# Method Union

#### Union(Geometry, Geometry)

The union operation constructs the set-theoretic union of the geometries in the input array.

##### Declaration

`public static Geometry Union(this Geometry geometry1, Geometry geometry2)`

##### Parameters

Type | Name | Description |
---|---|---|

Geometry | geometry1 | The first geometry to union with. |

Geometry | geometry2 | The second geometry to union with. |

##### Returns

Type | Description |
---|---|

Geometry | The union of the two geometries. |

##### Remarks

GeometryEngine.Union returns all parts of the two input geometries combined into a single geometry. This means that the
order of the input parameters is irrelevant. In a theoretical variable format
you can think of the GeometryEngine.Union equation like:

A (Union) B = C

B (Union) A = C

The following is a visual illustration of two polygon geometries and how the output result would be from the GeometryEngine.Union operation:

If the two geometries have different dimensionality, returns a copy of the geometry with the higher dimensionality. E.g. if given a polygon and a point, returns the polygon.

Supports true curves.

### Applies to

## Platforms and versions

Target | Versions |
---|---|

.NET Standard 2.0 | 100.3 - 200.1 |

.NET 6.0 | 100.13 - 200.1 |

.NET 6.0 Windows | 100.13 - 200.1 |

.NET 6.0 Android | 200.0 - 200.1 |

.NET 6.0 iOS | 200.0 - 200.1 |

.NET Framework | 100.0 - 200.1 |

.NET 5 | 100.10 - 100.12 |

.NET Core 3.1 | 100.7 - 100.12 |

Android | 100.0 - 100.15 |

iOS | 100.0 - 100.15 |

UWP | 100.0 - 200.1 |

##### Relevant samples

#### Union(IEnumerable<Geometry>)

Calculates the union of a collection of geometries

##### Declaration

`public static Geometry Union(this IEnumerable<Geometry> geometries)`

##### Parameters

Type | Name | Description |
---|---|---|

IEnumerable<Geometry> | geometries | A collection of geometries. |

##### Returns

Type | Description |
---|---|

Geometry | The union of all the geometries in the given collection. |

##### Remarks

There must be at least one geometry in the given collection. The geometries must have consistent spatial references. If the collection contains geometries of differing dimensionality, returns the union of the subset of geometries with the highest dimensionality. E.g. given a collection of polygons, polylines and points, returns the union of the polygons.

Supports true curves.

### Applies to

## Platforms and versions

Target | Versions |
---|---|

.NET Standard 2.0 | 100.3 - 200.1 |

.NET 6.0 | 100.13 - 200.1 |

.NET 6.0 Windows | 100.13 - 200.1 |

.NET 6.0 iOS | 200.0 - 200.1 |

.NET Framework | 100.1 - 200.1 |

.NET 5 | 100.10 - 100.12 |

.NET Core 3.1 | 100.7 - 100.12 |

Android | 100.1 - 100.14 |

iOS | 100.1 - 100.15 |

UWP | 100.1 - 200.1 |