earth.poly {fossil}

Calculating a Minimum Convex Polygon

Description

Calculate a minimum convex polygon for a collection of points without knowing what points form the vertices.

Usage

earth.poly(lats)

Arguments

lats

a table with a longitude and latitude column respectively as the first two columns, or a SpatialPoints object with longitude/latitude

Details

This function will calculate the area of a minimum convex polygon/convex hull for a spherical surface (ie points on a globe).

Value

The function will return a list consisting of the area in $km^2$ (\$area) and a vector with the row numbers of the vertices (\$vertices)

Author(s)

Matthew Vavrek

See Also

earth.tri

Examples

#1/8th the surface area of the earth
a <- matrix(c(0, 0, 0, 90, 90, 0, 25, 25), 4, 2, byrow = TRUE)
earth.poly(a)