Map Projections

The Earth needs to be transformed. The Earth is a spheroid A mathematical conversion must be used to create a flat map sheet from the three-dimensional surface. The Earth needs to be transformed.

Projection is a mathematical procedure of representing the globe on a flat surface.

How do you put a round surface on a flat paper ? Mathematically, a projection is a process of transforming global location to a planar position. Planar coordinate systems: Have two dimensions, X measures distance in a horizontal direction Y measures distance in a vertical direction Measures of length, angle, and area are constant across the dimension

Different Acronyms UTM = Universe Transverse Mercator WGS = World Geodetic System NAD = North American Datum GRS = Geodetic Reference System Oblate Ellipsoid or Spheroid

The Earth is not a ball 1924 measurements were: e = 6,378,206.4 P = 6,356,538.8 m Or: f = 1/297 1980 (GRC80) Geodetic Reference System 1983 (NAD83) WGS84 World Geodetic System F = 1/300 e p F = 1-p/e NAD1927 (North American Datum)

Any representation of the earth’s surface in two dimensions: Causes some distortion: 4 types of distortion: Shape area distance direction Different projections produce different distortions

Some commonly used map projections in the U.S. and North America

UTM a Planar Coordinate System

Latitude and Longitude Is a geographic referencing system NOT a projection

UTM Zone 13

Lambert Conformal Conic

Albers Equal-Area Conic

Assignment – Projections of the World Create a map showing at least 4 different world projections (different data frames). Indicate on the map each projection Include a title, and scale of each map Design your layout to maximize your space Print your map on 17 x 11 inch paper