Reference Ellipsoid and the Geodetic Coordinate System - Geodesy: Introduction to Geodetic Datum and Geodetic Systems - page 170

5.2.2 Geometric Parameters of the Reference Ellipsoid
and Their Correlations

The six commonly used geometric parameters in the Earth ellipsoid are as follows:

9
=

Semimajor axis a
Semiminor axis b
Polar radius of curvature c

a 2
b

ﾼ

a b

Flattening f ﾼ

a

ð 5 : 9 Þ

p

a 2

;

b 2

First eccentricity e ﾼ

a

p

a 2 b 2

Second eccentricity e 0 ﾼ

b

Out of the six parameters, given a single length parameter and another arbitrary
parameter, the size and shape of the ellipsoid will be defined. In geodesy, a and f are
customarily used to represent the geometric shape of the Earth ellipsoid.
Beijing Geodetic Coordinate System 1954 of China adopted the Krassowski
Ellipsoid (see Table 4.1 ). Its parameters are as follows:

a ﾼ 6,378,245.0000 m

b ﾼ 6,356,863.0188 m

c ﾼ 6,399,698.9018 m

f ﾼ 1/298.3 ﾼ 0.00335232986926

e 2 ﾼ 0.00669342162297

e 0 2

ﾼ 0.00673852541468

Xi'an Geodetic Coordinate System 1980 of China adopted the Geodetic Refer-
ence System 1975 (GRS75) reference ellipsoid recommended by International
Union of Geodesy and Geophysics (IUGG) in 1975, also referred to as the
IUGG-1975 Ellipsoid. Its geometric parameters are:

a ﾼ 6,378,140.0000 m

b ﾼ 6,356,755.2882 m

c ﾼ 6,399,596.6520 m

f ﾼ 1/298.257 ﾼ 0.00335281317790

e 2

ﾼ 0.00669438499959

e 02 ﾼ 0.00673950181947

China Geodetic Coordinate System 2000 (CGCS2000) basically adopted the
Geodetic Reference System 1980 (GRS80) recommended by IUGG in 1980 [GM