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Map Projections
GIS-101 Summer 2006 Semester
Important Things to Remember about Map Projections
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
Shape Size Distance Direction Area
Map Projections versus Coordinate Systems
REMEMBER: Map Projections and Coordinate Systems are two different things!
Factors Associated with Map Projections
Scale Map Units Projection Coordinate System Datum
Map Scale vs Spatial Scale
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
Robinson Lambert Conformal Conic Mercator Transverse Mercator
Types or “Families” of Map Projections
Cylindrical Conic Azimuthal or Planar
Orthographic Projection
Orthographic Projection
Lambert Conformal Conic
Azimuthal Projection
Transverse Mercator
Mercator Projection
Examples of Coordinate Systems
Latitude and Longitude (Geographic) Universal Transverse Mercator State Plane
Geographic Coordinate System
Latitude & Longitude NOT a true “Projection”
Latitude / Longitude for US
UTM Grid
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
Uses either Lambert Conformal Conic (East-West States) OR Transverse Mercator (North-South States) Projections
Units usually in feet
State Plane Coordinate System
Township & Range System
