what is a projection? a map projection is used to portray all or part of the spherical earth on a...
TRANSCRIPT
What is a projection?What is a projection?
• A map projection is used to portray all A map projection is used to portray all or part of the spherical Earth on a flat or part of the spherical Earth on a flat surface. This cannot be done without surface. This cannot be done without some distortionsome distortion
• Every projection has its own set of Every projection has its own set of advantages and disadvantages. There advantages and disadvantages. There is no "best" projectionis no "best" projection
• In GIS we must select the one best In GIS we must select the one best suited to our needs, reducing distortion suited to our needs, reducing distortion of the most important featuresof the most important features
ChartChart PProjectionsrojections
Three main typesThree main types
LAMBERT (LAMBERT (ConicConic))
GNOMONIC (GNOMONIC (AzimuthalAzimuthal) )
MERCATOR (MERCATOR (CylindricalCylindrical))
LAMBERT (Conic) projections
result from projecting a spherical surface onto a cone.
LAMBERT (Conic) Projections
Lambert Conformal Conic projection
•Area, and shape are distorted away from standard parallels. Directions are true in limited areas. Used for maps of North America. Lambert Conformal Conic projections are used for
rectangular zones with a larger east-west extent.
Ex: North Carolina, Tennessee
GNOMONIC (Azimuthal)GNOMONIC (Azimuthal)
Azimuthal—Geometrically projected on a plane. Point of projection is the center of a globe.
GNOMONIC (Azimuthal)GNOMONIC (Azimuthal)
• UsedUsed by some navigators to find the shortest by some navigators to find the shortest path between two points. Used in seismic work path between two points. Used in seismic work because seismic waves tend to travel along great because seismic waves tend to travel along great circles.circles.
• Any straight line drawn on the map is on a Any straight line drawn on the map is on a great great circlecircle, but , but directionsdirections are true are true onlyonly from center from center point of projection. Map is perspective (from the point of projection. Map is perspective (from the center of the Earth onto a tangent plane) but center of the Earth onto a tangent plane) but notnot conformal, equal area, or equidistant.conformal, equal area, or equidistant.
• Considered to be the oldest projection. Ascribed Considered to be the oldest projection. Ascribed to Thales, the father of abstract geometry, who to Thales, the father of abstract geometry, who lived in the 6th century B.C.lived in the 6th century B.C.
GNOMONIC (Azimuthal)GNOMONIC (Azimuthal)
MercatorMercator
• UsedUsed for navigation for navigation or maps of or maps of equatorial regions. equatorial regions.
• Any straight line on Any straight line on the map is athe map is a rhumb rhumb lineline (line of (line of constant direction).constant direction).
• DirectionsDirections along a along a rhumb line are true rhumb line are true between between anyany two two points on map points on map
Gerardus Mercator (1512-1594)
MERCATOR (Cylindrical) projections
result from projecting a spherical surface onto a cylinder.
MERCATOR (Cylindrical) projections
.
Features of MercatorFeatures of Mercator
• DistancesDistances are true are true onlyonly along Equator, but along Equator, but are reasonably correct within 15are reasonably correct within 15°° of Equator. of Equator.
• Areas and shapesAreas and shapes of large areas are of large areas are distorted.distorted.
• DistortionDistortion increases away from Equator and increases away from Equator and is extreme in polar regions. The map is is extreme in polar regions. The map is notnot perspective, equal area, or equidistant.perspective, equal area, or equidistant.
• Equator and other parallels are straight lines Equator and other parallels are straight lines and meet meridians at right anglesand meet meridians at right angles
WHAT IS A NAUTICAL CHART?
A Nautical Chart is a graphic portrayal of the marine environment.
In addition to its basic elements, a chart is a working document used by the mariner both as a "road map" and worksheet and is essential
for safe navigation.
Chart ScaleChart Scale
The size of the area represented in a chart varies The size of the area represented in a chart varies in according to the scale of the chartin according to the scale of the chart
Charts with a small scale will cover a large areaCharts with a small scale will cover a large areaCharts with a large scale will cover a small areaCharts with a large scale will cover a small area
1/3.000.000
1/100.000
1/40.000
1/1
1/900.000
1/150.000
TURKISH NAUTICAL CHART
GENEL HARİTALAR : 1/600.000 – 1/150.000
PARÇA HARİTALAR : 1/150.000 – 1/50.000
PORTOLONLAR : 1/50.000 den büyük
- - two digits
- - - three digits
- - - - four digits
112
3212
291
TURKISH NAUTICAL CHART
Turkish Nautical charts are divided 3 region
11
22
33
29
213
12
10
13
11
16
15
19 20
16
9
NoNo AçıklamasıAçıklaması
11 Haritanın Ulusal NumarasıHaritanın Ulusal Numarası
22 Haritanın Seyir Yardımcılarına Uygun.Haritanın Seyir Yardımcılarına Uygun.
33 Haritanın Uluslararası NumarasıHaritanın Uluslararası Numarası
99 Köşe KoordinatlarıKöşe Koordinatları
1010 Harita Başlığı veya Adı Harita Başlığı veya Adı
1111 Haritanın Projeksiyon TipiHaritanın Projeksiyon Tipi
1212 Haritayı Hazırlayan Kuruluşun AmblemiHaritayı Hazırlayan Kuruluşun Amblemi
1313 Haritanın ÖşçeğiHaritanın Öşçeği
1515 Büyük Ölçekli Haritalarda Diğer ÖlçeklerBüyük Ölçekli Haritalarda Diğer Ölçekler
1616 Uyarı NotlarıUyarı Notları
1919 Bitişik veya Devam Eden Harita No’suBitişik veya Devam Eden Harita No’su
2020 Diğer Notik BilgilerDiğer Notik Bilgiler
213
18
9
57 6a
8
17
14
NoNo AçıklamasıAçıklaması
11 Haritanın Ulusal NumarasıHaritanın Ulusal Numarası
22 Haritanın Seyir Yardımcılarına Uygun.Haritanın Seyir Yardımcılarına Uygun.
33 Haritanın Uluslararası NumarasıHaritanın Uluslararası Numarası
44 Haritayı Hazırlayan KuruluşHaritayı Hazırlayan Kuruluş
55 Telif HakkıTelif Hakkı
66 Yeni Yayın TarihiYeni Yayın Tarihi
6a6a Baskı TarihiBaskı Tarihi
619
4
NoNo AçıklamasıAçıklaması
77 Küçük DüzeltmelerKüçük Düzeltmeler
88 Haritanın İç kenarlarının BoyutlarıHaritanın İç kenarlarının Boyutları
99 Köşe KoordinatlarıKöşe Koordinatları
1414 Büyük Ölçekli Haritalarda Diğer Ölç.Büyük Ölçekli Haritalarda Diğer Ölç.
1717 Kaynak ve Veri DiyagramıKaynak ve Veri Diyagramı
1818 Büyük Ölçekli ReferanslarBüyük Ölçekli Referanslar
1919 Bitişik veya Devam Eden Harita No’suBitişik veya Devam Eden Harita No’su
