Class: PolygonArea

GeographicLib/PolygonArea. PolygonArea

Computes the area and perimeter of a geodesic polygon. This object is usually instantiated by Geodesic.Polygon.

Constructor

new PolygonArea(geod, polylineopt)

Initialize a PolygonArea object.

Parameters:
Name Type Attributes Default Description
geod object

a Geodesic object.

polyline bool <optional>
false

if true the new PolygonArea object describes a polyline instead of a polygon.

Properties:
Name Type Description
a number

the equatorial radius (meters).

f number

the flattening.

polyline bool

whether the PolygonArea object describes a polyline or a polygon.

num number

the number of vertices so far.

lat number

the current latitude (degrees).

lon number

the current longitude (degrees).

Source:

Methods

AddEdge(azi, s)

Add the next edge to the polygon.

This specifies the new vertex in terms of the edge from the current vertex.

Parameters:
Name Type Description
azi number

the azimuth at the current the point (degrees).

s number

the length of the edge (meters).

Source:

AddPoint(lat, lon)

Add the next vertex to the polygon.

This adds an edge from the current vertex to the new vertex.

Parameters:
Name Type Description
lat number

the latitude of the point (degrees).

lon number

the longitude of the point (degrees).

Source:

Clear()

Clear the PolygonArea object, setting the number of vertices to 0.

Source:

Compute(reverse, sign) → {object}

Compute the perimeter and area of the polygon.

If the object is a polygon (and not a polygon), the perimeter includes the length of a final edge connecting the current point to the initial point. If the object is a polyline, then area is nan. More points can be added to the polygon after this call.

Parameters:
Name Type Description
reverse bool

if true then clockwise (instead of counter-clockwise) traversal counts as a positive area.

sign bool

if true then return a signed result for the area if the polygon is traversed in the "wrong" direction instead of returning the area for the rest of the earth.

Source:
Returns:

r where r.number is the number of vertices, r.perimeter is the perimeter (meters), and r.area (only returned if polyline is false) is the area (meters2).

Type
object

TestEdge(azi, s, reverse, sign) → {object}

Compute the perimeter and area of the polygon with a tentative new edge.

A new vertex is not added to the polygon.

Parameters:
Name Type Description
azi number

the azimuth of the edge (degrees).

s number

the length of the edge (meters).

reverse bool

if true then clockwise (instead of counter-clockwise) traversal counts as a positive area.

sign bool

if true then return a signed result for the area if the polygon is traversed in the "wrong" direction instead of returning the

Source:
Returns:

r where r.number is the number of vertices, r.perimeter is the perimeter (meters), and r.area (only returned if polyline is false) is the area (meters2).

Type
object

TestPoint(lat, lon, reverse, sign) → {object}

Compute the perimeter and area of the polygon with a tentative new vertex.

A new vertex is not added to the polygon.

Parameters:
Name Type Description
lat number

the latitude of the point (degrees).

lon number

the longitude of the point (degrees).

reverse bool

if true then clockwise (instead of counter-clockwise) traversal counts as a positive area.

sign bool

if true then return a signed result for the area if the polygon is traversed in the "wrong" direction instead of returning the

Source:
Returns:

r where r.number is the number of vertices, r.perimeter is the perimeter (meters), and r.area (only returned if polyline is false) is the area (meters2).

Type
object