Transcript LAMBERT (Conic) Projections

What is a projection?
• A map projection is used to portray all or
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part of the spherical Earth on a flat
surface. This cannot be done without some
distortion
Every projection has its own set of
advantages and disadvantages. There is no
"best" projection
In GIS we must select the one best suited
to our needs, reducing distortion of the
most important features
Chart Projections
Three main types
LAMBERT (Conic)
GNOMONIC (Azimuthal)
MERCATOR (Cylindrical)
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)
Azimuthal—Geometrically projected on a plane. Point of
projection is the center of a globe.
GNOMONIC (Azimuthal)
GNOMONIC (Azimuthal)
• Used by some navigators to find the shortest path
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between two points. Used in seismic work because
seismic waves tend to travel along great circles.
Any straight line drawn on the map is on a great circle,
but directions are true only from center point of
projection. Map is perspective (from the center of the
Earth onto a tangent plane) but not conformal, equal
area, or equidistant.
Considered to be the oldest projection. Ascribed to
Thales, the father of abstract geometry, who lived in the
6th century B.C.
Mercator
• Used for navigation
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or maps of equatorial
regions.
Any straight line on
the map is a rhumb
line (line of constant
direction).
Directions along a
rhumb line are true
between any two
points on map
Gerardus Mercator (1512-1594)
MERCATOR (Cylindrical) projections
result from projecting a spherical surface onto a cylinder.
MERCATOR (Cylindrical) projections
.
Features of Mercator
• Distances are true only along Equator, but are
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reasonably correct within 15° of Equator.
Areas and shapes of large areas are distorted.
Distortion increases away from Equator and is
extreme in polar regions. The map is not
perspective, equal area, or equidistant.
Equator and other parallels are straight lines and
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 Scale
The size of the area represented in a chart varies in
according to the scale of the chart
Charts with a small scale will cover a large area
Charts with a large scale will cover a small area
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TURKISH NAUTICAL CHART
GENEL HARİTALAR : 1/600.000 – 1/150.000
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PARÇA HARİTALAR : 1/150.000 – 1/50.000
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PORTOLONLAR
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: 1/50.000 den büyük
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TURKISH NAUTICAL CHART
Turkish Nautical charts are divided 3 region
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