(source http://www.colorado.edu/geography/gcraft/notes/datum/datum_f.html)

Geoids

Geoid models attempt to represent the surface of the entire earth over both land and ocean as though the surface resulted from gravity alone. The WGS-84 Geoid defines geoid heights for the entire earth.

Ellipsoids

Airy, 6377563.396, 299.3249646, 573.604, 0.11960023

Australian National, 6378160.0, 298.25, -23.0, -0.00081204

Bessel 1841, 6377397.155, 299.1528128, 739.845, 0.10037483

Bessel 1841 (Nambia), 6377483.865, 299.1528128, 653.135, 0.10037483

Clarke 1866, 6378206.4, 294.9786982, -69.4, -0.37264639

Clarke 1880, 6378249.145, 293.465, -112.145, -0.54750714

Everest, 6377276.345, 300.8017, 860.655, 0.28361368

Fischer 1960 (Mercury), 6378166.0, 298.3, -29.0, 0.00480795

Fischer 1968, 6378150.0, 298.3, -13..0, 0.00480795

GRS 1967, 6378160.0, 298.247167427, -23.0, -0.00113048

GRS 1980, 6378137, 298.257222101, 0.0, -0.00000016

Helmert 1906, 6378200.0, 298.3, -63.0, 0.00480795

Hough, 6378270.0, 297.0, -133.0, -0.14192702

International, 6378388.0, 297.0, -251.0.0, -0.14192702

Krassovsky, 6378245.0, 298.3, -108.0, 0.00480795

Modified Airy, 6377340.189, 299.3249646, 796.811, 0.11960023

Modified Everest, 6377304.063, 300.8017, 832.937, 0.28361368

Modified Fischer 1960, 6378155.0, 298.3, -18.0, 0.00480795

South American 1969, 6378160.0, 298.25, -23.0, -0.00081204

WGS 60, 6378165.0, 298.3, -28.0, 0.00480795

WGS 66, 6378145.0, 298.25, -8.0, -0.00081204

WGS-72, 6378135.0, 298.26, 2.0, 0.0003121057

WGS-84, 6378137.0, 298.257223563, 0.0, 0.0

Datums

Projections

(Standard parallels or meridians)

Effect of projection differences

Vetical Near-side Perspective (under Projections—custom)

Projection Geographic (Platte Carree)

Cylindrical Projections

Mercator

Miller Cylindrical

Compromise Projections

Robinson

Conic Projections

Albers Equal Area Conic

Lambert Conformal Conic

Planar Projections (azimuthal)

Gnomonic

Lambert Equal Area Azimuthal

Stereographic

UTM –

Transverse planar projection;

different standard meridians for each of 60 6-degree zones;

Origin = equator and a meridian 500,000m W of center of zone.

Great distortion with E-W distance from standard meridians; little distortion within zones

So great for large scale maps.

Usually based on NAD83. (very similar to WGS84)

Transverse Mercator (UTM) Zone 18