Hệ thống thông tin địa lí

1

LI CM N

Chng em xin chn thnh cm n Khoa Cng ngh Thng tin , trng i hc

Giao Thng vn ti TP. HCM to iu kin thun li cho chng em hc tp v

thc hin ti tt nghip ny.

Chng em xin by t lng bit n su sc ti thy ng Nhn Cch tn tnh

hng dn ch bo chng em trong qu trnh thc hin ti.

Chng em xin chn thnh cm n qu thy c trong khoa Cng ngh Thng tin

tn tnh ging dy , trang b cho em nhng kin thc qu bu trong nm va qua.

Chng con xin chn thnh cm n ng B, Cha M lun ng vin ng h

vt cht ln tinh thn trong sut thi gian qua.

Chng em xin cm n s quan tm gip v ng h ca cc anh ch bn b

trong qu trnh thc hin kha ti.

Mc d c gng hon thnh kha lun trong phm vi v kh nng cho php

nhng chc chn s ko trnh khi nhng thiu st. Chng em rt mong nhn c

s thng cm, gp v tn tnh ch bo ca qu thy c v cc bn.

TP. H Ch Minh, thng 01 nm 2010

Nhm sinh vin thc hin:

Nguyn Quc Phng - Nguyn Mnh Cng

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M U

T vi thp nin tr li y, cng ngh GIS (Geographical Information

Systems) c nhng bc pht trin v ng dng khng ch trong lnh vc a l,

m trong nhiu lnh vc khc ca khoa hc v ca cuc sng hng ngy nh: th

ha, thng mi, pht trin c s h tng, bn in t, hot ng qun s v.v...

Hiu theo cch n gin nht, GIS bao gm cc lp thng tin v mt a im nhm

tng thm kh nng hiu bit v a im ny. T mt gc khc GIS l s ng

dng lin giao gia cng ngh thng tin v l thuyt a l. Mt trong nhng th

mnh ca cng ngh a tin hc ny l kh nng bn ha (mapping) cc thng tin

v cc kiu c s d liu khc nhau nhm a ra mt b c s d liu cho php

ngi s dng c th lu tr, x l, phn tch, la chn, loi tr thng tin v.v, ni

chung l hng lot cc thao tc lin quan n thng tin, phc v cho mt mc

ch chuyn bit no . Hin ti cc nc tin tin GIS c th ni l pht trin

ngy cng mnh tuy nhin Vit Nam GIS cn hn ch v t ph bin v vy chng

em thc hin ti Tm hiu v h thng thng tin a l GIS v cc ng

dng ca GIS.

Mc ch ca ti l tm hiu r hn v GIS v cc ng dng ca GIS, tc

dng ca GIS trong cuc sng hin nay. Gii thiu cho mi ngi bit v GIS v

ng dng ca n trong cc lnh vc. T nhn ra tm quan trng ca n trong

cuc sng hin i vi k thut ngy cng pht trin mnh m .

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MC LC

M U ................................................................................................................2

Chng 1: GII THIU..........................................................................................9

1.1 GIS l g.........................................................................................................9

1.2 Lch s hnh thnh v pht trin n nay: ....................................................10

1.2.1 GIS vi Vit Nam:.................................................................................11

1.3 Gii thiu m hnh cng ngh GIS: .............................................................12

Chng 2: CC THNH PHN CA GIS ..........................................................14

2.1 Phn cng : .................................................................................................14

2.2 Phn mm : ..................................................................................................14

2.3 D liu : ......................................................................................................15

2.4 Con ngi : .................................................................................................15

2.5 Phng php: ..............................................................................................16

Chng 3: CCH THC LM VIC CA GIS ..................................................17

3.1 Tham kho a l: .......................................................................................17

3.2 M hnh vector v Raster: ...........................................................................17

3.2.1 M hnh vector: .....................................................................................18

3.2.2 M hnh raster:......................................................................................18

3.2.3 Phn tch cc yu t: .............................................................................18

Chng 4: NHIM V CA GIS .........................................................................28

4.1. Thu thp d liu: .........................................................................................29

4.2. Lu tr v truy cp d liu. .........................................................................30

4.3 Tm kim v phn tch d liu khng gian....................................................32

4.3.1 Buffer ( Tm kim d liu trong vng khng gian ).................................32

4.3.2 Geocoding ( Tm kim theo a ch ). .....................................................34

4.3.3 Network ( phn tch mng ). ..................................................................35

4.3.4 Overlay ( ph trm hay chng bn )..................................................37

4.3.5 Proximity (Tm kim trong khong cn k). ...........................................39

4.4 Hin th bn .............................................................................................40

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4.5 Xut d liu . ..............................................................................................42

Chng 5 : D LIU CHO GIS............................................................................43

5.1 C 3 cch m hnh d liu trong GIS: .........................................................43

5.1.1 M hnh d liu vector..........................................................................43

5.1.2 M hnh d liu raster ...........................................................................49

5.1.3 M hnh d liu TIN ..............................................................................54

5.2. H qun tr c s d liu ca GIS................................................................58

5.3 Cc thnh phn d liu bn chc nng ....................................................60

Chng 6: CC CNG NGH LIN QUAN .......................................................61

6.1.Thnh lp bn :.........................................................................................61

6.1.1 Desktop mapping:..................................................................................61

6.1.2 Mapinfo:................................................................................................61

6.1.3 ArcGIS desktop: ....................................................................................62

6.2.CAD ( tr gip thit k nh my tnh ).........................................................63

6.3.Vin thm v GPS ( h thng nh v ton cu) ............................................63

6.4. DBMS ( h qun tr c s d liu):..............................................................64

6.5. Internet v network computer ( mng my tnh v truyn thng).................64

Chng7: CC BI TON NG DNG GIS .....................................................65

7.1.Cc lnh vc dng chung, chia s k thut v cung cp d liu cho GIS.......65

7.1.1 Trc a:................................................................................................65

7.1.2 Bn :..................................................................................................65

7.1.3 Vin Thm: ............................................................................................65

7.2.Cc ng dng p dng cng ngh GIS nh l mt cng c qun l , phn

tch d liu v tr gip to quyt nh. ...............................................................66

7.2.1 Qun l v iu tra ti nguyn:..............................................................66

7.2.2 GIS vi mi trng:...............................................................................71

7.2.3 Hot ng v nghin cu khoa hc trong cc trng i hc v vin

nghin cu: ....................................................................................................72

Chng 8: PHT TRIN GIS TRONG NG DNG TNG LAI.....................74

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8.1 GIS trn Internet ( ArcGIS Server )..............................................................74

8.2 Khung GIS chun.........................................................................................75

8.3 Chi ph thp. ................................................................................................75

8.4 Cc ng dng web........................................................................................75

8.5 Cc mu ng dng web. ...............................................................................75

8.6 H tr a min. ............................................................................................76

8.7 H tr nhiu ngn ng lp trnh. ..................................................................76

8.8 Cc phn m rng ca Arc GIS server. ........................................................76

8.9 Cung cp nhiu ti nguyn cho cc lp trnh vin.........................................76

Chng 9: KT LUN .........................................................................................79

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DANH MC HNH NH

Hnh 1.1: M hnh cng ngh GIS.

Hnh 3.1: nh dng d liu Vector v Raster

Hnh 3.2: Quan h ta a l trc quan.

Hnh 3.3: Mt Cu v mt Elip

Hnh 3.4: Mt phng h ta quy chiu

Hnh 3.4: Minh ha cch chiu b mt cong ln mt phng.

Hnh 3.5: Mt chiu hnh trn.

Hnh 3.6: Mt chiu hnh tr.

Hnh 3.7: Cc v tr ca mt phng phng v.

Hnh 4.1: Quan h gia cc nhm chc nng ca GIS

Hnh 4.2: Buffer bn trong mt hnh c bn knh xc nh.

Hnh 4.3: Kt qu tm kim theo a ch.

Hnh 4.4: Kt qu tm kim trn mng giao thng.

Hnh 4.5: Php hp.

Hnh 4.6: Php giao.

Hnh 4.7: Php ng nht.

Hnh 5.1: Bn vi m hnh d liu vector.

Hnh 5.2: i tng point trn bn .

Hnh 5.3: i tng line trn bn .

Hnh 5.4: i tng polyon trn bn .

Hnh 5.5: Buffer

Hnh 5.6: Defference

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Hnh 5.7: Clip

Hnh 5.8: Intersect.

Hnh 5.9: Convex hull.

Hnh 5.10: Sysmetric diffence.

Hnh 5.11: Cut.

Hnh 5.12: Union.

Hnh 5.13: Bn vi d liu Raster.

Hnh 5.14: Hnh chp t my bay.

Hnh 5.15: Bin i t d liu vector sang raster.

Hnh 5.16: Mng cell v bng thuc tnh.

Hnh 5.17: Biu din cc i tng c s trong Raster.

Hnh 5.18: Chuyn i d liu raster sang vector.

Hnh 5.19: Bn vi m hnh d liu TIN.

Hnh 5.20: M hnh cu trc mng TIN.

Hnh 5.21: Biu din TIN t trc i tng c bn.

Hnh 5.22: Tam gic trong mng.

Hnh 5.23: dc b mt tam gic.

Hnh 5.24: Cc i tng hnh hc c bn trong TIN.

Hnh 7.1: bn kim sot mc nc ngm.

Hnh 7.2: Kim sot v phc hi mc nc ngm.

Hnh 7.3: Phn tch h thng song ngi.

Hnh 7.4: Qun l cc lu vc sng.

Hnh 7.5: Kim sot cc ngun nc.

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Hnh 7.6: TP Brno.

Hnh 7.7: M phng ti nguyn t.

Hnh 7.8: Phn tch xu hng xy dng.

Hnh 7.9: Ti nguyn t.

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Chng 1: GII THIU

1.1 GIS l g H Thng tin a l (GIS) l mt cng c my tnh lp bn v phn tch cc

s vt, hin tng thc trn tri t. Cng ngh GIS kt hp cc thao tc c s d

liu thng thng (nh cu trc hi p) v cc php phn tch thng k, phn tch

a l, trong php phn tch a l v hnh nh c cung cp duy nht t cc

bn . Nhng kh nng ny phn bit GIS vi cc h thng thng tin khc v

khin cho GIS c phm vi ng dng rng trong nhiu lnh vc khc nhau (phn tch

cc s kin, d on tc ng v hoch nh chin lc).

Hin nay, nhng thch thc chnh m chng ta phi i mt - bng n dn s,

nhim, ph rng, thin tai - chim mt khng gian a l quan trng.

Khi xc nh mt cng vic kinh doanh mi (nh tm mt khu t tt cho

trng chui, hoc tnh ton l trnh ti u cho mt chuyn xe khn cp), GIS cho

php to lp bn , phi hp thng tin, khi qut cc vin cnh, gii quyt cc vn

phc tp, v pht trin cc gii php hiu qu m trc y khng thc hin

c. GIS l mt cng c c cc c nhn, t chc, trng hc, chnh ph v cc

doanh nghip s dng nhm hng ti cc phng thc mi gii quyt vn .

Lp bn v phn tch a l khng phi l k thut mi, nhng GIS thc

thi cc cng vic ny tt hn v nhanh hn cc phng php th cng c. Trc

cng ngh GIS, ch c mt s t ngi c nhng k nng cn thit s dng thng

tin a l gip ch cho vic gii quyt vn v a ra cc quyt nh.

Ngy nay, GIS l mt ngnh cng nghip hng t la vi s tham gia ca

hng trm nghn ngi trn ton th gii. GIS c dy trong cc trng ph thng,

trng i hc trn ton th gii. Cc chuyn gia ca mi lnh vc u nhn thc

c nhng u im ca s kt hp cng vic ca h v GIS. GIS l mt h thng

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c ng dng rt ln. T nm 1980 n nay c rt nhiu cc nh ngha c a

ra, tuy nhin khng c nh ngha no khi qut y v GIS v phn ln chng

u c xy dng trn kha cnh ng dng c th trong tng lnh vc. C ba nh

ngha c dng nhiu nht :

- GIS l mt h thng thng tin c thit k lm vic vi cc d liu trng

mt h to quy chiu. GIS bao gm mt h c s d liu v cc phng thc

thao tc vi d liu .

- GIS l mt h thng nhm thu thp, lu tr, kim tra, tch hp, thao tc,

phn tch v hin th d liu c quy chiu c th vo tri t.

- GIS l mt chng trnh my tnh h tr vic thu thp, lu tr, phn tch v

hin th d liu bn .

1.2 Lch s hnh thnh v pht trin n nay:

Theo nhiu ti liu cho thy, lch s hnh thnh GIS khng c c th lm

bi l nhng khi nim tng t GIS tn ti ngay t khi xut hin con ngi, t

khi con ngi c nhu cu i li, sinh hot, bun bn,... Mc d vy, s ng gp rt

ln v rt tch cc ca Gio s Roger Tomlinson vo nm 1963 khin th gii

phi cng nhn ng chnh l cha ca GIS (Father of GIS).

Roger Tomlinson l ngi xy dng H thng thng tin a l (HTTTL)

u tin trn th gii. l H thng thng tin a l quc gia Canada (Canada

Geographic Information System). Ngoi ra, ng cn c bit n nh l ngi u

tin a ra thut ng GIS.

Chng ta cng nhau i ngc li lch s thy s ra i k diu ca GIS.

Nh chng ta cng bit, nm 1940 ngnh ha my tnh (Computer Graphics) bt

u hnh thnh v pht trin. S kh khn trong vic s dng cc thit b kinh in

kho st nhng bi ton phc tp hn dn n hnh thnh ngnh Bn my

tnh (Computer Cartographic) vo nhng nm 1960. Cng thi gian ny, nhiu bn

n gin c xy dng vi cc thit b v v in. Tuy nhin, ch khong 10 nm

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sau, nm 1971 khi chip b nh my tnh c ph bin, cc ngnh lin quan n

ha trn my tnh tht s chuyn bin v pht trin mnh.

Tuy nhin, ni n GIS, chng ta cng c th ngh n vic lu tr v truy

vn d liu, c bit l d liu khng gian s. Nhng l thuyt v thc t v c

s d liu v h thng thng tin ra i vo cui nhng nm 60, u nhng nm 70

l mt ng gp khc cho s ra i ca GIS.

Vo nhng nm 1950, cc lc lng qun s bt u s dng vin thm mi

trng (Environmental Remote Sensing) trong cc cng tc c bit. S "chuyn

nhng" cng ngh vin thm t qun s sang dn s vo nhng nm 1960 l mt

ng lc khc thc y GIS.

GIS s khng l GIS nu n khng thc hin cc bi ton phn tch khng

gian (Spatial Analysis). Mt lp bi ton phn tch khng gian kinh in l

chng lp (Overlay). Nhng l lun ng dng i s bn (map algebra) vo

nhng nm 60 trong cc ng dng quy hoch gip b sung thm mt "b phng"

na cho "tn la" GIS.

Tt c nhng tng trn dng nh c hi t vo cng mt thi im.

Roger Tomlinson l mt trong nhng ngi nhy bn n nhn nhng tinh hoa

v chuyn thnh mt GIS.

GIS ngy nay khng ch dng li mc cng ngh m n tin ln nhiu

nc n khoa hc (Geographic Information Science - GISci) v dch v (Geographic

Information Services).

1.2.1 GIS vi Vit Nam: Ti Vit Nam, mc d c bit n t kh sm, nhng mi phi n sau

nm 2000, tc sau khi c c nhng kt qu u tin v vic tng kt chng

trnh GIS quc gia Vit Nam, GIS mi thc s c ch n v bc u pht

trin. Hng lot chng trnh GIS vi s tham gia ca cc trng i hc, cc vin

nghin cu, cc chuyn gia trong v ngoi nc c trin khai. Trong tiu

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biu phi k n D n qun l nc sch H Nam, D n qun l nc Ho

Bnh, D n th nghim trong qun l khch du lch ng Phong Nha hay D n

hp tc vi i hc Qung Nam lm v GIS ca cc chuyn gia Nht Bn... l

cha k mt s d n t nhn, quy m nh l, pht trin t pht theo nhu cu bt

u pht trin v kh rm r trong thi gian gn y...

1.3 Gii thiu m hnh cng ngh GIS:

Mt cch khi qut, c th hiu mt h GIS nh l mt qu trnh sau:

Hnh 1.1: m hnh cng ngh GIS

D liu vo: d liu c nhp t cc ngun khc nhau nh chuyn i

gia cc cch biu din d liu, my qut, hnh nh t v tinh, nh chp

Qun l d liu: sau khi d liu c thu thp v tng hp, GIS cn cung

cp cc thit b c th lu v bo tr d liu nhm m bo: bo mt s liu, tch

hp s liu, lc v nh gi s liu, kh nng duy tr. GIS lu thng tin th gii thc

thnh cc tng d liu ring bit, cc tng ny t trong cng mt h trc to v

chng c kh nng lin kt vi nhau.

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X l d liu: cc thao tc x l d liu c thc hin to ra thng

tin. N gip cho ngi s dng quyt nh cn lm tip cng vic g. Kt qu ca

x l d liu l to ra cc nh, bo co v bn .

Phn tch v m hnh: s liu tng hp v chuyn i ch l mt phn ca

GIS. Nhng yu cu tip theo l kh nng gii m v phn tch v mt nh tnh v

nh lng thng tin thu thp.

D liu ra: mt trong cc phng din cng ngh GIS l s thay i ca

cc phng php khc nhau trong thng tin c th hin th khi n c x l

bng GIS. Cc phng php truyn thng l bng v th c th cung cp bng

cc bn v nh 3 chiu.

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Chng 2: CC THNH PHN CA GIS

2.1 Phn cng :

Phn cng l h thng my tnh trn mt h GIS hot ng. Ngy nay,

phn mm GIS c kh nng chy trn rt nhiu dng phn cng, t my ch trung

tm n cc my trm hot ng c lp hoc lin kt mng.

L cc my tnh in t: PC, mini Computer, MainFrame l cc thit b

mng cn thit khi trin khai GIS trn mi trng mng. GIS cng i hi cc thit

b ngoi vi c bit cho vic nhp v xut d liu nh: my s ho (digitizer), my

v (plotter), my qut (scanner)

2.2 Phn mm :

H thng phn mm GIS rt a dng. Mi cng ty xy dng GIS u c h

phn mm ring ca mnh. Tuy nhin, c mt dng phn mm m cc cng ty phi

xy dng l h qun tr CSDL a l. Dng phn mm ny nhm mc ch nng cao

kh nng cho cc phn mm CSDL thng mi trong vic: sao lu d liu, nh

ngha bng, qun l cc giao dch do ta c th lu cc d liu a l di dng

cc i tng hnh hc trc tip trong cc ct ca bng quan h v nhiu cng vic

khc.

Phn mm GIS cung cp cc chc nng v cc cng c cn thit lu gi,

phn tch v hin th thng tin a l. Cc thnh phn chnh trong phn mm GIS l:

+ Cng c nhp v thao tc trn cc thng tin a l

+ H qun tr c s d liu(DBMS)

+ Cng c h tr hi p, phn tch v hin th a l

+ Giao din ho ngi-my (GUI) truy cp cc cng c d dng

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2.3 D liu :

C th coi thnh phn quan trng nht trong mt h GIS l d liu. Cc d

liu a l v d liu thuc tnh lin quan c th c ngi s dng t tp hp

hoc c mua t nh cung cp d liu thng mi. H GIS s kt hp d liu

khng gian vi cc ngun d liu khc, thm ch c th s dng DBMS (Database

Management System ) t chc lu gi v qun l d liu.

Mt cch tng qut, ngi ta chia d liu trong GIS thnh 2 loi:

D liu khng gian (spatial) cho ta bit kch thc vt l v v

tr a l ca cc i tng trn b mt tri t.

D liu thuc tnh (non-spatial) l cc d liu dng vn bn

cho ta bit thm thng tin thuc tnh ca i tng.

2.4 Con ngi :

Cng ngh GIS s b hn ch nu khng c con ngi tham gia qun l h

thng v pht trin nhng ng dng GIS trong thc t. Ngi s dng GIS c th l

nhng chuyn gia k thut, ngi thit k v duy tr h thng, hoc nhng ngi

dng GIS gii quyt cc vn trong cng vic.

Ngi dng GIS l nhng ngi s dng cc phn mm GIS gii quyt

cc bi ton khng gian theo mc ch ca h. H thng l nhng ngi c o

to tt v lnh vc GIS hay l cc chuyn gia.

Ngi xy dng bn : s dng cc lp bn c ly t nhiu ngun khc

nhau, chnh sa d liu to ra cc bn theo yu cu.

Ngi xut bn: s dng phn mm GIS kt xut ra bn di nhiu

nh dng xut khc nhau.

Ngi phn tch: gii quyt cc vn nh tm kim, xc nh v tr

Ngi xy dng d liu: l nhng ngi chuyn nhp d liu bn bng

cc cch khc nhau: v, chuyn i t nh dng khc, truy nhp CSDL

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Ngi qun tr CSDL: qun l CSDL GIS v m bo h thng vn hnh tt.

Ngi thit k CSDL: xy dng cc m hnh d liu lgic v vt l.

Ngi pht trin: xy dng hoc ci to cc phn mm GIS p ng cc

nhu cu c th.

2.5 Phng php:

Mt h GIS thnh cng theo kha cnh thit k v lut thng mi l c

m phng v thc thi duy nht cho mi t chc.

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Chng 3: CCH THC LM VIC CA GIS

GIS lu gi thng tin v th gii thc di dng tp hp cc lp chuyn

c th lin kt vi nhau nh cc c im a l. iu ny n gin nhng v cng

quan trng v l mt cng c a nng c chng minh l rt c gi tr trong

vic gii quyt nhiu vn thc t, t thit lp tuyn ng phn phi ca cc

chuyn xe, n lp bo co chi tit cho cc ng dng quy hoch, hay m phng s

lu thng kh quyn ton cu.

3.1 Tham kho a l:

Cc thng tin a l hoc cha nhng tham kho a l hin (chng hn nh

kinh , v hoc to li quc gia), hoc cha nhng tham kho a l n

(nh a ch, m bu in, tn vng iu tra dn s, b nh danh cc khu vc rng

hoc tn ng). M ho a l l qu trnh t ng thng c dng to ra cc

tham kho a l hin (v tr bi) t cc tham kho a l n (l nhng m t, nh

a ch). Cc tham kho a l cho php nh v i tng (nh khu vc rng hay

a im thng mi) v s kin (nh ng t) trn b mt qu t phc v mc

ch phn tch.

3.2 M hnh vector v Raster:

H thng thng tin a l lm vic vi hai dng m hnh d liu a l khc

nhau v c bn - m hnh vector v m hnh raster. Trong m hnh vector, thng tin

v im, ng v vng c m ho v lu di dng tp hp cc to x,y. V

tr ca i tng im, nh l khoan, c th c biu din bi mt to n x,y.

i tng dng ng, nh ng giao thng, sng sui, c th c lu di

dng tp hp cc to im. i tng dng vng, nh khu vc bun bn hay

vng lu vc sng, c lu nh mt vng khp kn ca cc im to .

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M hnh vector rt hu ch i vi vic m t cc i tng ring bit,

nhng km hiu qu hn trong miu t cc i tng c s chuyn i lin tc nh

kiu t hoc chi ph c tnh cho cc bnh vin. M hnh raster ddc pht trin

cho m phng cc i tng lin tc nh vy. Mt nh raster l mt tp hp cc

li. C m hnh vector v raster u c dng lu d liu a l vi nhng u

im, nhc im ring, Cc h GIS hin i c kh nng qun l c hai m hnh

ny.

3.2.1 M hnh vector:

Trong m hnh vector, thng tin v im, ng v vng c m ho v lu

di dng tp hp cc to x,y. V tr ca i tng im, nh l khoan, c th

c biu din bi mt to n x,y. i tng dng ng, nh ng giao

thng, sng sui, c th c lu di dng tp hp cc to im. i tng

dng vng, nh khu vc bun bn hay vng lu vc sng, c lu nh mt vng

khp kn ca cc im to .

3.2.2 M hnh raster:

Mt nh raster l mt tp hp cc li. Vi d liu raster th cc tp thuc

tnh thng thng cha d liu lin quan n lp hin tng t nhin thay cho cc

i tng ri rc.

3.2.3 Phn tch cc yu t:

C hai phng php chnh lu tr thng tin bn : GIS lu cc i tng

bn trong nh dng vector v trong nh dng raster.

Trong nh dng vector, cc i tng bn c biu din bi cc i tng

hnh hc c bn point(im), line(ng), polygon(vng). Point dng xc nh cc

i tng khng c hnh dng kch thc c th, hay c kch thc qu nh so vi

t l bn . Line xc nh cc i tng c chiu di xc nh. Polygon xc

nh cc vng, min trn mt t. Trong nh dng ny, thng tin c m t c

tnh chnh xc cao ng thi tit kim khng gian lu tr. Thng tin lu trong nh

19

dng vector ch yu c ng dng trong bi ton v mng, h thng thng tin t

ai.

Trong nh dng raster, cc i tng bn c biu din trong mt chui

cc im nh trong mt li hnh ch nht. Mi im nh c xc nh thng qua

ch s hng v ct trong li. Trong raster, point s c biu din bi mt im

nh n, line c biu din bi mt chui cc im nh lin tip nhau, v polygon

xc nh bi mt nhm cc im nh k st nhau. D liu c lu trong nh dng

ny rt n gin nhng li i hi dung lng b nh ln. Raster ph hp vi cc

dng d liu c ng bin khng r rng. Raster c ng dng nhiu trong phn

tch b mt lin tc.

Hnh 3.1: nh dng d liu Vector v Raster.

3.2.3.1 H to a l v h to quy chiu V tr ca vt th trong khng gian u phi gn lin vi mt h to .

Trong GIS, biu din d liu khng gian ngi ta thng dng 2 h to : h

to a l v h to quy chiu.

H to a l l h to ly mt cu ba chiu bao quanh tri t lm c s. Mt

im c xc nh bng kinh v v ca n trn mt cu.

20

H to quy chiu l h to hai chiu thu c bng cch chiu d liu

bn nm trn h to a l v mt mt phng.

3.2.3.2 H to a l H ta a l s dng b mt hnh cu xc nh v tr ca mt im trn

tri t.

n v o ca h l .

V y l h ta gn lin vi trc tri t nn xc nh v tr ca i

tng ngi ta chia b mt tri t thnh cc ng kinh tuyn v v tuyn. Kinh

tuyn l cc ng cong cch u nhau chy qua hai im cc Bc v Nam, v

tuyn l cc ng trn song song c tm nm trn trc ca tri t. Giao im gia

kinh tuyn v v tuyn to thnh cc li.

Trong s cc kinh tuyn v v tuyn c hai ng quan trng nht c ly

lm gc to l: v tuyn c bn knh ln nht - chnh l ng xch o v

kinh tuyn chy qua vng Greenland nc Anh. Giao im gia hai ng ny l

gc to . Hai ng ny cng ng thi chia tri t lm 4 phn bng nhau: na

Bc v Nam nm pha trn v di ca ng xch o; na ng v Ty nm

pha bn phi v tri ca kinh tuyn gc.

Mt im nm trn mt cu s c hai gi tr to l kinh v v c

xc nh nh trong hnh v trn. Gi tr ny c th c o bng theo c s 10

hoc theo , pht, giy.

Min gi tr ca v : -900 900

kinh : -1800 1800

21

Hnh 3.2: Quan h ta a l trc quan.

Ch : ch trn ng xch o th khong cch mt ca v tuyn mi

bng khong cch mt trn kinh tuyn. Trn cc v tuyn khc khong cch ny

khc nhau rt nhiu. Ngi ta tnh rng mt trn kinh tuyn di khong 111,321

km trong khi 600 trn v tuyn ch c di 55,802 km. Chnh v s khc nhau ny

nn ta khng th o chnh xc c chiu di v din tch ca i tng khi d liu

bn c chiu ln mt phng.

Mt cu v mt Ellipsoid

Trong h to a l c hai b mt hnh cu c s dng l: mt cu

(tuyt i) v mt Ellipsoid.

V b mt ca tri t ca ta khng phi l hnh cu tuyt i m n gn vi

hnh Ellipsoid nn mt Ellipsoid thng c dng biu din. Tuy nhin i khi

ngi ta cng s dng mt cu cng vic tnh ton d dng hn. Khi t ln bn

rt nh < 1:5000.000, t l ny s khc bit gia d liu biu din bng mt

cu v mt Ellipsoid l khng th phn bit c bng mt thng. Lc ny, mt

cu c dng. Nhng khi t l > 1:1.000.000 th ngi ta cn thit phi dng mt

Ellipsoid m bo chnh xc. Do , vic la chn mt cu hay mt Ellipsoid

ph thuc vo mc ch ca bn v chnh xc d liu.

22

Hnh 3.3: Mt Cu v mt Elip

Nu mt cu da trn hnh trn th mt Ellipsoid li c c s l hnh Ellip.

Hnh Ellip c xc nh bi hai bn trc m ta hay gi l: bn trc ln v bn trc

nh. Ta cho Ellip xoay quanh bn trc nh ta s thu c hnh Ellipsoid.

Kch thc v hnh dng ca Ellipsoid c xc nh bi bn trc ln a v bn trc

nh b, hay bi a v h s dt f :

f = (a - b) / a.

V h s f rt nh nn ngi ta thng dng gi tr 1/f

A = 6378137.0 m

1/f = 298.25722563

3.2.3.3 H to quy chiu

thun tin cho s dng ngi ta phi nghin cu cch th hin b mt tri

t ln trn mt phng ca bn . Do phi thc hin php chiu b mt cong

ca tri t ln mt phng v h to quy chiu ra i. H to ny lun ly h

to a l lm c s.

H to quy chiu c c trng bi hai trc x theo phng ngang v y

theo phng thng ng. Gc to l giao im ca hai trc ny. Hai trc giao

nhau ng thi chia mt phng lm 4 phn tng ng vi 4 phn trong h to a

l. Mt im trn mt c xc nh c xc nh bi cp gi tr (x, y).

23

Hnh 3.4: Mt phng h ta quy chiu

C rt nhiu php chiu b mt cong ca tri t ln mt phng song v c

bn ta c th hiu nh sau. Ly mt mnh ba cun xung quanh b mt cu trong h

to a l theo mt hnh tr ng. T tm ca b mt cong ta v cc tia ct cc

im giao gia kinh tuyn v v tuyn, ng thi ko di ct mt tr. Thc cht ca

vic ny l chiu cc li ln b mt phng. M t ba ra ta c kt qu ca php

chiu. Nhn vo tm ba ta nhn thy, cc li thay i kh nhiu (bin dng),

co li hoc dn ra. Cng xa ng xch o th s bin dng cng ln. iu ny gy

nn s thay i v hnh dng, kch thc, khong cch ca d liu khng gian.

24

Hnh 3.4: Minh ha cch chiu b mt cong ln mt phng.

Sau ngi ta dng cc cng thc ton hc tng ng to ca b mt

cong ln to mt phng chiu.

Cc php chiu khc nhau gy ra cc bin dng bn khc nhau nn vic

s dng php chiu no l da vo mc ch ca bn v chnh xc ca d

liu.

Cc php chiu c bn

Trong phn ny ta s tm hiu ba php chiu c bn v thng c s dng

nht l php chiu vi mt chiu: mt hnh nn, mt hnh tr v mt phng

phng v.

Bc u tin khi tin hnh php chiu ny l to ra mt hay mt tp cc

im tip xc. Cc im tip xc ny c gi l cc tip im hay l tip tuyn

(trong trng hp l ng thng). Cc im ny c vai tr rt quan trng, v

bin dng ca php chiu trn nhng im ny bng khng. bin dng s tng

khi khong cch gia im chiu v im tip xc tng.

25

Mt hnh nn

thc hin php chiu ny ngi ta cho dng mt mt hnh nn p ln

b mt cu. ng thng tip xc gia mt nn v mt cu l mt v tuyn v c

gi l v tuyn chun. Cc ng kinh tuyn sau khi chiu mt nn s thnh nhng

ng thng ng, cc ng v tuyn s to thnh nhng ng trn.

Sau khi thc hin php chiu, ngi ta s ct hnh nn dc theo mt kinh tuyn bt

k, lc ny ta s c kt qu ca php chiu trn b mt nn. S giao nhau gia

nhng ng thng v cung trn s to nn mt mt li. ng thng i din vi

ng ct c gi l kinh tuyn trung tm.

Cng xa v tuyn chun bin dng cng tng. Do tng chnh xc ngi

ta ct b phn nh ca mt nn hay ta khng tin hnh chiu ln vng ny. Php

chiu ny thng c dng cho vic chiu cc vng c cc v tuyn trung bnh

chy qua v hng theo chiu ng - ty.

Hnh 3.5: Mt chiu hnh trn.

Mt hnh tr

Ging nh php chiu mt nn, php chiu ny cng c mt ng thng

tip tuyn. Khi s dng mt tr, ngi ta phn lm 3 loi tu thuc vo v tr tng

i ca mt tr so vi mt cu:

Hnh tr c t theo phng thng ng v tip xc vi mt cu theo mt

v tuyn, thng l ng xch o. Gi l php chiu Mercator.

26

Hnh tr c t theo phng nm ngang, ng thng tip xc l mt

kinh tuyn. Gi l php chiu Transverse.

Hnh tr t xin v tip xc vi mt cu theo mt ng trn c bn knh

ln nht (bng vi bn knh ng xnh o). Gi l php chiu Oblique.

Php chiu thng c s dng nht l Mercator. Trong php chiu ny,

cc ng kinh tuyn s c chiu thnh nhng ng thng ng cch u nhau,

cc ng v tuyn s tr thnh nhng ng nm ngang khong cch khng u

nhau; tng dn v pha hai cc. Do bin dng s tng dn v pha hai cc. Sau

khi thc hin php chiu, ngi ta s ct mt hnh tr dc theo mt kinh tuyn, tri

ra trn mt phng ta s thu c kt qu.

Hnh 3.6: Mt chiu hnh tr.

Mt phng phng v

L php chiu d liu bn ln mt mt phng tip xc vi mt cu. im

tip xc ny c th l: nm ti hai cc, ti ng xch o, hoc ti mt v tr bt k

nm gia. V tr ca im tip xc cho ta bit v tr tng i ca mt phng chiu

vi mt cu v to nn ba kiu chiu khc nhau: polar, equatorial v oblique.

27

Hnh 3.7: Cc v tr ca mt phng phng v.

Mt phng chiu tip xc vi cc ca mt cu l kiu chiu n gin nht v

cng hay dng nht. Trong php chiu ny, cc ng kinh tuyn s c chiu

thnh mt chm ng thng giao nhau im cc, v tuyn l cc ng trn c

cng tm l cc ca mt cu. Gc gia cc ng kinh tuyn c bo tn.

28

Chng 4: NHIM V CA GIS

Mt h GIS phi m bo c 6 chc nng c bn sau:

o Capture: thu thp d liu. D liu c th ly t rt nhiu ngun, c th l bn

giy, nh chp, bn s

o Store: lu tr. D liu c th c lu di dng vector hay raster.

o Query: truy vn (tm kim). Ngi dng c th truy vn thng tin ho

hin th trn bn .

o Analyze: phn tch. y l chc nng h tr vic ra quyt nh ca ngi

dng. Xc nh nhng tnh hung c th xy ra khi bn c s thay i.

o Display: hin th. Hin th bn .

o Output: xut d liu. H tr vic kt xut d liu bn di nhiu nh

dng: giy in, Web, nh, file

Hnh 4.1: Quan h gia cc nhm chc nng ca GIS

29

4.1. Thu thp d liu:

Thu thp d liu l qu trnh thu nhn d liu theo khun mu c p dng

cho GIS. Mc n gin nht ca thu thp d liu l chuyn i khun dng mu

c sn t bn ngoi. Trong trng hp ny, GIS phi c cc tin ch hiu c

cc khun dng mu d liu chun khc nhau trao i. GIS cn phi c kh nng

nhp cc nh bn . Trong thc t, nhiu k thut trc a c p dng thu

thp d liu th, bao gm thu thp d liu v b mt tri t nh a hnh, a cht

hc v thm thc vt nh trc a o c hay nh chp t v tinh, my bay. Cc d

liu nh kinh t - x hi thu thp t iu tra phng vn hay chuyn i t cc bi t

liu vit. Bn v bng tay trn giy phi c s ho sang dng raster. Vic s

dng nh v tinh hay nh chp t my bay c xem l ngun d liu quan trng

khi nghin cu ti nguyn thin nhin v o v bn a hnh.

a s ngun gc thng tin khng gian l cc bn in hay bn di

khun mu tng t. cc d liu ny c s dng trong GIS th chng cn

c s ho. mc th cng th ch c th s ho cc c trng bn v nhp

thuc tnh m t cc c trng . Cn mc t ng ho cao hn l s ho bn

bng my qut nh pht sinh nh s bn y . u ra ca my qut l ma

trn ca cc gi tr im nh 2D, c th c s dng cho cng vic vector ho

to ra bn m ho d liu, kim chng v sa li c c d liu ph hp.

Ni chung, cng vic thu thp d liu hay lm d liu bn l nhim v

kh khn v l quan trng nht khi xy dng cc ng dng GIS.

Qu trnh thu thp d liu lun gn lin vi qu trnh x l d liu. Chng ta

c ba m hnh quan nim ca thng tin khng gian l: m hnh hng i tng,

mng v b mt. Qu trnh phn tch trn c s cc cch nhn khc nhau i hi d

liu phi c biu din v t chc cho ph hp. V vy cn cung cp phng tin

cho ngi s dng GIS thay i cu trc d liu thch nghi vi cc yu cu khc

nhau. iu ny i hi cn phi c cc chc nng thay i cch biu din, thay i

30

phn lp, lm n gin ho hay tng qut ho d liu, bin i gia h thng trc

to khc nhau v bin i cc php chiu bn . Cc thao tc ny c xem l

tin phn tch khng gian. Mc x l d liu th khc nhau ph thuc vo mc

ch ca ng dng GIS.

Mt s cng c phn tch ca GIS ph thuc cht ch vo cc m hnh d

liu raster, do n i hi qu trnh bin i m hnh d liu vector sang d liu

raster, qu trnh ny c gi l raster ho. Mt s cng c phn tch khc li lm

vic ch yu vi m hnh vector, nn i hi qu trnh bin i ngc t raster sang

vector, hay cn gi l vector ho. Raster ho l qu trnh phn tch ng (line) hay

min (polygon) thnh cc im nh (pixel). Ngc li, vector ho l qu trnh tp

hp cc im nh to thnh ng hay min. D liu ban u ca ta thng

thng l di dng raster nn nu d liu khng c cu trc tt th vic nhn dng

mu s rt phc tp.

Khi so snh d liu t cc ngun khc nhau, vn thng ny sinh l s

dng hai hay nhiu phn lp m ho cho cng hin tng. nhn ra cc kha

cnh khc nhau ca hin tng vi mc chi tit khc nhau, cn phi c tin trnh

xp x ho bin i v cng mt phn lp.

Trong vic tch hp d liu bn , vn ny sinh l h thng to ca

chng c o, v trn c s nhiu php chiu bn khc nhau. Cc d liu ny

khng th tch hp trn cng bn nu khng bin i chng v cng mt h trc

to .

4.2. Lu tr v truy cp d liu.

Lu tr d liu lin quan n to lp CSDL khng gian ( ho, bn ). Ni

dung ca CSDL ny c th bao gm t hp d liu vector hoc/v d liu raster, d

liu thuc tnh nhn din hin tng tham chiu khng gian. Thng thng d

liu thuc tnh ca GIS trn c s i tng c lu trong bng, chng cha kho

chnh l mt ch danh duy nht tng ng vi i tng khng gian, km theo

nhiu mc d liu thuc tnh khc. Ch danh i tng khng gian duy nht c

31

dng lin kt gia d liu thuc tnh v d liu khng gian tng ng. Trong

bng thuc tnh cng c th bao gm c gi tr khng gian nh di ng, din

tch vng m chng c dn xut t biu din d liu hnh hc.

Vi d liu raster th cc tp thuc tnh thng thng cha d liu lin quan

n lp hin tng t nhin thay cho cc i tng ri rc. Vic la chn m hnh

raster hay m hinh vector t chc d liu khng gian c thc hin khi thu thp

d liu v mi m hnh tng ng vi cc tip cn khc nhau. Thng thng CSDL

GIS cho kh nng qun tr c hai m hnh khng gian ni trn, khi xy dng CSDL

khng gian th nht thit phi lin kt bng d liu lin quan n hin tng tng

ng.

Theo thut ng ca h qun tr CSDL th cc m hnh vector v raster c

xem nh nhng th d ca m hnh quan nim. Chng m t cc quan nim lin

quan n ng dng th gii thc c biu din trong CSDL. Cc m hnh quan

nim c m t theo nhiu cp bc tru tng, trong cc m hnh vector v

raster l mc tru tng thp nht. Chng gn vi biu din d liu my tnh hn

cc m hnh trn c s d liu i tng, mng v b mt. Khi nim m hnh d

liu lgic c s dng cp n cch m DBMS t chc m hnh quan nim

thnh tp, bn ghi, ch s. Ngy nay, cng ngh CSDL truyn thng khng cn

thch hp vi vic qun l d liu a l. Mt s h GIS c s dng rng ri

xy dng CSDL trn c s t hp m hnh quan h qun l thuc tnh phi hnh hc

v lc chuyn dng, phi quan h lu tr, x l d liu khng gian. Mt vi

GIS khc li dng cc phng tin ca lc lu tr CSDL quan h qun l

c hai loi d liu hnh hc v phi hnh hc.

Phng tin truy nhp trong CSDL GIS bao gm c phng tin c sn ca

CSDL quan h chun v kh nng xy dng cu hi truy vn tm thng tin m

gi tr ca chng bng hoc nm trong khong xc nh. c tnh c bit theo v tr

i vi h to no v theo cc quan h khng gian. Do nhu cu khai thc

thng tin trn CSDL khng gian thng bao gm phng php ch s khng gian

32

c bit. Cu hi khng gian thng l tm ra i tng nm trong hay trn cc bin

ca ca s hnh ch nht. Khai thc d liu trn c s v tr hay quan h khng gian

c xem nh l nn tng ca thm nhp CSDL GIS.

4.3 Tm kim v phn tch d liu khng gian.

Tm kim v phn tch d liu khng gian. y l chc nng ng vai tr rt

quan trng trong GIS. N to nn sc mnh thc s ca GIS so vi cc phng

php khc. Tm kim v phn tch d liu khng gian gip tm ra nhng i tng

ho theo cc iu kin t ra hay h tr vic ra quyt nh ca ngi dng GIS.

C rt nhiu cc phng php tm kim v phn tch d liu khng gian, cc

phng php khc nhau thng to ra cc ng dng GIS khc nhau. Sau y l mt

s phng php c dng ph bin nht:

4.3.1 Buffer ( Tm kim d liu trong vng khng gian )

Buffer hay cn gi l truy vn khng gian trn c s cc quan h khng gian

gia cc i tng. Cc quan h ny thng thng ni ln v tr tng i ca i

tng ny vi i tng kia. Phng php buffer c chia lm nhiu loi (php

ton) khc nhau, nhng cch thc x l th lun tun theo cc bc c bn sau y:

Chn ra mt hay nhiu i tng trn bn , gi l cc i tng gc.

p dng mt quan h khng gian tm ra cc i tng khc m c quan h

c bit vi cc i tng gc.

Hin th tp i tng tm thy c trn d liu khng gian v thuc tnh

Mt s php ton buffer thng dng

Tm cc i tng nm bn trong cc i tng khc. Php ton ny xc nh quan

h bao kn gia cc i tng khng gian. ng thng bao gm nhiu im, mt

a gic (polygon) c th bao gm nhiu ng thng hoc gm cc a gic con

khc.

33

Tm cc i tng ct cc i tng khc. Php ton ny xc nh cc i

tng c giao im hay nm chng ln cc i tng khc. Hai a gic giao nhau

nu chng c mt min chung. Hai ng thng ct nhau nu chng c mt im

chung. Mt ng thng giao vi mt a gic khi n nm mt phn hay ton b

trong a gic.

Tm cc i tng lin k vi cc i tng khc. y l kiu tm kim trong

cc i tng c chung ng bao (bin). Quan h ny ch p dng cho ng

thng hoc a gic.

Tm cc i tng nm bn trong hoc bn ngoi mt khong cch xc nh. Kiu

tm kim ny c s dng trong vic xc nh cc i tng xung quanh mt hay

nhiu cc im mc. Qu trnh thc hin bao gm vic to ra mt vng m quanh

cc im mc ny v sau xc nh cc i tng cn c vo v tr ca chng so

vi vng m to ra.

Mt bi ton rt in hnh cho phng php buffer ny l bi ton v Nh

my ho cht v cc bnh vin. Mc ch ca bi ton l xc nh cc v tr thun

tin nht trn bn cho vic di di cc bnh vin trong trng hp nh my ho

cht gp s c. Cc nh my ho cht v bnh vin c biu din trn bn bng

cc i tng im (points). Mi nh my bao gm cc thng tin chi tit v loi ho

cht sn xut v mc pht tn cht c ra mi trng trong cc iu kin thi tit

khc nhau. Khi c s c, vng nguy him cn di di s c th hin trn bn .

T , chng ta c th bit c nn chuyn bnh vin n vng no l an

ton v thun tin nht.

34

Hnh 4.2: Buffer bn trong mt hnh c bn knh xc nh.

4.3.2 Geocoding ( Tm kim theo a ch ).

Mt i tng trn bn bao gi cng c biu din bng mt kiu d

liu ho. Phn ho ny c th thu c bng cch s ho hay qut nh bn .

Tuy nhin, khi ta c bn (bn s), chng ta cng c th xc nh

c phn ho biu din i tng hay l v tr, hnh dng ca i tng thng

qua cc d liu m t v tr ca n v d: s nh, tn ng, tn qun

Geocoding (hay address matching) l mt tin trnh nhm xc nh cc i tng

trn c s m t v tr ca chng. y l mt k thut rt ni ting, c mt trong rt

nhiu ng dng ca GIS.

Ngi ta gi mt geocoding service l qu trnh chuyn i ton b m t

thuc tnh v v tr sang m t khng gian.

tm c v tr thng qua a ch, geocoding service phi tham chiu n

t nht mt ngun d liu bao gm c thng tin v a ch (thuc tnh) v thng tin

khng gian (v tr, hnh dng). D liu ny c gi l d liu tham chiu. Cc

gocoding service c th thao tc trn nhiu kiu d liu tham chiu khc nhau.

Sau khi geocoding d liu tham chiu (tc l nh x m t thuc tnh vo m t

khng gian). Ta c th nhp a ch ca i tng cn tm. Quy trnh x l tri qua

cc bc sau:

35

Chun ho gi tr a ch va nhp vo bng cch tch n thnh cc thnh

phn a ch nh.

Geocoding service sau s tm trong ngun d liu tham chiu xc nh

cc i tng c cc thnh phn a ch tng ng vi d liu nhp vo. Mi kiu

geocoding service s quy nh cc nh dng ca cc thnh phn a ch ny.

Tp kt qu tr v s c gn cc trng s (im) tm ra kt qu gn

ng nht.

Geocoding service s nh du i tng va c tm thy trn bn

bng mt i tng ho.

Hnh 4.3: Kt qu tm kim theo a ch.

4.3.3 Network ( phn tch mng ).

Networks l k thut c ng dng rt rng ri trong giao thng, phn phi

hng ho v dch v, vn chuyn nc hay xng du trong cc ng ng di, trao

i thng tin qua mng vin thng Trong GIS, networks c m hnh di dng

cc th mt chiu hay mng hnh hc. Mng hnh hc ny bao gm cc i tng

36

ang c hin th trn bn , mi i tng ng vai tr l cnh hoc nt trong

mng.

Trong GIS thit lp nn mi quan h gia nt - cnh v cnh - cnh ta cn

to cc topology cho c s d liu. Topology c hiu l mi quan gia cc i

tng trong bng d liu. Quan h topology gia cc i tng gn ging quan h

gia cc bng (relationship).

Chng ta c hai kiu lin kt l nt - cnh v cnh - cnh. Nt - cnh l lut

lin kt c thit lp gia mt nt ca i tng kiu A vi mt cnh ca i

tng kiu B. Cnh - cnh l lut lin kt gia mt cnh ca i tng kiu A v

mt cnh ca i tng kiu B qua mt tp cc nt.

Khi to topology v xc lp lut lin kt, mt mng lgic c hnh

thnh. Lc ny ta c th p dng cc thut ton v mng gii quyt cc bi ton

t ra.

Hnh 4.4: Kt qu tm kim trn mng giao thng.

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4.3.4 Overlay ( ph trm hay chng bn ).

y l k thut kh nht v cng l mnh nht ca GIS. Overlay cho php ta

tch hp d liu bn t hai ngun d liu khc nhau. Ngi ta nh ngha:

Overlay l qu trnh chng kht hai lp d liu bn vi nhau to ra mt lp

bn mi. iu ny tng t nh vic nhn hai ma trn to ra mt ma trn

mi, truy vn hai bng c s d liu to ra bng mi, vi overlay l gp hai lp

trn bn to ra bn mi. Overlay thc hin iu ny bng cch kt hp

thng tin mt lp ny vi mt lp khc ly ra d liu thuc tnh t mt trong hai

lp.

Ngi ta chia overlay thnh ba dng phn tch khc nhau:

Point-in-polygon: chng kht hai lp point v polygon, u ra l lp point

Line-in-polygon: chng kht hai lp line v polygon, u ra l lp line

Polygon-in-polygon: chng kht hai lp polygon v polygon, u ra l lp

polygon

Mt bi ton rt in hnh cho k thut ny l bi ton v kim tra tnh hnh

ngp lt ca cc tha t trong mt vng c thin tai. y chng ta thy c hai

lp: mt lp cho bit tnh trng l lt trong vng, mt lp thuc v t ai. Thng

thng hai lp ny s nm trn hai bn khc nhau v mc ch s dng ca

chng khc nhau. Khi cn bit tnh trng ngp lt ca tng tha t, ngi ta tin

hnh chng kht hai lp bn . Lc ny thng tin v tnh trng ca tha t s c

ly t lp l lt ch khng phi ly t lp tha t v lp tha t khng cha cc

thng tin ny. V d ny m t bi ton thuc loi polyon-in-polygon.

Qua bi ton chng ta c th thy mt iu rng hai lp m ta a vo

overlay phi c s thng nht vi nhau. Thng nht v h quy chiu, thng nht v

t l, c c iu kin ny ta mi tin hnh overlay c.

Qu trnh overlay thng c tin hnh qua 2 bc:

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Xc nh ta cc giao im v tin hnh chng kt hai lp bn ti giao

im ny

Kt hp d liu khng gian v thuc tnh ca hai lp bn .

Cc php ton overlay bao gm: php hp (Union), php giao (Intersect) v php

ng nht (Identity)

Php hp

Hot ng nh ton t Or , u vo l hai lp bn kiu l polygon

Kt qu u ra l mt lp bn mi bng cch overlay hai min d liu du vo

v d liu thuc tnh ca chng. iu kin: min d liu phi l polygon

Hnh 4.5: Php hp.

Php giao

Hot ng nh ton t And .

To ra mt vng bao ph mi bng cch overlay hai tp d liu u vo

Kt qu u ra bao gm phn d liu thuc vo c hai tp d liu u vo

Hnh 4.6: Php giao.

Php ng nht

To ra mt vng bao ph mi bng cch overlay hai tp d liu u vo.

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Kt qu u bao gm ton b phn d liu ca lp u tin v ch nhng phn no

ca lp th hai c chng kht.

Hnh 4.7: Php ng nht.

4.3.5 Proximity (Tm kim trong khong cn k).

Proximity l php tm kim trn c s o khong cch quanh hoc gia cc

i tng. Khong cch ny c tnh theo khong cch Euclidean. C 3 phng

php phn tch proximity:

Phng php th nht l tm kim ni dung trong vng, trong vng tm

kim c xc nh bi xp x ti hin tng c sn, chnh l phng php

buffer. Vic tm kim ny c thc hin trong vng to bi m rng i tng cho

trc theo mt khong cch cho trc. Trong GIS vng ny c gi l vng m,

n c xy dng xung quanh i tng im, i tng ng hay i tng

vng. Trong cc h thng trn c s raster th vic to lp vng m dc thc hin

nh chc nng spread.

Phng php th hai ca tm kim cn k l tm ra cc vng ni trc tip vi

i tng xc nh trc, chng hn nh tm cc mnh t lin k vi mnh t s

xy dng nh my.

Phng php th ba ca tm kim cn k xy ra khi cn phi tm kim nhng

vng gn nht ti tp cc v tr mu phn tn khng u. Cc mu thng l cc

im. Tm kim ny thc hin bng cch to lp a gic Thiessen, n xc nh cc

vng xung quanh mi im m gn im ny hn mi im khc. S a gic

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Thiessen cn c gi l s Voronoi. Chng c s dng lp ra bn s

dng t cc mu t cch bit.

4.4 Hin th bn

Trong GIS, cc i tng c s d liu khng gian trong th gii thc c

m t di dng bn . im mnh ca cc h thng GIS l kh nng th hin ni

dung a l cc mi quan h v khng gian gia chng . Cch m GIS hin th cc

i tng thc th c quy ra lm 4 loi i tng s c bn:

i tng kiu im (point)

i tng kiu ng (line, polyline)

i tng kiu vng (area, polygon)

i tng kiu m t (annotation, text, symbol).

Cch phn nh cc i tng trn bn :

* Bn th hin cc i tng a l thng qua m t bng tp hp cc thnh

phn ca: ng, mu sc, k hiu v t ng

* Cc thng tin ho v m t cho chng ta bit v v tr a l v cc thuc

tnh ca cc i tng a l.

* M hnh d liu s phn nh li cc v tr, tnh cht v cc quan h khng gian

di dng s

* Bn s lu tr d liu theo loi i tng. Bn s lu theo loi i tng

di y:

* im (Points): i tng n c v tr.V d Trm cu ho, nh Ging

* ng (Arcs): Cc i tng dng tuyn. V d ng s, sng, ng in

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* Vng (Polygons): Vng c din tch, nh ngha bi ng bao . V d tha

loi t .

phn nh ton b cc thng tin cn thit ca bn di dng i tng

s, cc i tng a l cn c phn nh theo cu trc phn mnh v phn lp

thng tin.

Cu trc phn mnh:

Mt i tng a l v mt khng gian c th lin tc trn mt phm vi

rng. Tuy nhin trong c s d liu GIS, do hn ch v cc l do k thut nh kh

nng lu tr, x l, qun l d liu m cc i tng a l lu tr di dng cch

mnh (mapsheet, tile). Tuy nhin khi nim chia mnh trong c s d liu GIS

khng hon ton ng nht vi khi nim chia mnh bn thng thng. Mt

mnh (tile) trong c s d liu GIS c th c hnh dng bt k min sau cho ph

hp vi kh nng qun l v x l ca h thng. Trong mt s h thng GIS c,

ngi dng phi t qun l cch chia mnh ca mnh. Tuy nhin xu hng hin

nay, cc h thng GIS cung cp nhng cng c cho php ngi s dng t ng

qun l cc mnh trong c s d liu. Mt s GIS tin b hn, da trn cc k thut

mi ca cng ngh hng i tng, v mt vt l, cc i tng a l b chia ct

theo tng mnh, nhng i vi ngi s dng, cc i tng l lin tc khng b

chia ct.

Cu trc phn lp thng tin:

Mt trong nhng bc quan trng xy dng c s d liu GIS l phn loi

cc lp thng tin (layer, class). H thng GIS lu tr cc i tng a l theo cc

lp thng tin. Mi lp thng tin lu tr mt loi cc i tng c chung mt tnh

cht, c im ging nhau. Thit k cc lp thng tin rt quan trng i vi bt k

mt h thng GIS no. Cch phn lp thng tin s nh hng rt ln n tnh hiu

qu, kh nng x l v s dng lu di ca c s d liu khng gian.

Mt s nguyn tc khi thit k cc lp thng tin:

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- C cc lp thng tin c bn: cc ng dng khc nhm cn n nhng lp thng tin

c bn (thng tin nn) V d nh:

+ Lp thng tin c s ton hc bn : im khng ch, khung, im cao, trc

a nh nc, v..v..

+ Lp thng tin v a hnh

+ Lp thng tin v h thng thu vn

+ Lp thng tin v h thng ng giao thng

cc lp thng tin chuyn : Tu tng ng dng v yu cu c th trc mt,

vic chn la cc lp thng tin chuyn c lu tr trong c s d liu v th t

nhp vo l quan trng. N nh hng trc tip n gi thnh v thi gian xy dng

c s d liu GIS

Gp cc i tng thnh mt lp thng tin: khng qu chi tit ( trnh c qu

nhiu lp thng tin phi qun l) cng nh khng qu tng qut (kh khn khi

mun x l ring bit).

4.5 Xut d liu .

Hu ht cc phn mm GIS u h tr vic kt ni v truy xut d liu di

nhiu nh dng : giy in, web, hnh nh, file

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Chng 5 : D LIU CHO GIS

Trong cc m hnh biu din d liu ca GIS, chng ta thng nhc n mt

khi nim l feature. Theo nh ngha ca ISO (International Standard

Organization): Feature l s tru tng ho ca mt s vt trong th gii thc.

Trong , thuc tnh ca feature chnh l c im m t feature .

5.1 C 3 cch m hnh d liu trong GIS:

Modelling with vector data: m hnh d liu vector

Modelling with taster data: m hnh d liu raster

Modelling with triangulated data: m hnh TIN

5.1.1 M hnh d liu vector.

M hnh d liu vector xem cc s vt, hin tng l tp cc thc th khng

gian c s v t hp ca chng. Trong m hnh 2D th cc thc th c s bao gm:

im (point), ng (line), vng (polygon). Cc thc th s ng c hnh thnh

trn c s cc vector hay to ca cc im trong mt h trc to no .

Loi thc th c s c s dng ph thuc vo t l quan st hay mc khi

qut. Vi bn c t l nh th thnh ph c biu din bng im (point),

ng i, sng ngi c biu din bng ng (line). Khi t l thay i ko theo

s thay i v thc th biu din. Thnh ph lc ny s c biu din bi vng c

ng ranh gii. Khi t l ln hn, thnh ph c th c biu din bi tp cc thc

th to nn cc i tng nh ca, ng s, cc trnh tin ch, Ni chung m

hnh d liu vector s dng cc on thng hay cc im ri rc nhn bit cc v

tr ca th gii thc.

Trong m hnh vector ngi ta tru tng ho cc s vt hin tng v gi

chng l cc feature (nh phn nh ngha mc 2.1). Cc feature c biu din

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bng cc i tng hnh hc: point, line, polygon. Cc biu din ny p dng cho

nhng i tng n c hnh dng v ng bao c th.

Hnh 5.1: Bn vi m hnh d liu vector.

Trong cch biu din ny, ngi ta nh ngha:

Feature l mt i tng trn bn c hnh dng v v tr xc nh, c cc thuc

tnh cng vi hnh vi c th.

Feature Class l mt tp cc feature c cng kiu tc l tp cc point, line, hay

polygon. Cc feature class tng ng vi mt lp trn bn .

Feature Dataset l tp cc feature class hay tp hp cc lp trn cng mt h to

. Feature dataset tng ng vi mt bn .

Cc thnh phn d liu

Trong feature dataset, mi point c lu di mt to n tng ng, line c

lu di mt chui cc im c to x, y cho trc, polygon c lu thnh mt

tp cc im c to x, y xc nh nhng on thng v ng kn.

Points :biu din cc feature khng c min bao hay di, nhiu khi n biu din

cc feature c kch thc qu nh so vi t l ca bn .

Hnh 5.2: i tng point trn bn .

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Lines : dng biu din cc feature c chiu di xc nh nhng khng c min

bao hay nhng feature rt hp so vi t l bn

Hnh 5.3: i tng line trn bn .

Polygons : c dng biu din cc feature c min bao xc nh: rung t, ao,

h hay cc n v hnh chnh

Hnh 5.4: i tng polyon trn bn .

Cc php ton phn tch khng gian trn m hnh Vector

GIS cung cp rt nhiu php ton phn tch khng gian trn m hnh d liu vector.

Cc php ton ny da trn c s so snh lgic tp cc i tng ny vi tp i

tng khc.

5.1.1.1. Buffer

Cho trc mt i tng v mt gi tr khong cch, php ton buffer s to ra mt

vng m l mt polygon bao ph xung quanh tt c cc im m khong cch t

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chng n i tng nh hn hoc bng khong cch ra.

Hnh 5.5: Buffer

5.1.1.2. Defference

Cho trc hai i tng giao nhau l i tng c s v i tng so snh. Php

ton difference s to ra mt i tng mi trong gi nguyn phn ca i tng

c s khng nm trong i tng so snh.

Hnh 5.6: Defference

5.1.1.3. Clip

Cho trc mt i tng v mt hnh ch nht. Php ton clip s to ra mt i

tng mi bng cch ct i tng u vo theo hnh ch nht.

Hnh 5.7: Clip

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5.1.1.4. Intersect

Cho trc hai i tng. Php ton intersect s to ra mt i tng mi

chnh l phn giao gia hai i tng.

Hnh 5.8: Intersect

5.1.1.5. convex hull.

Hnh 5.9: Convex hull

Cho trc mt i tng, php ton convex hull s to ra mt i tng mi

l mt polygon bng cch ni tt c cc im bin ca i tng . Ni cch

khc, y l polygon nh nht bao kn i tng.

5.1.1.6. Symmetric difference

Php ton symmetric difference s tin hnh so snh v tr hai i tng v

to ra mt i tng mi t hai i tng ban u v b i phn giao gia chng.

Hnh 5.10: Sysmetric diffence

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5.1.1.7. Cut.

Cho mt ng cong v mt i tng, php ton cut s tch i tng ny

thnh hai phn na phi v na tri theo hng ca ng cong.

Point v multipoint khng c p dng. Line v polygon phi ct ng cong.

Hnh 5.11: Cut

5.1.1.8. Union.

Php ton ny tin hnh so snh v tr tng i ca hai i tng v tr v

mt i tng trn c s hp hai i tng ban u.

Hnh 5.12: Union

M hnh d liu vector cho ta nhiu thao tc hn trn cc i tng so vi

m hnh raster. Vic tnh din tch, o khong cch ca cc i tng c thc

hin bng cc tnh ton hnh hc t to ca cc i tng thay v vic tnh ton

trn cc im nh ca m hnh raster. Cc thao tc trong m hnh ny ni chung

thng chnh xc hn. Th d, tnh din tch, chu vi ca mt vng no trn c s

a gic s chnh xc hn vic m cc im nh trn bn c cc php chiu khc

nhau. Mt s thao tc m hnh ny cng thc hin nhanh hn nh tm ng i

trong mng li giao thng da trn l thuyt th. Tuy nhin, mt s thao tc

khc th m hnh ny s chm hn so vi m hnh raster, chng hn khi thc hin

np chng cc lp ca bn , cc thao tc vng m.

49

M hnh d liu vector hnh thnh trn c s quan st i tng ca th gii

thc. Quan st cc c trng theo hng i tng l phng php t chc thng

tin trong cc h GIS nh hng cc h thng qun tr CSDL. Chng ti u trong

vic lu tr s liu bn v ch cn lu cc ng bin ca cc c trng m

khng cn phi lu ton b vng ca chng. Do cc thnh phn ho biu din

cc c trng ca bn lin kt trc tip vi cc thuc tnh ca CSDL nn ngi

dng d dng tm kim v hin th cc thng tin t CSDL.

5.1.2 M hnh d liu raster

M hnh raster biu din cc c trng a l bng cc im nh (pixel). D

liu raster gn lin vi d liu dng nh hoc d liu c tnh lin tc cao. D liu

raster c th biu din c rt nhiu cc i tng t hnh nh b mt t n nh

chp t v tinh, nh qut v nh chp. nh dng d liu raster rt n gin nhng

h tr rt nhiu kiu d liu khc nhau.

Hnh 5.13: Bn vi d liu Raster.

Ngun d liu raster

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nh chp t v tinh, nh chp t my bay, nh qut, nh chp. Trong nh chp

t v tinh l cch ly d liu tn km nht nhng li c ngha to ln trong vic

nghin cu tnh hnh bin i ca cc s vt trn tri t theo thi gian. nh chp t

my bay gip ta v bn mt cch chi tit.

Ngoi ra ta cn raster cn c th c to ra bng cch chuyn i t nhiu ngun

d liu khc nh vector hay TIN.

Hnh 5.14: Hnh chp t my bay.

Hnh 5.15: Bin i t d liu vector sang raster

Cc thnh phn d liu

Raster c to nn bi mt mng 2 chiu cc im nh hay cell. Cell l mt

n v ng nht biu din mt vng xc nh trn tri t. Cc cell u c cng

kch thc. Gc to ca h c t ti cell nm ti nh gc tri. Mi cell c

xc nh bi ch s dng v ch s ct, ng thi n cha mt s nguyn (hoc s

51

thc) biu din kiu hay gi tr thuc tnh xut hin trn bn .

Hnh 5.16: Mng cell v bng thuc tnh.

Kch thc ca cell trong raster ph thuc nhiu vo phn gii d liu.

Cell phi c kch thc nh c th thu thp c chi tit d liu, nhng cng

phi c kch thc ln c th phn tch d liu mt cch thun tin.

Gi tr ca cell s nh ngha cc nhm, lp ti v tr ca cell. Cell ti nhng

im c cng mt gi tr xc nh mt vng, min. Cc cell trong cng mt min

khng cn phi lin kt vi nhau. Khi mt s nguyn c ch nh cho mt tp cc

cell, th s nguyn ny c th l m phn bit gia cc nhm cell. iu ny to nn

mt quan h mt - nhiu gia m v cc cell c cng gi tr. V d cc cell c gi tr

l 400 c gn m l 4, cc cell c gi tr 500 c gn m l 5. M ny c th

xut hin nhiu ln trong raster, nhng ch xut hin mt ln trong bng gi tr

thuc tnh (hnh v). Bng ny lu cc gi tr thuc tnh cho m, iu ny gip vic

cp nht n gin hn. Mt thay i nh ca gi tr thuc tnh s lm thay i cch

th hin ca hng trm i tng trn bn .

Mi cell trong mt raster u c mt gi tr. Gi tr ny biu din mt trong

bn kiu d liu sau:

Nominal (bin tn): mt gi tr thuc kiu d liu nominal s xc nh mt

thc th t mt thc th khc. Nhng gi tr ny c phn loi to thnh cc

nhm. Trong mi nhm, thc th a l s lin kt vi cell ti v tr ca cell .

Nominal c dng trong rt nhiu kiu m nh m s dng t, kiu t trng.

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Ordinal (bin th t): mt gi tr thuc d liu ordinal s xc nh v tr ca

mt thc th so vi cc thc th khc nh thc th c t v tr th nht, th

hai, hoc th ba. Nhng cc gi tr ny khng thit lp t l tng quan gia cc

thc th. Chng ta khng th suy lun c thc th ny ln hn, cao hn hay nng

hn thc th khc bao nhiu

Interval (bin thi gian): mt gi tr thuc d liu interval biu din mt php

o trn mt t l nh thi gian trong ngy. Nhng gi tr ny nm trn mt t l xc

nh v khng lin h vi mt im thc no.

Ratio (bin t l): mt gi tr thuc kiu ratio c th biu din mt php o

trn mt t l vi mt im c nh v mang ngha.

Biu din Point, Line v Polygon trong raster

Trong cu trc d liu raster, point c th c biu din bng mt cell. Line

c biu din bi mt tp cc cell c hng xc nh, rng ca line bng chiu

rng ca mt cell. Polygon c biu din bi mt dy cc cell nm k st nhau.

Hnh 5.17: Biu din cc i tng c s trong Raster.

Mc d ta c th xc nh cc point, line v polygon trong raster mt cch

trc quan, nhng nu ta mun tng tc vi cc i tng ny hiu qu, cch tt

nht l ta chuyn i chng t d liu raster sang d liu vector. S chuyn i ny

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gi l vector ho.

Hnh 5.18: Chuyn i d liu raster sang vector.

Trn hnh v ta thy mt qu trnh chuyn i d liu t raster sang vector.

phn gii ca nh chp s nh hng rt nhiu n chnh xc ca d liu

vector.

Cc u v nhc im ca m hnh raster

u im ln nht ca m hnh raster l ton b d liu hnh thnh bn

c lu trong b nh my tnh. Do vy, cc thao tc kiu nh so snh c thc

hin d dng. Tuy nhin n s gp bt li cho vic biu din ng, im v mi i

tng ny l tp cc cell trong mng. ng thng c th b t on hay rng hn

so vi hnh nh thc.

Kh khn ln nht khi x l d liu raster l vn t bo trn. Th d, ta

c mt bn l vng ven ca mt h nc n l hnh nh bao gm nc v c ven

b. Khi biu din chng trn bn , s gp kh khn trong vic quyt nh gn

tng cell cho lp nc hay lp c. Cc h GIS thng s dng phng php

tho hip: gn thuc tnh sn cho cc t bo thuc loi ny, ngha l chung

khng thuc lp nc v cng khng thuc lp c. Sau ny tu thuc vo ng dng

thc t m xc nh quy lut gn gi tr li cho chng.

Mt vn khc m m hnh gp phi chnh l vic lu tr d liu. Ta

bit rng bn chia ra lm nhiu lp, mi mt lp gm hng triu t bo biu din

mt c trng a l no . Trung bnh mt nh v tinh ph khong 30.000km2 vi

kch thc ca mi im nh l 30m th c khong 35 triu t bo. V th c th ni

rng s lng d liu cn lu tr l khng l, iu ny dn n nhiu kh khn cho

54

h thng thng tin. Vn t ra l cn phi nn d liu nh mt s thut ton thch

hp. Mi thut ton c nhng u im ring: thut ton bo ton d liu cho kh

nng khi phc ton b d liu gc tuy nhin tn v khng gian nh, thut ton ti

u v dung lng lu tr th c th mt mt thng tin so vi lc ban u.

5.1.3 M hnh d liu TIN

Cc ng dng m hnh ho a hnh i hi phng php biu din cao so

vi b mt nc bin. C rt nhiu m hnh biu din b mt thc hin cng vic

ny, trong m hnh li tam gic khng u - gi tt l m hnh TIN c

nh gi l hiu qu nht

Hnh 5.19: Bn vi m hnh d liu TIN.

TIN c kh nng biu din b mt lin tc t nhng tp hp im ri rc. V

mt hnh hc, TIN l tp cc im c ni vi nhau thnh cc tam gic. Cc tam

gic ny hnh thnh nn b mt 3 chiu. Cc im c lu tr cng vi gi tr gc

chiu ca chng. Cc im ny khng cn phi phn b theo mt khun mu no v

mt phn b cng c th thay i cc vng khc nhau. Mt im bt k thuc

vng biu din s nm trn nh, cnh hoc trong mt tam gic ca li tam gic.

Nu mt im khng phi l nh th gi tr hnh chiu ca n c c t php ni

suy tuyn tnh (ca hai im khc nu im ny nm trn cnh hoc ca ba im

nu im ny nm trong tam gic). V th m hnh TIN l m hnh tuyn tnh trong

55

khng gian 3 chiu c th c hnh dung nh s kt ni n gin ca mt tp hp

cc tam gic.

Ta c th lu tr s ca TIN bng danh sch lin kt i hoc cu trc t

phn. C hai phng php ny u m t cu trc hnh hc t p ca bn chia

nh. S m t ny chp nhn tt c cc thao tc duyt cn thit t hiu qu.

Trong m hnh TIN ta c th xy dng m hnh cu trc mng gii quyt cc bi

ton v m t ng, v n l mt trng hp c bit ca bn chia nh.

Hnh 5.20: M hnh cu trc mng TIN.

ng i ny c lu vo khng gian nh trong mi tam gic t, cnh e

v nh v s c mt bn ghi m t c trng ca chng. Bn ghi ca tam gic t c 3

trng con tr. Cc con tr ny tr n cc bn ghi ca cc cnh gn lin vi t. Bn

ghi m t cnh e c 4 trng con tr, trong 2 con tr tr n hai tam gic gn

lin vi n cn hai con tr khc tr n hai nh to nn n. Bn ghi ca nh v c

ba trng lu gi tr, l to x, y v gi tr hnh chiu ca n.

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Cc thnh phn ca TIN

Hnh 5.21: Biu din TIN t trc i tng c bn.

M hnh TIN c th biu din: point, line, polygon.

Breaklines:l cc on thng ni vi nhau m b mt ca a hnh c s thay

i t ngt.

Exclusion area: biu din cc b mt c cng cao.

Project boundary: c th tch b mt ra ngoi mt vng no . Vic ny rt quan

trng trong tnh ton gi tr.

Phng php xy dng TIN t mt tp cc im

Bc 1: thu thp cc im cng vi to x, y, z ca chng bng cc thit b chp,

h thng GPS Thu thp cc ng breakline biu din khu vc m hnh dng b

mt thay i t ngt. Xc nh cc min c cng cao so vi mt nc bin gi

l Exclusion area.

Bc 2: t cc d liu v im v ng trn, phn mm GIS s to ra mt mng

cc tam gic ti u nht, tc l cc tam gic trong mng cng u cng tt.

57

Hnh 5.22: Tam gic trong mng.

Bc 3: mi tam gic ta coi l mt b mt vi dc xc nh.

Hnh 5.23: dc b mt tam gic.

Theo cch xy dng ny, ta c th tnh ton c cao (so vi mt bin) ti

mt im c to x, y bt k bng cch xc nh v tr tam gic u tin sau ni

suy theo chiu cao ca n.

M hnh TIN rt hiu qu trong xy dng b mt. Mt ca im trn b mt t l

vi bin i ca a hnh. Nhng b mt bng phng tng ng vi mt im

thp v nhng a hnh i ni c mt im cao.

Phng php xy dng TIN t cc i tng hnh hc c bn

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Trong phn ny chng ta s tm hiu cch xy dng TIN t point, breakline,

v polygon.

Hnh 5.24: Cc i tng hnh hc c bn trong TIN.

Hin th b mt trong TIN

C nhiu cch m t trc quan b mt trong TIN. Ta c th ng dng TIN

trn bn 2 chiu trong ta dng mu sc th hin: cao, dc, hng.

hin th 3 chiu, ta dng cc phn mm h tr nh ArcInfor ca ESRI. Phn mm

cho php ta nhn cc b mt nhiu gc nhn khc nhau vi cc hnh nh, ng

mc c gp thnh cc np.

5.2. H qun tr c s d liu ca GIS

H qun tr c s d liu l h thng qun l, lu tr, bo tr ton b c s

d liu. H qun tr c s d liu cng cung cp cc cng c cho php ngi dng

hi p, tra cu v tc ng vo c s d liu. C s d liu cho mt h thng GIS

bao gm 2 c s d liu thnh phn chnh l :

* C s d liu a l (khng gian)

* C s d liu thuc tnh (phi khng gian)

59

Trong h thng GIS, h qun tr c s d liu GIS c xy dng bao gm 2

h qun tr c s d liu ring cho tng phn hoc xy dng mt h qun tr c s

d liu chung cho c hai c s d liu con k trn. Thng thng h qun tr c s

d liu GIS c xy dng bao gm 3 h qun tr c s d liu con:

* H qun tr c s d liu cho c s d liu a l.

* H qun tr c s d liu quan h mc tra cu, hi p. H ny c tch hp

cng vi h qun tr c s d liu a l cho php ngi ta dng truy nhp d liu

a l v d liu thuc tnh ng thi. Tuy nhin, h qun tr c s d liu ny cho

thao tc trn c s d liu thuc tnh b hn ch.

* H qun tr c s d liu thuc tnh. Thng thng cc h thng GIS u ly

mt h qun tr c s d liu quan h hin c qun tr v thc hin cc bi ton

trn d liu thuc tnh m khng lin quan n d liu khng gian. V d: FOX, MS

SQL, ORACLE.

V h qun tr c s d liu qun l c s d liu thuc tnh, chng ta

xem xt chi tit trong phn H thng c s d liu. V vy, y chng ta ch i

su vo h qun tr c s d liu cho d liu khng gian.

H qun tr c s d liu cho d liu khng gian bao gm cc h thng con sau:

* H thng nhp bn

* H thng hin th bn

* H thng tra cu, hi p c s d liu

* H thng phn tch a l

* H thng phn tch thng k

* H thng u ra.

60

5.3 Cc thnh phn d liu bn chc nng

Thnh phn quan trng trong h c s d liu GIS l bn . Thng tin a

l c m t khi qut trong cc loi bn a l:

Bn nn

- Bao gm cc bn ng ph, ng quc l, ranh gii hnh chnh, dn c,

sng h, mc bin gii, tn a danh v bn raster.

Bn v d liu thng mi

- bao gm d liu lin quan n dn s, nhn khu, ngi tiu th, dch v thng

mi, bo him sc khe

Bn v d liu mi trng

- bao gm d liu lin quan n mi trng, thi tit , s c mi trng, nh v

tinh.

Bn v d liu tham kho chung

- bn th gii v cc quc gia, d liu lm nn cho cc d liu ring.

Mi loi bn phc v cho mt lnh vc hoc nhiu lnh vc nghin cu

trong h thng GIS, chng u din t chi tit h thng thng tin a l khng gian

thc.

61

Chng 6: CC CNG NGH LIN QUAN

6.1.Thnh lp bn :

6.1.1 Desktop mapping:

L desktop mapping system s dng bn t chc d liu v tng tc

ngi dng. Trng tm ca h thng ny l thnh lp bn : bn l c s d

liu. Phn ln cc h thng Desktop Mapping u hn ch hn so vi GIS v kh

nng qun l d liu, phn tch khng gian v kh nng tu bin. Cc h thng

Desktop mapping hot ng trn cc my tnh bn nh PC, Macintosh, v cc

my trm UNIX nh.

6.1.2 Mapinfo:

MapInfo l phn mm bn ang c s dng rt rng ri trn th trng

Vit Nam. Mt im mnh ca MapInfo l kh nng hin th, gin trang in rt tin

li v y l mt trong nhng u th ca MapInfo so vi cc phn mm GIS khc.

Gii php desktop ca MapInfo tng i nh gn nn MapInfo ang c chim

u th ln Vit Nam, nht l i vi nhng ni tip cn GIS sm, quy m nh.

Ngoi cc gii php desktop, MapInfo cn c cc gii php mng, Web. Tuy nhin

cng nh cc gii php mng v Web ca cc hng khc hin ang t c s dng

trn th trng Vit Nam, v trn thc t th trng ny cng mi lm quen vi

chng.

Nhng c im chnh ca MapInfo gm:

- Chy trn cc h iu hnh: UNIX, Windows.

- H tr cc thit b: Bn s, my qut nh, chut, cc my v.

- Cc chc nng chnh: To vng m, phn tch bn , phn tch mng.

- H qun tr c s d liu: dBase, c s d liu bn trong.

- Cu trc d liu: Non-topological Vector, d liu thuc tnh, d liu bng biu.

62

- n gin, d s dng

- Ph hp vi m hnh quy m nh

- Kh nng to lp bn chuyn mnh v phong ph (hn hn cc phn mm

GIS khc)

- Kh nng gin trang in ,,, v in rt thun li

- Kh nng giao tip vi cc phn mm GIS khc tt

- Cu trc format file m h tr cho vic pht trin cc ng dng chuyn su.

- Kh nng xy dng d liu bn s (kha cnh s ha bn ) yu.

Hin nay c 1 s phin bn mapinfo c s dng kh nhiu c pht trin kh

n nh nh phin bn mapinfo 9.5

6.1.3 ArcGIS desktop:

ArcGIS l dng sn phm h tr trong h thng thng tin a l GIS ca

ESRI. Cc phin bn ban u l ArcInfo, c ci t di dng DOS, ngy nay

cc sn phm ny c pht trin ln nhiu phin bn cao cp hp dng chy trn

nhiu h iu hnh khch nhau nh: Windows, Unix...

ArcGIS c nhiu dng h khc nhau nh:

ArcGIS gm ArcInfo, ArcEdito, ArcCatalog

ArcIMS dng a d liu GIS ln Web

ArcPad dng cho cc thit b Mobile

ArcSDE dng lm cu ni truy xut vo cc h qun tr c s d liu

ArcExplore dng truy cp ngun d liu trn Web

ArcGIS server h tr cc chc nng bn pha server cng nh trin khai cc

ng dng qua mng.

ArcGIS h tr nhiu phn m rng gi l cc Extension, mi Extension h tr

mt s chc nng chuyn bit nh: phn tch khng gian (spatial analyst), phn tch

63

3D (3D analyst), phn tch mng (Network analyst), x l d liu, thng k khng

gian...

ArcGIS h tr c c nhiu nh dng d liu khc nhau (khong 300 nh

dng) nh shapefile, geodatabase, AutoCad, Raster, Coverage,...

Ngy nay ArcGIS c s dng rng ri trong cc ng dng trong H thng

thng tin a l nh qun l Mi trng, t ai, X hi, Kinh t...

Dng phn mm ArcGIS du nhp vo Vit Nam t nhng nm 90, sau cc

phn mm GIS khc nh MapInfo hay Geomedia. Tuy nhin, do tnh nng mnh

m v nhiu cng c h tr nn ArcGIS c bt u s dng nhiu Vit Nam,

c bit vi cc h thng GIS ln.

6.2.CAD ( tr gip thit k nh my tnh )

H thng CAD tr gip cho vic to ra cc bn thit k xy dng nh v c

s h tng. Tnh nng ny i hi cc thnh phn ca nhng c trng c nh c

tp hp to nn ton b cu trc. CAD yu cu mt s quy tc v vic tp hp

cc thnh phn v cc kh nng phn tch rt gii hn. H thng CAD c th c

m rng h tr bn nhng thng thng b gii hn trong qun l v phn

tch cc c s d liu a l ln.

6.3.Vin thm v GPS ( h thng nh v ton cu)

Vin thm l ngnh khoa hc nghin cu b mt tri t s dng k thut

cm bin nh quay camera t my bay, cc trm thu GPS hoc cc thit b khc.

Cc thit b cm bin ny thu thp d liu dng nh v cung cp cc kh nng thao

tc, phn tch v m phng nhng nh ny. Do thiu cc tnh nng phn tch v

qun l d liu a l, nn khng th gi l GIS thc s.

H thng nh v ton cu (ting Anh: Global Positioning System - GPS) l

h thng xc nh v tr da trn v tr ca cc v tinh nhn to. Trong cng mt thi

64

im, mt v tr trn mt t nu xc nh c khong cch n ba v tinh (ti

thiu) th s tnh c ta ca v tr .

GPS c thit k v qun l bi B Quc phng Hoa K, nhng chnh ph

Hoa K cho php mi ngi trn th gii s dng n min ph, bt k quc tch

no.

6.4. DBMS ( h qun tr c s d liu):

H qun tr c s d liu chuyn v lu tr v qun l tt c cc dng d liu

bao gm c d liu a l. Nhiu h GIS s dng DBMS vi mc ch lu tr d

liu. DBMS khng c cc cng c phn tch v m phng nh GIS.

6.5. Internet v network computer ( mng my tnh v truyn thng).

Trong thi bui hin i ha, cng ngh my tnh v truyn thng tr nn

cc k gip ch cho cc d n, cc ngnh , vic a GIS vo cng ngh my tnh v

truyn thng l mt bc tin mi. Da vo internet, GIS c pht trin mnh m

v lan rng khp. Trong vic tip cn hng i tng, GIS ang c bc tin t

cch tip cn c s d liu sang hng tri thc nh internet.

C th ni trong GIS H c s d liu a l l ci hn, cn h thng thng

tin v mng my tnh truyn thng l th xc. Internet gip GIS cao hn, xa hn,

su hn trong cc lnh vc i sng v cng ngh .

65

Chng7: CC BI TON NG DNG GIS

7.1.Cc lnh vc dng chung, chia s k thut v cung cp d liu cho GIS.

7.1.1 Trc a:

Trc a l khoa hc v o c v xc nh v tr ca cc i tng trn mt

tri t. Trong thit k ng, m hnh DEM c s dng rt nhiu: tnh khi

lng, hin th 3 chiu. Cc pht trin mi trong cng ngh:

* Thit b o c my o in t total station

* H thng nh v ton cu GPS (Global Positioning System)

* Lin kt trc tip gia thit b trc a v c s d liu khng gian.

* c im trong lnh vc ny:

* T l ln, o c vi s chnh xc n mm phn gii trong m hnh DEM cao

* M hnh d liu dng loi vector.

7.1.2 Bn :

Mt h thng GIS lin quan trc tip n bn a l, hn th bn l

yu t quan trng nht trong h c s d liu trong GIS.

7.1.3 Vin Thm:

y l lnh vc cung cp d liu cho GIS. Vin thm cho php thu thp

thng tin v tri t t v tinh hay my bay.

Hai nguyn tc chnh ca vin thm dng vi GIS:

* Cht lng v gi tr d liu c ci thin qua chnh xc ca php phn loi.

* c y thng tin cho to quyt nh, cn kt hp vi cc lp thng tin khc

khng gian quan st c t ngoi khng gian. V d: ranh gii hnh chnh.

66

+) c im ng dng trong lnh vc ny:

- T l bao trm nhiu t l ph thuc vo cao bay chp v kh nng thit

b

- M hnh d liu thu thp ch yu dng raster

- nh sau khi phn loi c th chuyn sang dng vector hoc input vo GIS

Vin thm giao tip vi GIS nh l mt hng ang c pht trin hin nay. C

hai lnh vc u ang c pht trin.

Trong vin thm, cc h thng bao gm cc chc nng x l nh.Giao tip l

khng kh khn v mt k thut, tuy nhin vn cn c s khng tng thch v m

hnh d liu, format chun v phn gii khng gian.

Nhiu phn mm GIS c chc nng chuyn i d liu t cc h thng vin

thm v hin th d liu vector trn nn nh vin thm

Bn nh: nh c nn chnh, a cc yu t ton hc v bn ln: php

chiu, to , im khng ch, khung, li..v..v..

7.2.Cc ng dng p dng cng ngh GIS nh l mt cng c qun l , phn

tch d liu v tr gip to quyt nh.

7.2.1 Qun l v iu tra ti nguyn:

7.2.1.1 Qun l ti nguyn thin nhin TI NGUYN NC

GIS c th h tr nh gi mc nc ngm, m phng h thng sng h v

nhiu ng dng lin quan n qun l ti nguyn nc khc. Nhng v d di y

l mt vi ng dng ca GIS trong lnh vc ny.

67

Kim sot mc nc ngm

Hnh 7.1: bn kim sot mc nc ngm.

Duy tr mc nc ngm thch hp trong cc vng khai khong l mt vn

ln. Trng i hc K thut Aachen, c s dng GIS kim sot mc nc

ngm cho cc vng khai thc than, to cc bn mc nc ngm, kt hp vi cc

d liu khc nh th nhng, a hnh, quy m khai thc m, cng ngh k thut

c s dng, cung cp cng c c lc cho cc nh phn tch.

Kim sot s phc hi mc nc ngm

Hnh 7.2: Kim sot v phc hi mc nc ngm.

nh gi s phc hi mc nc ngm l rt kh khn, nhng vi cng ngh

GIS cng vic ny tr nn d dng hn. Umlandverband Frankfurt, c, dng

GIS xy dng cc lp bn cho mi tnh ton v s phc hi mc nc ngm.

68

Nhng lp ny sau c kt hp li to nn mt bn cui cng biu din

s phc hi ca mi vng.

GIS gip cho cc nh nghin cu d dng tnh ton v m phng ng thi

tc phc hi mc nc ngm ca cc vng khc nhau.

Phn tch h thng sng ngi

Hnh 7.3: Phn tch h thng song ngi.

Vin a cht Zagreb, Croatia, s dng GIS phn tch h thng sng

cng nh ton b vng lu vc sng Drava. Vi cng ngh GIS c th xy dng

m phng mng li sng ngi ca khu vc cng cc thng s c trng cho mi

dng chy v phn tch nhng nh hng m chng c th chu tc ng.

Qun l cc lu vc sng

Hnh 7.4: Qun l cc lu vc sng.

69

Lu vc sng l mt h thng nhy cm v phc tp. Qun l lu vc sng

i hi lu lng nc y , duy tr s n nh ca cc h sinh thi, kim sot l.

Cng ty Qun l Cht thi v Nng lng Ht nhn Thu in v Nespak, Pakistan

phi hp s dng GIS h tr qun l vng lu vc sng Torrent Pakistan. GIS

c s dng m hnh ho s cn bng nc, qu trnh xi mn, v kim sot l

cho khu vc.

Hammon, Jensen, Wallen & Associates dng GIS kim sot vng lu vc

sng Santa Lucia Preserve. M hnh khng gian ba chiu c xy dng nh cng

ngh GIS, gip cc nh nghin cu tip cn chnh xc v a hnh v th nhng

ca khu vc, t xy dng nhng quy lut din bin quan trng cho ton b vng

lu vc sng.

Kim sot cc ngun nc

Hnh 7.5: Kim sot cc ngun nc.

Ti M, GIS c dng qun l s phn b ca cc ngun nc, nh

cc nh khoa hc c th d d xc nh v tr cc ngun nc ny trong ton b h

thng.

Qui hoch s dng ti nguyn t

Cng ngh GIS h tr rt nhiu trong cng vic quy hoch s dng t.

Nhng d liu v hin trng s dng t c thu thp t nhng quan trc khng

gian c x l trong h GIS, lp bn hin trng, km l nhng s liu phn

70

tch. Da vo cc nh qui hoch c th d dng qun l v pht trin cc k

hoch s dng t hp l.

Thnh ph Brno, Cng ho Czech, dng cng ngh GIS pht trin qui

hoch tng th ca thnh ph v hin th thng tin theo c s d liu GIS a chnh

ca thnh ph.

Hnh 7.6: TP Brno.

Mlada, Cng ho Czech cng s dng GIS h tr k hoch quy hoch li

mt khu sn bi qun s, nh gi v m phng cc loi ti nguyn t: t nng

nghip, t nng nghip, t t nhin.

Hnh 7.7: M phng ti nguyn t.

Vin a l "Agustin Codazzi" (IGAC) ca Colombia dng cng ngh

GIS hin th v kim sot hin trng s dng t hin nay v trong tng lai ca

thnh ph Ibague.

Phn tch xu hng xy dng

S Pht trin Nh v th Adelaide, Australia s dng GIS phn tch xu

hng xy dng ca thnh ph, t ch ra s m rng ca thnh ph v nh

hng ca n i vi c s h tng.

71

Hnh 7.8: Phn tch xu hng xy dng.

Kim sot ti nguyn t

7.9: Ti nguyn t.

Cc d n pht trin c xut dc theo bin gii Mexico v M c h

tr bi cc thng tin ca GIS, chng hn kim k, lp bn cc ngun ti

nguyn, ch thu vn, tc ng ca con ngi, c s h tng dc theo bin

gii.

7.2.2 GIS vi mi trng: Cc ng dng GIS c lin tc pht trin trong lnh vc qun l v bo v

mi trng. T chng trnh kim k ngun ti nguyn thin nhin ca Canada

trong nhng nm 1960, n cc chng trnh GIS cp bang ca M bt u vo

cui nhng nm 1970, n m hnh ho qun l cc s c mi trng hin ang

c pht trin, cng ngh GIS cung cp cc phng tin qun l v phn

tch cc yu t nh hng n mi trng ngy cng hu hiu hn.

72

Xu hng hin nay trong qun l mi trng l s dng ti a kh nng cho php

ca GIS. S pht trin ca phn cng lm cho my tnh c nhiu kh nng hn,

mnh hn v cc ng dng GIS cng tr nn thn thin hn vi ngi s dng bi

cc kh nng hin th d liu ba chiu, cc cng c phn tch khng gian v giao

din tu bin.

Nh kh nng x l cc tp hp d liu ln t cc c s d liu phc tp,

nn GIS thch hp vi cc nhim v qun l mi trng. Cc m hnh phc tp

cng c th d dng cp nht thng tin nh s dng GIS.

GIS c s dng cung cp thng tin nhanh hn v hiu qu hn cho cc nh

hoch nh chnh sch. Cc c quan chnh ph dng GIS trong qun l cc ngun

ti nguyn thin nhin, trong cc hot ng quy hoch, m hnh ho v quan trc.

GIS cng c s dng nh gi cc s c mi trng. Cc c quan chnh

ph v a phng phi i ph nhanh chng vi thin tai, cc ri ro trong cng

nghip v cc s c mi trng. Thng tin a l l nhng thng tin quan trng

a ra nhng quyt nh mt cch nhanh chng. Cc phn tch GIS ph thuc vo

cht lng, gi tr v tnh tng thch ca cc d liu a l dng s.

Vic chia x d liu s kch thch s pht trin cc nhu cu v sn phm v dch v

GIS. Cc ngun d liu tng thm nh s kt hp ca GIS vi GPS (h thng nh

v ton cu) v cng ngh vin thm, cung cp cc cng c thu thp d liu hiu

qu hn.

7.2.3 Hot ng v nghin cu khoa hc trong cc trng i hc v vin nghin cu:

Trong nhng nm qua, vic nghin cu, o to v ng dng GIS c

trin khai rng khp trn c nc. khu vc duyn hi min Trung v Ty Nguyn,

GIS c ng dng tng i rng ri cc trng i hc v cc c quan

chuyn mn thuc nhiu lnh vc khc nhau. Thi gian qua, Khoa a l - a cht

ni ring v Trng i hc Khoa hc ni chung cng c nhiu nghin cu ng

dng GIS trong nghin cu khoa hc v ging dy.

73

Trong thi gian gn y c rt nhiu hi tho v GIS c t chc ti cc trng

i hc , vi s tham gia ca cc b ging vin ca 1 s trng i hc, cc vin v

cc trung tm nghin cu.

74

Chng 8: PHT TRIN GIS TRONG NG DNG TNG

LAI.

8.1 GIS trn Internet ( ArcGIS Server )

ArcGIS Server l nn tng xy dng h

thng thng tin a l (GIS) c quy m ln,

trong cc ng dng GIS c qun l tp

trung, h tr a ngi dng, tch hp nhiu

chc nng GIS mnh v c xy dng da

trn cc tiu chun cng nghip. ArcGIS Server

qun l cc ngun d liu a l nh bn , s

liu khng gian

y l mt h thng phn phi gm nhiu thnh phn c th trin khai trn

nhiu my khc nhau. Mi thnh phn ny nm gi mt vai tr c th trong qu

trnh qun l, hot ng hoc ngng hot ng, cn bng ngun ti nguyn cung

cp cho mt hay nhiu server. Cc thnh phn ca ArcGIS Server bao gm:

My ch GIS (GIS Server): Lu tr v chy cc ng dng server. My ch

GIS bao gm mt my ch SOM (Server Object Manager) v mt hoc nhiu my

ch SOC khc (Server Object Containers)

My ch Web (Web Server): Lu tr cc ng dng v dch v Web c s

dng cc thnh phn chy trn my ch GIS.

Trnh duyt Web: c dng kt ni n cc ng dng Web chy trn

my ch Web.

75

Cc ng dng Desktop: Kt ni theo giao thc truyn dn siu vn bn

(HTTP) n cc dch v Web chy trn my ch Web hoc kt ni trc tip n

my ch GIS thng qua mi trng mng LAN hay WAN

Nhng c im chnh ca ArcGIS Server.

8.2 Khung GIS chun.

ArcGIS Server cung cp mt framework chun dng cho vic pht trin cc

ng dng trn my ch GIS. B phn mm GIS ph bin nht hin nay (ArcView

, ArcEditorTM, ArcInfo) cng c xy dng da trn cng mt nn tng.

ArcGIS Server khng nhng c th m rng ra m cn cung cp rt nhiu chc

nng mnh cho php cc lp trnh vin khng phi mt nhiu thi gian nghin cu,

xy dng cc chc nng GIS t u.

8.3 Chi ph thp.

ArcGIS Server c kh nng h tr cc ng dng ln nh xy dng Web GIS,

chy trn nhiu my ch, h tr a ngi dng. Cng ngh ADF khng gii hn

bn quyn. iu ny cho php cc ng dng server c th chy trn nhiu my ch

Web, do lm gim gi thnh, ch ph thuc vo s lng ngi dng.

8.4 Cc ng dng web.

ArcGIS Server cung cp mt b cc Web controls. Cc Web controls ny

lm n gin i cc cng on xy dng tch hp bn vo cc ng dng Web,

gip cho cc lp trnh vin tp trung vo xy dng cc chc nng GIS theo mc

ch ca mnh.

8.5 Cc mu ng dng web.

ArcGIS Server cung cp kh nhiu mu ng dng Web. Lp trnh vin c

th s dng nhng mu ny kt hp vi cc Web controls to ra cc ng dng

Web theo mc ch ca mnh hoc cng c th dng tham kho.

76

8.6 H tr a min.

ArcGIS Server ADF dnh cho Java chy trn nhiu h iu hnh s dng

kin trc ca UNIX v h tr mt s lng ln cc Web server.

Bn thn GIS Server c h tr cho Windows, Sun Solaris v Red Hat Linux.

ADF dnh cho .NET ch chy c trn mt s h iu hnh Windows. Tham kho

ti http://support.esri.com bit thm thng tin v nhng h iu hnh no c

h tr.

8.7 H tr nhiu ngn ng lp trnh.

ArcGIS Server h tr nhiu ngn ng lp trnh, bao gm c .NET v Java

pht trin cc ng dng, dch v Web. S dng COM v .NET cho php m rng

ArcGIS Server cc tnh nng theo yu cu ring, ngoi ra COM, .NET, Java, v

C++ cn c dng xy dng cc ng dng Desktop client. iu ny cho php

cc i tng c lp trnh bng nhiu cng c v cc lp trnh vin khng nht

thit phi bit nhiu ngn ng lp trnh.

8.8 Cc phn m rng ca Arc GIS server.

B cng c cho lp trnh vin s dng ArcGIS Server cn km theo cc chc

nng m rng ca ArcGIS 3D AnalystTM, ArcGIS Spatial Analyst v ArcGIS

StreetMapTM.

8.9 Cung cp nhiu ti nguyn cho cc lp trnh vin.

B cng c pht trin ArcGIS Server cung cp mt h thng tr gip da

theo cc s m hnh i tng (OMDs), cc mu ng dng Web v c cc on

m lp trnh mu gip cho cc lp trnh vin d dng tip cn, s dng.

Ti sao s dng ArcGIS Server

ArcGIS Server cho php cc lp trnh vin v cc nh thit k h thng trin

khai qun l tp trung GIS. iu ny s lm gim bt gi thnh cho nhng ngi s

dng GIS v c th m rng kh nng h tr ngi dng, tit kim gi thnh ci t

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phn mm trn tng my. Cng vi kh nng h tr vi cc dch v Web, ArcGIS

Server c th tch hp l tng vi cc h thng thng tin khc nh cc c s d

liu quan h, cc my ch Web, v cc my ch ln.

ArcGIS Server c b sung thm vo gia nh sn phm cc ng dng chy

trn server ca ESRI l ArcIMS, ArcSDE, v ArcGIS Server. ArcIMS cho php

xut bn cc bn v metadata da trn nn Web rt tt, ArcGIS Server qun l

tp trung cc ng dng GIS cao cp. ArcSDE qun l truy cp d liu dnh cho

ArcGIS Server v ArcIMS

Nhng ai s dng ArcGIS Server?

Nhm s dng cc ng dng Web: Nhm ngi ny ch cn c trnh duyt

Web l c th kt ni v tng tc vi cc dch v, ng dng Web GIS m khng

i hi phi bit v GIS.

Nhm pht trin cc ng dng v dch v Web : S dng ADF xy dng

cc ng dng v dch v Web da trn nn .NET hoc Java. Xy dng cc ng

dng Web dnh cho ngi dng ArcGIS Desktop kt ni n qua mng Internet,

tch hp cc chc nng ca GIS v c th c s dng trong cc chng trnh

khc.

Nhm s dng cc sn phm ArcGIS Desktop : Nhm ngi ny c th dng

cc phn mm ArcMap hay ArcCatalog kt ni v ti d liu t my ch qua mng

LAN hay Internet. Thit k v xy dng d liu cho cc ng dng ca ArcGIS

Server.

Nhm pht trin ArcGIS Desktop, ArcGIS Engine : Nhm ngi ny c th

pht trin cc ng dng c kh nng kt ni n GIS server v chy cc thnh phn

ArcObject trn server. Cho php tch hp cc chc nng trn desktop vi cc chc

nng trn server.

78

Nhm qun l server: Nhm ny s dng ArcCatalog kt ni n my ch

qua mng ni b, qun l server cng nh cc ng dng chy trn server, thm hoc

g b cc my con vo h thng, phn quyn truy cp v s dng d liu

79

Chng 9: KT LUN

Vi mong mun tm hiu v cng ngh, k thut mi , c s quan tm v

hng dn ca Thy ng Nhn Cch, chng em hon thnh ti: tm hiu v

h thng thng tin a l GIS .

Sau khi thc hin ti, chng em t c mt s kt qu sau:

o Tm hiu c v h thng thng tin a l GIS, mt h thng thng tin ang pht trin rt mnh trn th gii v ngay ti Vit Nam v c tm ng

dng rng ri hin nay trong cc lnh vc qun ly mi trng v bn

a cht Cng nh bit thm v mt s h thng khc nh GPS h

thng nh v ton cu.

o Chng em cng bit thm v mt s phn mm ng dng lin quan n k thut v cng ngh GIS nh ArcGIS, mapinfo, JVNmobile GIS

o minh ha cho vic s dng h thng thng tin GIS v cng ngh GIS-mobile, chng em xy dng mt ng dng tm kim bn trn in

thoi vi phn mm JVNMobileGIS do Vit Nam pht trin , chy trn

h iu hnh mobile Symbian . Ngoi ra c s dng n chng trnh gi

lp in thoi trn PC l S60_3rd_MIDP_FP1 ca nh cung cp

Microsoft.

Mc d c gng ht sc nhng do thi gian c hn v vic tm hiu cng

ngh mi c nhiu kh khn do khng c nhiu ti liu , ch yu tm trn internet.

V vy ng dng ca chng em ch mang tnh minh ha cho vic s dng cng ngh

m thi!

80

TI LIU THAM KHO [1] http://www.ebook.edu.vn/

[2] http://www.gis.com

[3] http://www.vnthuquan.net

[4] http://www.vi.wikipedia.org

[5] http://www.gis-home.net/

[6] http://vi.cosmotopic.com/r/giao-trinh-gis

[7] http://sites.google.com/site/mystusvittatus2/gis_nguon_mo

[8] http://thuvien.maivoo.com/Khoa-hoc-c9/GIS-va-moi-truong-DU-LIEU-CHO-

GIS-d34875

[9]http://khcn.mt.gov.vn/?Param=category&catid=37&subcatid=49&ArticleId=102

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