lonlat2ECEF: Conversions of Coordinates

In emmanuelparadis/sentinel: Sentinel

Conversions of Coordinates

Description

Conversion between lon-lat and ECEF (Earth-centered, Earth-fixed) coordinates.

Usage

lonlat2ECEF(lon, lat = NULL, alt = 0, as.matrix = TRUE)
ECEF2lonlat(x, y = NULL, z = NULL)

Arguments

lon, lat	coordinates given as two vectors or as a matrix (or a data frame).
alt	a vector of altitudes.
as.matrix	a logical value specifying whether to return the results in a matrix. The default is to return them in a list.
x, y, z	three numeric vectors of the same length, or only x as a three-column matrix.

Details

This function uses an ellopsoid model of Earth shape with the following parameters: equatorial radius = 6,378,137 m, polar radius = 6,356,752 m.

Value

lonlat2ECEF returns a matrix with three columns or a list with three vectors; ECEF2lonlat returns a matrix with three columns.

Author(s)

Emmanuel Paradis

References

Blewitt, G. (2024) An improved equation of latitude and a global system of graticule distance coordinates. Journal of Geodesy, 98, 6.

Examples

## From Blewitt's Table 1:
DF <- expand.grid(alt = c(1, 4, 10, 40) *1e3,
                  lat = seq(15, 75, 15),
                  lon = 0)
DF <- as.matrix(DF[3:1])

x <- lonlat2ECEF(DF[, -3], alt = DF[, 3], as.matrix = TRUE)

DFbis <- ECEF2lonlat(x)
xbis <- lonlat2ECEF(DFbis[, -3], alt = DFbis[, 3], as.matrix = TRUE)

summary(x - xbis)
summary(DF - DFbis)

emmanuelparadis/sentinel documentation built on May 2, 2024, 4:52 a.m.