Build Tissot indicatrix objects — indicatrix • tissot

Computes an indicatrix_list containing per-point distortion objects suitable for plotting with plot.indicatrix_list() or querying directly.

Usage

indicatrix(x, target = NULL, ..., source = "EPSG:4326")

Arguments

x: a tissot_tbl, or any xy-ish input (see tissot())
target: target projection CRS (extracted from tissot_tbl attributes if x is one; required otherwise)
...: passed to tissot()
source: source CRS (default "EPSG:4326")

Value

An indicatrix_list object (a list of indicatrix objects with source and target stored as attributes)

Details

indicatrix() accepts either:

A tissot_tbl object (from tissot()) — projection is extracted from attributes, target is optional
Any xy-ish input with an explicit target

See also

tissot(), plot.indicatrix(), plot.indicatrix_list(), ti_ellipse()

Examples

## From a tissot_tbl
r <- tissot(cbind(seq(-150, 150, by = 30), 0), "+proj=robin")
ii <- indicatrix(r)
plot(ii, scale = 5e5)


## From raw coordinates
ii2 <- indicatrix(c(0, 45), "+proj=stere +lat_0=90")
plot(ii2)