icosa: PolToCar – R documentation

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PolToCar

Conversion of polar coordinates to 3d Cartesian coordinates

Description

The function uses basic trigonometric relationships to transform longitude/latitude coordinates on a sphere to xyz Cartesian coordinates.

Usage

PolToCar(x, ...)

## S4 method for signature 'matrix'
PolToCar(x, radius = authRadius, origin = c(0, 0, 0))

## S4 method for signature 'numeric'
PolToCar(x, radius = authRadius, origin = c(0, 0, 0))

## S4 method for signature 'data.frame'
PolToCar(x, radius = authRadius, origin = c(0, 0, 0), long = NULL, lat = NULL)

Arguments

`x`	(`matrix`, `numeric`, `data.frame`) A 2-column `numeric` matrix with the longitude/latitude data.
`...`	Arguments passed to class-specific methods.
`radius`	(`numeric`) The radius of the sphere. Defaults to the R2 radius of Earth (6371.007km).
`origin`	(`numeric`) Vector with length `3`, the XYZ coordinates of the sphere center.
`long`	(`character`) If `x` is a `data.frame`, then the column used as longitudes.
`lat`	(`character`) If `x` is a `data.frame`, then the column used as latitudes.

Details

The authalic mean radius of Earth (6371.007 km) is used by this function as a default. The origin is c(0,0,0). The precision of these conversions is not exact (see example c(0,90) below), but should be considered acceptable when applied at a reasonable scale (e.g. for global analyses using data above 10e-6 meters of resolution).

Value

An xyz 3-column numeric matrix, data.frame or numeric, depending on the class of x.

Examples

longLat <- rbind(
  c(0,0),
  #note the precision here!
  c(0, 90),
  c(-45,12)
)
# matrix-method
xyz <- PolToCar(longLat)
# numeric-method
xyz2 <- PolToCar(longLat[1,])
# data.frame method
xyz3 <- PolToCar(as.data.frame(longLat))

icosa

Global Triangular and Penta-Hexagonal Grids Based on Tessellated Icosahedra

v0.10.1

GPL-3

Authors

Adam T. Kocsis [aut, cre]

Initial release

2021-01-12