hai do s091212

2.Hi .

2.1.c im php chiu Mercator.

2.2.c im php chiu Gnomonic.

2.3.Danh mc hi .

2.4.Phn loi hi Vit nam.

2.5.Phn loi hi Anh.

2.6.Hi quc t.

2.7.Mc tin cy ca hi .

2.8.Ti liu tham kho.

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2.1.c im php chiuMercator.

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.1.Php chiu a cu ln mt tr.

kinh tuyn dc theo ng sinh mt tr lnhng ng thng song song.

v tuyn cng song song vi nhau v vung gcvi cc ng kinh tuyn

.2.php chiu bo m tnh ng gic.

.3. ng loc xo trn hi l ng thng.

.4. bin dng php chiu trong gii hn chophp.



o khong cch s dng n v trn bindc.

o hng dng hoa la bn.


2.2.c im php chiuGnomonic.



1.Php chiu a cu ln mt phng.

Hnh chiu ca cc ng kinh tuyn l nhngng thng quy t ti 1 im.

Hnh chiu ca cc v tuyn l nhng cunghypebol, parabol hoc elip .

.2. Php chiu khng m bo tnh ng gic vng tch.

.3. Hnh chiu ca ng Oc t v cung vng lnl nhng ng thng.



.4. bin dng php chiu trong gii hncho php.

o khong cch s dng n thc t l.

o hng dng hoa la bn.


2.3.Danh mc hi .

.1. S danh mc hi v danh mc cc n phmhng hi NP 131 ( Catalogues of Admiralty charts and publications).

.2. Danh mc hi xut bn hng nm cungcp thng tin v tt c cc s hi hin ccng nh nhng xut bn mi.

.3. tm hi ,s quan hng hi phi tm khuvc bin m mnh quan tm, chng c phnvng theo th t (t A n X). T c th tmc cc hi .


2.3.Danh mc hi .

Cc hi c t l xch ln hn s nmtrong phm vi ca hi c t l xch nh.

.4.Ta cng c th tm tn cc vng, t tm c cc trang. Trong mi trang cavng l danh sch cc hi .



.1.Tng : T l xch thng nh hn1:500.000. Thng tin trn hi nykhng c chnh xc. Ngi ta s dngn hnh hi xa b.

.2. Hi ven bin: T l xch thng t1:200.000 - 1:300.000. chnh xc chophp dng thao tc ng i ca tuv dng hnh trnh gn b.



.3. Cc hi c t l xch ln, thng c tl ln hn 1:100.000. chnh xc cahi ln, nhng bao ph trn mt dintch nh, v vy ngi ta ch dng khi phihnh hi qua khu vc .

.4. Bnh c t l xch ln (1: 10.000).


2.5.Phn loi hi Anh.

.1. Ocean charts: c t l t 1:1.800.000 n1:5.000.000, c s dng din tmt khu vc ln, c tnh tham kho v kng i s b chn cc hi chotuyn hnh trnh.

.2. General charts: c t l t 1: 350.000 1:3.500.000, s dng hnh hi ngoikhi.


2.5.Phn loi hi Anh.

.3. Coast charts: c t l t 1:50.000 1:350.000, s dng cho tu hnh hi ven b .

.4. Plan charts: c t l t 1: 1.000 1:25.000.

.5. Special charts (Hi chuyn dng): t l t1:750.000 3.500.000, ch dng xc nh vtr tu, khng nn dng thao tc ng i vdn tu, v trn khng th hin y ccthng tin v chng ngi vt.


2.5.Phn loi hi Anh.

.6. Hi trng (ploting sheets):

y l nhng t hi c dng theophp chiu Mercator, trn ch c ccng kinh tuyn v v tuyn.

Hi ny dng chung c Bc v Nam bn cu.


2.6.Hi quc t.

.1. Trn u mc hi c in ch INT,Hi quc t International Charts (INT).

.2. Khi mt nc thnh vin xut bn hi quc t th cc nc thnh vin khc cquyn sao chp li.

.3. Nu quc gia c xut bn hi quct th c hai biu tng quc gia,quc tIHO phi c t cnh nhau.



.1. Thi gian gim nh s liu kho st v thigian tu chnh hi .

Nhng hi m thi gian gim nh cng gnthi gian s dng hoc c tu chnh mi thc tin cy cng ln.

Nhng hi da vo s liu gim nh rt cs khng chnh xc do k thut gim nh cnlc hu. S liu ngy, thng, nm xut bn vhiu chnh c ghi gc bn tri, pha dihi .



.2. T l hi .Hi c t l xch cng ln th cng th hinc chi tit v chnh xc cng cao.Theo quy nh ca SOLAS phi dng hi c tl xch ln nht vi mc ch ph hp. phn gii ca mt 0.1mm ,lin quan n chnh xc gii hn ca hi .

.3. Gi tr su ghi trn hi : Nu su c ghi mt cch lin tc, c hthng, mt dy c th chng t y bin c kho st k cng v tin cy s cao.



chnh xc khi tc nghip hi 0.2mm.

02 millimetres at a scale of 1:10 000 is 2 metres.02 millimetres at a scale of 1:50 000 is 10 metres.02 millimetres at a scale of 1:150 000 is 30 metres.

.3. Gi tr su ghi trn hi : Nu su c ghi mt cch lin tc, c h thng, mt dy c th chng t y bin c kho st kcng v tin cy s cao.



Hi c nhng khong trng khngc ghi su hoc c nhng ngng su ngt qung th chng t vickho st y bin cha y v nh vycha ng tin cy.

.4.Hnh th v cht ca y bin.

.5. Ngun gc ca hi .



Hi do cc nc km pht trin xutbn s c tin cy km.

Hi do cc nc c nn khoa hc kthut pht trin pht hnh c tin cycao.

Hi do cc nc pht trin pht hnhnhng s dng s liu ca cc nc kmpht trin cng c tin cy km.



.6.Mc trc a,qu c,khng ph hp viWGS.

Mt s hi c khuyn co rng vic xcnh v tr tu bng h GPS s c chnh xc khng xc nh c.



5108'39N 122'37E Referred to OSGB(36) Datum(the local datum for the United Kingdom)

5108'47N 122'35E Referred to European (1950)Datum (the Continental datum)

5108'42N 122'27E Referred to World GeodeticSystem 1984 (WGS84) Datum(theworld-wide datum usedby Global Positioning System(GPS).



.7.Sai s do bin son hi t nhiu ngun sliu khc nhau.

Transformations to have an accuracy of 03millimetres at chart scale.

03 millimetres at a scale of 1:10 000 is 3 metres.





Soundings .In the past, the traditional method of sounding was by keeping a boat or vessel on lines producing a systematic series of profiles covering the entire area. These lines are usually run 5 mm apart on thesheet, eg on a scale of 1:12 500 lines are run 62 m apart on the ground. The scale of the survey must be large enough to allow sufficient lines to be plotted to indicate the configuration of the sea floor .



Light Detection and Ranging (LIDAR) is the generic term used for a number of systems that use laser pulses tomeasure depth. The red laser signal reflects from the sea surface while the green laser signal penetrates the water and reflects from the sea floor with a foot print of about half the water depth.


Cm n.


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