union

Computes the union of geometry a with geometry b. The result is a geometry that contains all points that are in either geometry a or geometry b.

Parameters

Name	Type	Description
a	Geometry	First geometry
b	Geometry	Second geometry
options?	object	Optional options object
options.gridSize?	number	Precision grid cell size for snapping vertices. If 0 or when not defined, the highest precision is used (IEE754 double), which provides almost 16 decimal digits of precision. If nonzero, input as well as resulting coordinates will be snapped to a precision grid of that size.

Returns

Geometry

A new geometry representing the union

Examples

union of two polygons

const a = fromWKT('POLYGON ((10.01 10, 10 5, 5 5, 5 10, 10.01 10))');
const b = fromWKT('POLYGON ((10 15, 15 15, 15 7, 10.01 7, 10 15))');
const ab_union = union(a, b);
 // 'POLYGON ((10 5, 5 5, 5 10, 10.00625 10, 10 15, 15 15, 15 7, 10.01 7, 10.007692307692308 8.846153846153847, 10 5))'
const ab_union_pg = union(a, b, { gridSize: 0.1 });
 // 'POLYGON ((10 5, 5 5, 5 10, 10 10, 10 15, 15 15, 15 7, 10 7, 10 5))'

const a = fromWKT('POLYGON ((10.01 10, 10 5, 5 5, 5 10, 10.01 10))'); const b = fromWKT('POLYGON ((10 15, 15 15, 15 7, 10.01 7, 10 15))'); const ab_union = union(a, b); // 'POLYGON ((10 5, 5 5, 5 10, 10.00625 10, 10 15, 15 15, 15 7, 10.01 7, 10.007692307692308 8.846153846153847, 10 5))' const ab_union_pg = union(a, b, { gridSize: 0.1 }); // 'POLYGON ((10 5, 5 5, 5 10, 10 10, 10 15, 15 15, 15 7, 10 7, 10 5))'