Shoelace-formula signed area of a closed 2D polygon, expressed
as a tuple array of vertices in walk order. Sign indicates
orientation — positive when the polygon is wound CCW (in
the usual math y-up convention) or CW (in image y-down
convention with the 1-region on the LEFT of the contour walk).
Magnitude is the unsigned area.
The first vertex does NOT need to be repeated at the end — the
loop closes implicitly.
Shoelace-formula signed area of a closed 2D polygon, expressed as a tuple array of vertices in walk order. Sign indicates orientation — positive when the polygon is wound CCW (in the usual math y-up convention) or CW (in image y-down convention with the 1-region on the LEFT of the contour walk). Magnitude is the unsigned area.
The first vertex does NOT need to be repeated at the end — the loop closes implicitly.