trong ti cng cn tn ti mt s vn cn khc phc l: ti mi dng li vic s dng b kha phn loi da vo ch s

77

NDVI, y l cc ch s phn nh thc vt, cc ch s ny ch yu da vo s chnh lch gi tr gia knh cn hng ngoi v knh . Trong thc t nhiu i tng cc khc nhau v bn cht nhng vn c ch s thc vt ging nhau. Trong qu trnh xy dng c s d liu t ng nh vic gii on t ng th chnh xc hon ton ph thuc vo kha phn loi.

Hng nghin cu tip theo l hon thin phng php gii on t ng nh v tinh, c bit l nhng nh v tinh c phn gii cao xc nh din tch cc trng thi rng v bin ng ca chng. Khi c c s d liu th ng dng cc k thut datamining xy dng cc kch bn bin ng gip cho cc c quan qun l c cc thng tin theo di, d bo v din bin ti nguyn v a ra nhng bin php kp thi bo v ti nguyn rng.

78

TI LIU THAM KHO I. Ti liu Ting Vit

1.

V Tin Hinh, Phm Ngc Giao (1997), Gio trnh iu tra rng, NXB Nng nghip.

2.

Nguyn Ngc Thch (2005), C s vin thm, i hc Khoa hc T nhin, HQG H Ni.

3. Chu Th Bnh (2001), ng dng cng ngh tin hc khai thc nhng thng tin c bn trn t liu vin thm, nhm phc v vic nghin cu mt s c im rng Vit Nam, Lun n tin s, Trng H M i cht, H Ni.

4. Nguyn nh Dng v nnk (2000), Nghin cu bin ng rng t nhin ti khu vc Tnh Linh, tn