Calculate the area of a polygon

Functions to calculate different types of area for polygons.

Usage

signed_area(x)

unsigned_area(x)

signed_area_cd(x)

unsigned_area_cd(x)

signed_area_geodesic(x)

unsigned_area_geodesic(x)

Arguments

x

an object of class rsgeo

Value

a numeric vector of the area contained by the geometry

Details

• functions assume counter clock-wise winding in accordance with the simple feature access standard

• functions ending in _cd use the Chamberlain-Duquette algorithm for spherical area

• Chamberlain-Duquette and Geodesic areas are returned in meters squared and assume non-planar geometries

See geo docs for more:

• GeodesicArea

• Area

• ChamberlainDuquetteArea

x <- c(0, 1, 1, 0, 0) y <- c(0, 0, 1, 1, 0) p <- geom_polygon(x, y)

signed_area(p) unsigned_area(p) signed_area_cd(p) unsigned_area_cd(p) signed_area_geodesic(p) unsigned_area_geodesic(p)