Transcript Map Projections

Map Projections
GIS-101 Summer 2006
Semester
Important Things to Remember about
Map Projections
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An attempt to take location information from
a spheriod object and transfer to a flat
surface
As such, ALL projections are a distortion of
the real world to some extent!
Attributes of Distortion
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Shape
Size
Distance
Direction
Area
Map Projections versus Coordinate
Systems
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REMEMBER: Map Projections and
Coordinate Systems are two different things!
Factors Associated with Map
Projections
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Scale
Map Units
Projection
Coordinate System
Datum
Map Scale vs Spatial Scale
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1:24,000 is a LARGER scale than 1:100,000
e.g. 1/24,000 is a larger number than
1/100,000
However, 1:24,000 however covers a smaller
spatial scale than 1:100,000 (i.e. less area
covered on a same sized map)
Topographic Mapping System
Examples of Projections
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Robinson
Lambert Conformal Conic
Mercator
Transverse Mercator
Types or “Families” of Map Projections
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Cylindrical
Conic
Azimuthal or Planar
Orthographic Projection
Orthographic Projection
Lambert Conformal Conic
Azimuthal Projection
Transverse Mercator
Mercator Projection
Examples of Coordinate Systems
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Latitude and Longitude (Geographic)
Universal Transverse Mercator
State Plane
Geographic Coordinate System
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Latitude & Longitude
NOT a true “Projection”
Latitude / Longitude for US
UTM Grid
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Uses Transverse Mercator projection
Units usually in meters
60 Zones
6 degrees per zone
“N” or “S”
Example:
UTM Coordinate System (US)
UTM Coordinate System
State Plane
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Uses either Lambert Conformal Conic (EastWest States) OR Transverse Mercator
(North-South States) Projections
Units usually in feet
State Plane Coordinate System
Township & Range System