The position of B (typically body) relative to E (typically Earth) is given as cartesian position vector p_EB_E, in meters ("ECEF-vector").

p_EB_E2n_EB_E(p_EB_E, a = 6378137, f = 1/298.257223563)

Arguments

p_EB_E

Cartesian position vector from E to B, decomposed in E (3x1 vector) (m)

a

Semi-major axis of the Earth ellipsoid (m, default [WGS-84] 6378137)

f

Flattening of the Earth ellipsoid (no unit, default [WGS-84] 1/298.257223563)

Value

n-vector representation of position B, decomposed in E (3x1 vector) (no unit) and depth of system B relative to the ellipsoid (z_EB = -height)

Details

The function converts to n-vector, n_EB_E and its depth, z_EB.

The calculation is exact, taking the ellipticity of the Earth into account. It is also nonsingular as both n-vector and p-vector are nonsingular (except for the center of the Earth). The default ellipsoid model used is WGS-84, but other ellipsoids (or spheres) might be specified.

References

Kenneth Gade A Nonsingular Horizontal Position Representation. The Journal of Navigation, Volume 63, Issue 03, pp 395-417, July 2010.

See also

Examples

p_EB_E <- 6371e3 * c(0.9, -1, 1.1) (n_EB_E <- p_EB_E2n_EB_E(p_EB_E))
#> $n_EB_E #> [1] 0.5170890 -0.5745433 0.6344439 #> #> $z_EB #> [1] -4702060 #>