Hệ thống thôn tin đại lý gis

•**« TS DANG VAN DLTC HE THONG THONG TIN t>!H LY NHA XUAT BAN KHOA HOC VA KY THUAT Ha Noi - 2001 Chiu trach nhiem xuat ban: Bien tap: Ve bia: PGS, TS TO DANG HAI NGUYEN KIM ANH HUONG LAN 6.6 T 7.3 978 - -0 K H K T-2001 In 1.000 cudn, kh6 16 x 24cm, tai XI nghiSp in 19 - s6 during NguySn Phong Sac - Nghia Tan - C lu Gi^y - Ha N6i Giay phep xuat ban s6': 978 - 30, ngky 20 thang nam 2001 In xong va n6p luu chilu thang nam 2001 loi n o i o a u H tr — Loai ngucri ludn luPn mong muPn hieu ro cac hidn tupng tu nhien va Trai dat de chinh phuc chting D6 dat dupe muc dfch nay, thong thuemg ngucri thuc hidn mpt loat cac c6ng vide nhu sau: (a) thu thap du lieu cua Trai dat va hien tupng tu nhien; (b) nhrip du lieu vao may tfnh de quan ly hieu qua; (c) phrin tfch du lieu d l tim qui lurit va cac thong tin trp giup quyet dinh; (d) tac dpng trer lai cac hi6n tupng tu nhi6n va the' gidri thuc Con ngucri da thuc hien co hieu qua cac c6ng vide tren nhd cac he thP'ng tin hoc Do hriu het du lieu dupe thu thrip va xu ly lien quan de'n vi trf tren Trai dat, cho ndn he thong th6ng tin dia ly (Geographical Information System - GIS) tref c6ng cu phu hpp nha't Tuy rang GIS da dupe nghien cUu va phat tridn ttir nhieu nam nay, nhemg cho de'n cac may vi tfnh co t6'c d6 xer ly cao, kha nang ltm tru khoi du lieu 1cm va kha nang hie’n thi d6 hoa nhanh thi no mod dupe phd bie'n rpng rai Ngay nhieu ngucri vin cho rang ting dung edng nghe GIS va dac biet thie't ke' phrin mem GIS la vide lam kho khan De ting dung de dang va co hidu qua loai cPng nghd mod me doi hoi ngucri sir dung phai quen vod cac khai nidm co ban, dac bidt cac van dd vd xer ly khong gian, thupc llnh vuc GIS Vdd mong muon lam giam bort kho khan vide sti dung hay phat trien hd thdng GIS, tai lidu trade hd't gitip ngucri doc hidu dupe cac nguydn ly, ky thuat m6 ta, xer ly va hidn thi dfi lidu khPng gian va du lidu thupc tfnh GIS, sau gitip cac ky su tin hoc c6 kha nang xay dung cac hd thPng GIS chuydn dung, phu hpp vdd muc tidu cu the Quydn sach co the huu fch cho nhung hoat dpng llnh vuc cong nghd phan mdm va la tai lidu tham khao tPt cho cac sinh vidn va hoc vidn cao hoc Quyen sach bao g6m bay chuong vdi ca'u true nhu sau: Chuong gid(i thieu t6ng quan vd GIS de giup ngudi doc hieu nhanh tong the vd no Chuong trinh bay cac khai niem co ban, dinh nghia, nhiem vu, phSn va cac thao tac cua GIS Chuong dd cap den m6 hinh da lidu khdng gian, each thde bieu didn doi tuqng khdng gian may tmh cho nguoi sir dung co kha nang quan ly duqc khd'i luqng du lidu phire tap, khdng 16 cua the gidi thuc Chuong tap trung trinh bay ve he thong toa dia ly va phuong phap bieu didn dd'i tuqng tren bd mat Trai da't lam co so luu trtr du lieu hinh hoc co scf du lidu (CSDL) dia ly Chuong m6 ta cac phuong phap thu thap va s6 hoa du lidu khdng gian Sau la trinh bay cac thuat toan xur ly du lidu thd giup hd GIS hoat ddng co hidu qua Phan CSDL dia ly duqc trinh bay chuong Cach thde luu tru du lidu dia ly tdp va cac md hinh va kidn true CSDL hd GIS duqc xem xet Chuong bao gdm mdt sd thuat toan co ban duqc sir dung de xay dung cac chuc nang phan tlch du lidu khdng gian hd GIS Tidp theo la md ta cac phuong phap bieu didn ban d6 thong kd cho dd hieu, phu hop vdi nhu cau cua ngudi sir dung Chuong lidn quan dd'n va'n dd tich hop GIS va Web Cac md hinh tmh toan va Internet, cac giai phap xay dung he GIS trdn co sd Web duqc trinh bay Quydn sach duqc hinh tfir nhung kinh nghidm cua tac gia da nhidu nam hoat ddng linh vuc GIS, da tham gia xay dung nhidu hd GIS chuydn dung, ting dung va ngoai nude, da tham gia giang day chu dd cho mdt sd trudng dai hoc Trong qua trinh bien soan tac gia da nhan duqc nhidu y kidn gop y quf bau cua cac chuydn gia nhidu linh vuc lidn quan Trudc hd't tac gia xin chan cam on ThS Dang Van Luyd'n (Khoa Dia chat Dai hoc Khoa hoc Tu nhidn), TS Dd Trung Tua'n (Vien Dao tao Cdng nghe ThOng tin - Dai hoc Qud'c gia Ha n6i), PGS, TS Nguyen Van Tam (Vien C6ng nghe Th6ng tin - Trung tam Khoa hoc Tu nhien va Cdng nghe Qud'c gia) va cac d6ng nghiep khac c6ng tac tai Vien C6ng nghe Th6ng tin da doc va cho y kie'n svra chua ban thao Muc du da rat c6 gang nhung tai lieu kh6ng tranh khoi cac sai sot Tac gia xin cam on moi y kie'n dong gop cua ban doc Dia chi lien lac: Phdng GIS, Vien Cong nghe Thong tin, Trung tam Khoa hoc Tu nhien va Cong nghe Qud'c gia Email: dvduc(3)ioit.ncst.ac.vn Ha N6i, thang 02 nam 2001 t Ac GIA M U C IV C u & m Oi b m I u t s i h u A t n g G v \ € t t At C t a ^ L T ^ N G QUAN v £ H$ THONG TIN DIA l_V 11 L lG E & g > ? ~ 13 1.L I D§nh ngtua G IS 13 l A l & c f M i vuc khoa hoc c6ng nghe lien quan de'n GIS 18 1.3 Ctic Knh vuc ting dung G IS 19 1.1.4 Chi phi cho GIS 21 1.2 Cac td cua he thdng tin dia ly 21 1.2.1 Con nguci 22 1.2.2 DuTieu 24 1.2.3 C6ng cu phSn m6m 26 1.2.4 Giao dien ngucti dung 27 1.2.5 Phdn cting 27 1.3 Tdng quan cac chtic nSng cua he th6ng tin dia ly 28 1.3.1 Thu thtip dfi litiu 30 1.3.2 Xvr ly du: lieu th 31 1.3.3 Luu tru va truy cap du lieu 35 1.3.4 Tim kie'm va phan rich kh6ng gian .37 Chuong MO HINH VA CAU TROC DO l_l£u KH6NG GIAN 49 2.1 Cac khai niem co sd .49 2.2 M6 hinh thting tin kh6ng g ian 51 2.3 Md hinh du lieu raster 55 2.3.1 Truong raster don gian 55 2.3.2 Ca'u trtic dtf lieu raster 59 2.4 M6 hinh dti lieu vecto 66 2.4.1 Cdu trtic dti lieu toan da giac 69 2.4.2 Ca'u trtic cung-ntit 69 2.5 Md hinh dir lieu ludti tam giac khdng ddu (TEN) 72 2.5.1 Phuong phap Voronoi 72 2.5.2 Ca'u true dd lieu T IN 76 2.6 So sanh mo hinh raster va m6 hinh vector .81 am ong H£ THONG THAM CHIEU KH6NG GIAN 83 3.1 Hinh dang Trai da't 84 3.1.1 Trai da't phang 84 3.1.2 Trai da't hinh clu va hinh elip trdn xoay 85 3.2 Toa dd vudng phang 90 3.3 Toa dia cau 94 3.4 Phep chie'u ban d 98 3.4.1 Phan loai cac lop phep chieu 99 3.4.2 Lira chon phep chie'u cho ling dung 114 3.4.3 Khai niem ty le ban d6 116 am ong THU THAP VA TI^N X ft L t DUT LIEU BjA L ? .119 4.1 T6ng quan v i thu thap du: lieu dia ly 119 4.2 Cac phuong phap nhap du lieu dia ly 122 4.2.1 Trac dac mat dat 123 4.2.2 Do dac bang ve tin h 124 4.2.3 Quang trac .* 126 4.2.4 Vien tham 128 4.3 Nhap dd lieu td ban d6 gia'y 131 4.3.1 Tim kie'm ban d6 phu hop 131 4.3.2 SO'hoa ban d6 132 4.4 Bie'n d6i anh ban d6 vecto sang raster va nguqc la i 140 4.4.1 Bie'n d6i vecto sang raster 141 4.4.2 Bie'n ddi raster sang vecto 146 4.5 Tidn xd ly dd lieu ban dd vecto 149 4.5.1 Nan chinh hinh hoc va qui chie'u dia ly 149 4.5.2 Khai quat hoa ban d d rvSl57 Chuong CO s DO LI$U THONG TIN DIA L ? .H 169 5.1 Ca'u true tep co sd 169 5.1.1 Cac dern vi thdng tin ltru tru — 169 5.1.2 T6 chirc tep 172 5.2 Khai quat he quan tri co sd dir lieu 177 5.2.1 Y6u eSu he quan tri co sd dir lieu ; 178 5.2.2 Cac phan cua he quan trico sd dir lieu 180 5.2.3 Md hinh khai ni6m 182 5.2.4 M6 hinh ngtf nghia 185 5.2.5 Md hinh ld g ic 188 5.2.6 Md hinh quan h e 189 5.3 ting dung co sd du lieu GIS .197 5.4 Khudn mSu tep du lieu vecto 202 Chuong PHAN T1CH VA HIEN TH( D ti LIEU DIA L t 205 6.1 Xur ly du lieu khong g ia n 205 6.1.1 Cac thao tac co ban vdi dudng va di^m 205 6.1.2 Cac thao tac vdi da g iac 212 6.1.3 N6i suy 221 6.2 Bi£u dien ban d6 the'ng k e 224• 6.2.1 Du lieu th6'ng ke 224 6.2.2 Cac phuong phap lap ban d 228 Chuong H£ THONG TIN D|A L? VA INTERNET 244 7.1 So luqc v i Internet .244 7.1.1 Cac m6 hinh tfnh toan 244 7.L2 Mang may tfnh Internet 249 7.1.4 Giao thurc truyln tin TCP/IP 250 7.1.5 Dichvu W W W .252 7.2 Ke't n6i CSDL dia ly va Web 259 7.2.1 Cac giai phap 260 7.2.2 Cac loai ung dung thong tin dialy true tuyen 263 7.2.3 Lua chon giai phap 267 TAI U f U THAM KHAo 271 ^ MOT S THUAT NGUT VIET TAT 3D AM/FM ANSI ASP B-tree CAD CGI CGM CORBA DBMS DCOM DCW DEM DGN DGPS DIME DLG DNS DWG DXF E-R ESRI FTP GIF GIS GLONASS GPS HTML Tree Dimensions Automated Mapping/Facilities management American National Standards Institute Active Server Pages Balanced Dynamic Tree Computer-Added Design Common Gateway Interface Computer Graphics Metafile Common Object Request Broker Architecture Database Management System Distributed Component Object Digital Chart of the World Digital Elevation Model MicroStation Design Files Differential Global Positioning System Dual Independent Map Encoding Digital Line Graph Domain Name Service AutoCAD Drawing Files Drawing Exchange Format Entity-Relationship Environmental Systems Research Institute File Transfer Protocol Graphics Interchange Format Geographic Information Systems Geographical Information Systems Geographic Information Science Global Navigation Satellite System Global Positioning System HyperText Markup Language Chifdng He thong tin dja ly va Internet 259 (hinh 7.12) M6i ASP la tep c6 ten voi phan m a rong la ASP va chua ea cu phap HTML Va mo ta logic phia may chu (VBScript thuPng dupe sir dung cho muc dfch nay) Khi dich vu Web nhan dupe yeu cSu HTTP til tai lieu ASP thi tep tra lai HTML tuang ung dupe phat sinh Sue manh cua ASP la cho kha nang de dang tuong tac voi cac doi tupng khac nhu cac doi tupng xam nhap CSDL, tac nghiep khach/chu da tfeg Hinh 7.11 ISAP1 Hinh 7.12 ASP 7.2 KET N l CSDL D|A LY V A WEB Khi Internet dupe su dung rpng rai tren toan cau (1995) thi da co nhieu du an x&y dung cac he thong GIS co tlnh hi6u qua cao nhb chia se cac thong tin khong gian tren mang Internet Cac he thong tin cho phep to chuc luu tru, khai 260 H i THONG T H 6N G TIN P jA L * thac thdng tin dia ly thOng qua mang Internet duqc goi la he thong tin dia ly phan tan hay he thong tin dia ly true tuyen 7.2.1 Cac giai phap Cac ung dung cua he thong tin dia ly true tuye'n co th i don gian la ban d6 ve trade cac trang Web cho de'n he thing phuc tap lien ket mang vdi he thing GIS d i ngucri dung ttr xa chia se du lieu chung "trong thdi gian thuc" Cac ung dung GIS true tuyen thing thudng bao gim server (de’ luu du lieu va ung dung), client (de’ sii dung dii lieu va ling dung) va mang th6ng tin (d! dilu khie’n luing thing tin giura client va server) Khi he thing GIS true tuyen hoat ding, m it loat cac cing viec se duqc thuc hien, bao g im xir ly caqyeu clu, thuc hien txm kiem, phan tich dia ly, phat sinh cac bao cao va lien tuc hien thi ban d6 Nhiim vu ddu tien cua cing viec thie't ke' he thing GIS true tuye'n la xac dinh loai cing viec danh cho server va client Cac cing viec co the duqc phan chia nhu tren bang 7.1 cho server va client [BRAN97] cua he thong Bang 7.1 Phan bo edng viqc tren h# thong khach/chu N h e clien t NhiSm vu c£ia server TruySn tai Nhiem vu ctia client C in doi N S n g client Phan tich Duyet ban d6 Truy v^n dQr lidu Phan tich V § b^n d6 Truy vSn dO lieu Phan tich V e ban d6 Ban d6 Raster d(i lieu Raster/vector Ban 6 vector H iln thi H iln th j Duyet ban d6 Truy van dau vao H iln thj DuySt d6 Truy van dO lieu G IS tren clien t Dich vu tep Vg ban d6 ban DO lieu the Hien thi D u yft ban d6 Truy van dO lieu V§ ban Phan tich Chifdng He thong tin dja ly va Internet 261 S erver Muc tidu co ban cua md hinh tmh toan khach/chu la tap trung dtf lieu va phdn mem tren mdt may dd cac client xam nhap Thdng thuctng thi vide tap trung du lieu va phan mem tren mdt may (hay goi la nang server) co nhieu loi the' nhu dd cap nhat, sir dung may tmh manh se hidu qua hctn’vidc phan tan moi thu: va de quan ly xam nhap thdng tin Ne'u dat du lieu GIS tren may trung tarn thi ta c6 ke't qua tuctng tu nhu mdi tructng Web Tuy nhien chung cung co bat Id , la he GIS doi hoi server manh de thuc thi nhilu cdng viec hon cac trang chu Web thdng thuong khac Do vay, qua nhieu ngucn sir dung xam nhap trang chu thi bd xur ly qua tai dan de'n ducng hoat ddng Do la nguydn nhan de xay dimg may chu tren co set nhieu bo xvr ly chay song song Van de khac xay v d ling dung GIS phan tan nang server la qua tai ductng truy^n Internet Mdi ngud dung phong to, thu nho ban dd thi ydu cSu m d duoc gui tir client de'n server, ban d6 m d ductc server phat sinh va gui trer lai client Chung co the lam tac ductng truydn hay lam giam tmh tuctng tac va tfnh hidu qua cua giao didn v d ngud su dung C lient Thdng thudng cac trinh duydt Web thuoc nhom client mong, phdn ldn cac xu ly ductc thuc hidn trdn server va trinh duydt chi lam nhidm vu hien thi Cac dig dung trdn client mong doi hoi server nang nhu md ta trdn day Nguoc lai, cac ling dung xay dung trdn quan diem client nang se thuc hidn nhidu xir ly trdn client Nd'u trinh duydt co kha nang dd hoa cao va xir ly nhidu chiic nang GIS thi chung co thd dd dang duydt, phdng to, thu nho ban dd va truy vtfn du lidu khdng gian Chung lam giam tai ductng truydn va bd xir ly cua server Tuy nhidn, cac nha phat trid’n trinh duydt Web thdng thuctng khdng mud'n xay diing cac chiic nang GIS cho hd thdng chuctng trinh cua ho Nhung ho da cho kha nang met 262 Hg THONG THONG TIN DjA LY rdng chirc nang trinh duyet Web bang cac cong nghe khac nhu Java applet, ActiveX, plug-ins Java applet dupe xay dung bang ngon ngu lap trinh Java cua Sun Microsystems Java cho phep vidt mot trinh ung dung hay mot doan ma trinh (applet) tren he didu hanh va chay no tren bat cu may tinh nao khac neu co moi trudng Java ma khdng cdn phai dich lai applet Dieu khidn ActiveX Ih nhung phan lap trinh hudng ddi tupng tren nen he didu hanh Windows Didu khien ActiveX cung cap nhieu chuc nang tuong tu nhu Java applet Tuy nhien, dupe xay dung bang cPng ngh6 md rpng cua Microsoft cho nen chung chi chay tren PC co moi trucmg he dieu hanh va trinh duyet Web cua Microsoft Plug-in cung cho kha nang tuong tac vdi ngudi dung Web Plug-in la thu vien lien ket dpng (DLL) cho phep nhin, nghe loai du lieu moi Chung dupe cai dat de chay ben cira sd duyet, sudt vdi ngudi su dung Chung co kha nang xam nhap tai nguyen cua client nhu cac dd'i tupng OLE, thiet bi MIDI, may in Khi ngudi sir dung goi trang chu thi applet dupe tu dong nap va trd mdt phan cua trinh duyet Dieu cho ngudi phat trien phan mem GIS xay dung cac applet xft ly dir lieu khdng gian cua rieng ho Bat lpi cua giai phap la cac may client phai nap cac applet (co ldn tdi megabyte) mdi xam nhap trang chu Can doi server/clien t Viec lua chon giai phap nang hay nhe may chu phu thuoc vao nhieu yeu td Client nang tuong tac vdi server nhe cho kha nang phan tich mem deo va phong phu horn, lam giam tai dudng truydn, tang so' lupng ngudi dung ddng thdi va cap nhat phan mem kho khan hon Cai dat client nhe/server nang chiem dung giai bang truyen tin dang kd dd tai cac ban dd Giai phap danh cho cac ung dung Chirong He thdng tin dja ly va Internet 263 khong doi hoi cac thao tac phan tich GIS phuc tap 2 Cac loai ufng dung thong tin dia ly trtfc tuyen Cac loai trang chu tren Internet tich hop vdi GIS dupe phan biet vdi theo cac dac tnmg cua no Sau day la m6 ta cua m6t vai loai ca'u true co ban T d i d v t lie u th o Trong kien true server lam nhiem vu cung ca'p cac tep thong qua cac dich vu FTP hay HTTP (hinh 7.13) Tap dir lieu dupe dat tep va tai true tiep tur GIS tren server v6 client Thong thuemg cac tap du lieu dupe dat he thdng tep ma mang "nhin" tha'y dupe Sau du lieu dupe nap vao dia mem tren client thi GIS tren client co the lam vide ddc lap, che' dd ngoai tuydn (off-line) Co the’ tim tha'y thi du cua ky thuat tren trang chu http :llnsdi ugs.gov/nsdi Hinh 7.13 So kien true ta i d iflie u tho 264 HE THONG THONG TIN P jA LY Hien thi , * ban tinh Day la giai phap don gian nha't Cac ban d6 duqc tao lap nhcr he thong GIS hay cac phSn mfim d6 hoa r6i luu tru chung dirdi khudn dang bitmap hay vecto de quan sat trinh duyet Web Cac khudn m iu thong thucfng duqc sir dung la GIF va JPEG cho ban d6 raster va CGM, DXF cho ban d6 vecto Khudn m lu vecto doi hoi cai dat cac doan trinh hien thi plug-ins hay ActiveX Mdt ban duqc tao lap thi cung duqc phan phat tren Web nhu cac anh d6 hoa thdng thudng, chung duqc quan sat trinh duyet Web nhu mdt phan cua tai lieu HTML Hinh 7.14 md ta kien true Mdt dich vu ban d6 true tuyen xay dung tren co so kien true hien thi ban d6 tinh duqc su dung tai trucmg Dai hoc Texas co dia chi nhu sau: http://www.lib.utexas.edu/libs/PCL/Map_collection/Map_collection.html Hinh 7.14 So d kien true hien th j ban ffnh Duyet ban dong Day la kien true duqc sur dung rdng rai de phan phd'i cac thdng tin dia ly Ban d6 khdng phai la tinh ma vide tao lap cua no phu thude vao tham s6 nhan duqc nhu ty le, vi tri, lop Ban d6 duqc tao lap tir GIS chuan (thi du Arc View) Chuang He thong tin dja ly va internet 265 th6ng qua trinh giao dien hay duqc phat sinh tiif trinh phat sinh ban d6 dac biet Server ve ban d6 nhu anh raster va client se hidn thi chung M6i ngudi dung thay d