earth.poly {fossil} | R Documentation |
Calculate a minimum convex polygon for a collection of points without knowing what points form the vertices.
earth.poly(lats)
lats |
a table with a longitude and latitude column respectively as the first two columns, or a SpatialPoints object with longitude/latitude |
This function will calculate the area of a minimum convex polygon/convex hull for a spherical surface (ie points on a globe).
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
)
Matthew Vavrek
#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)