Source: https://gometry.monicz.dev/api/toplevel/overlay-dissolve/

# Overlay & dissolve

Binary set operations and reductions over geometry collections.

**Related:** [Constructive operations](https://gometry.monicz.dev/guide/constructive/)

## difference

Accepted call forms

```python
difference(left: Point, right: Geometry) -> Point
```

```python
difference(left: MultiPoint, right: Geometry) -> MultiPoint | Point
```

```python
difference(left: MultiPoint, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT]) -> GeometryArray[MultiPoint | Point]
```

```python
difference(left: MultiPoint, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT | None]) -> GeometryArray[MultiPoint | Point | None]
```

```python
difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point], right: Geometry | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT]) -> GeometryArray[Point]
```

```python
difference(left: Point, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT]) -> GeometryArray[Point]
```

```python
difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[MultiPoint], right: Geometry | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT]) -> GeometryArray[MultiPoint | Point]
```

```python
difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | None], right: Geometry | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT | None]) -> GeometryArray[Point | None]
```

```python
difference(left: Point, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT | None]) -> GeometryArray[Point | None]
```

```python
difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[MultiPoint | None], right: Geometry | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT | None]) -> GeometryArray[MultiPoint | Point | None]
```

```python
difference(left: Geometry, right: Geometry) -> Geometry
```

```python
difference(left: Geometry, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT]) -> GeometryArray[Geometry]
```

```python
difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT], right: Geometry) -> GeometryArray[Geometry]
```

```python
difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT], right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT]) -> GeometryArray[Geometry]
```

```python
difference(left: Geometry, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None]) -> GeometryArray[Geometry | None]
```

```python
difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None], right: Geometry) -> GeometryArray[Geometry | None]
```

```python
difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None], right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT | None]) -> GeometryArray[Geometry | None]
```

```python
difference(left: Geometry | GeometryArray[Geometry | None], right: Geometry | GeometryArray[Geometry | None]) -> Geometry | GeometryArray[Geometry | None]
```

Compute the set-theoretic difference `left - right`.

Evaluated in the coordinate plane. In a geographic CRS, topology resolves
longitude aliases, seam spellings, and pole longitudes in the CRS-native
frame; seam-crossing inputs are split into chart pieces before construction.

Parameters:

| Name | Type | Description | Default |
| --- | --- | --- | --- |
| `left` | `Geometry, GeometryArray, or iterable of Geometry or None` | Geometry to subtract from (`left`) and geometry subtracted (`right`). Scalar and batch operands broadcast pairwise; batch lengths must match. Operands must share CRS and coordinate epoch. | *required* |
| `right` | `Geometry, GeometryArray, or iterable of Geometry or None` | Geometry to subtract from (`left`) and geometry subtracted (`right`). Scalar and batch operands broadcast pairwise; batch lengths must match. Operands must share CRS and coordinate epoch. | *required* |

Returns:

| Type | Description |
| --- | --- |
| `Geometry or GeometryArray` | One result per input pair; missing rows remain missing. |

Raises:

| Type | Description |
| --- | --- |
| `CRSMismatchError` | If the operands' CRS or coordinate-epoch metadata differ. |
| `InvalidGeometryError` | If either operand has coordinates outside its geographic CRS domain. |
| `OverflowError` | If no adjacent binary64 assignment preserves the exact result topology. |
| `ResourceLimitError` | If the bounded embedding search is exhausted. |

Examples:

```pycon
>>> import gometry as gm
>>> left, right = gm.box(0, 0, 2, 1), gm.box(1, 0, 2, 1)
>>> gm.difference(left, right).to_wkt()
'POLYGON ((0 0, 1 0, 1 1, 0 1, 0 0))'
```

## intersection

Accepted call forms

```python
intersection(left: Point, right: Geometry) -> Point
```

```python
intersection(left: Geometry, right: Point) -> Point
```

```python
intersection(left: MultiPoint, right: Geometry) -> MultiPoint | Point
```

```python
intersection(left: Geometry, right: MultiPoint) -> MultiPoint | Point
```

```python
intersection(left: MultiPoint, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT]) -> GeometryArray[MultiPoint | Point]
```

```python
intersection(left: MultiPoint, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT | None]) -> GeometryArray[MultiPoint | Point | None]
```

```python
intersection(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point], right: Geometry | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT]) -> GeometryArray[Point]
```

```python
intersection(left: Point, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT]) -> GeometryArray[Point]
```

```python
intersection(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT], right: Point | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point]) -> GeometryArray[Point]
```

```python
intersection(left: Geometry, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point]) -> GeometryArray[Point]
```

```python
intersection(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[MultiPoint], right: Geometry | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT]) -> GeometryArray[MultiPoint | Point]
```

```python
intersection(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT], right: MultiPoint | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[MultiPoint]) -> GeometryArray[MultiPoint | Point]
```

```python
intersection(left: Geometry, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[MultiPoint]) -> GeometryArray[MultiPoint | Point]
```

```python
intersection(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | None], right: Geometry | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT | None]) -> GeometryArray[Point | None]
```

```python
intersection(left: Point, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT | None]) -> GeometryArray[Point | None]
```

```python
intersection(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None], right: Point | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | None]) -> GeometryArray[Point | None]
```

```python
intersection(left: Geometry, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | None]) -> GeometryArray[Point | None]
```

```python
intersection(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[MultiPoint | None], right: Geometry | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT | None]) -> GeometryArray[MultiPoint | Point | None]
```

```python
intersection(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None], right: MultiPoint | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[MultiPoint | None]) -> GeometryArray[MultiPoint | Point | None]
```

```python
intersection(left: Geometry, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[MultiPoint | None]) -> GeometryArray[MultiPoint | Point | None]
```

```python
intersection(left: Geometry, right: Geometry) -> Geometry
```

```python
intersection(left: Geometry, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT]) -> GeometryArray[Geometry]
```

```python
intersection(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT], right: Geometry) -> GeometryArray[Geometry]
```

```python
intersection(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT], right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT]) -> GeometryArray[Geometry]
```

```python
intersection(left: Geometry, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None]) -> GeometryArray[Geometry | None]
```

```python
intersection(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None], right: Geometry) -> GeometryArray[Geometry | None]
```

```python
intersection(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None], right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT | None]) -> GeometryArray[Geometry | None]
```

```python
intersection(left: Geometry | GeometryArray[Geometry | None], right: Geometry | GeometryArray[Geometry | None]) -> Geometry | GeometryArray[Geometry | None]
```

Compute the set-theoretic intersection of `left` and `right`.

Evaluated in the coordinate plane. In a geographic CRS, topology resolves
longitude aliases, seam spellings, and pole longitudes in the CRS-native
frame; seam-crossing inputs are split into chart pieces before construction.
A closed axis-aligned rectangle containing the other operand's raw bounds
retains that operand verbatim when its bounds are sound in the operation's frame.

Parameters:

| Name | Type | Description | Default |
| --- | --- | --- | --- |
| `left` | `Geometry, GeometryArray, or iterable of Geometry or None` | Scalar and batch operands broadcast pairwise; batch lengths must match. Operands must share CRS and coordinate epoch. | *required* |
| `right` | `Geometry, GeometryArray, or iterable of Geometry or None` | Scalar and batch operands broadcast pairwise; batch lengths must match. Operands must share CRS and coordinate epoch. | *required* |

Returns:

| Type | Description |
| --- | --- |
| `Geometry or GeometryArray` | One result per input pair; missing rows remain missing. |

Raises:

| Type | Description |
| --- | --- |
| `CRSMismatchError` | If the operands' CRS or coordinate-epoch metadata differ. |
| `InvalidGeometryError` | If either operand has coordinates outside its geographic CRS domain. |
| `OverflowError` | If no adjacent binary64 assignment preserves the exact result topology. |
| `ResourceLimitError` | If the bounded embedding search is exhausted. |

Examples:

```pycon
>>> import gometry as gm
>>> left, right = gm.box(0, 0, 2, 2), gm.box(1, 1, 3, 3)
>>> gm.intersection(left, right).to_wkt()
'POLYGON ((1 1, 2 1, 2 2, 1 2, 1 1))'
```

## intersection\_all

Accepted call forms

```python
intersection_all(values: Point | MultiPoint | GeometryArray[Point | MultiPoint | None] | Iterable[Point | MultiPoint | None]) -> Point | MultiPoint
```

```python
intersection_all(values: Geometry | GeometryArray[Geometry | None] | Iterable[Geometry | Buffer | Mapping[str, Any] | SupportsGeoInterface | None]) -> Geometry
```

Common intersection of many geometries.

The region inside every input. When sound coordinate bounds prove operands
disjoint, returns the typed empty directly; in a geographic CRS this requires
every operand to be seam-free, pole-free, and canonically spelled. Otherwise,
the result is assembled from one joint arrangement. Mixed dimensions narrow
to the lowest shared dimension and an empty result keeps that dimension's
typed empty.

Parameters:

| Name | Type | Description | Default |
| --- | --- | --- | --- |
| `values` | `Geometry, GeometryArray, or iterable of Geometry` | One geometry or geometries to intersect. Missing array rows are skipped. | *required* |

Returns:

| Type | Description |
| --- | --- |
| `Geometry` | A single geometry that is the intersection of all inputs. |

Raises:

| Type | Description |
| --- | --- |
| `CRSMismatchError` | If the operands' CRS or coordinate-epoch metadata differ. |
| `OverflowError` | If no adjacent binary64 assignment preserves the exact result topology. |
| `ResourceLimitError` | If the bounded embedding search is exhausted. |
| `InvalidGeometryError` | If `values` is empty or contains coordinates outside its geographic CRS domain. |

See Also

[union\_all](https://gometry.monicz.dev/api/toplevel/overlay-dissolve/#gometry.union_all "union_all") : Union of many geometries into one.
[polygonize\_all](https://gometry.monicz.dev/api/toplevel/constructive-validation/#gometry.polygonize_all "polygonize_all") : Build polygons from pooled linework.

Examples:

```pycon
>>> import gometry as gm
>>> panes = [gm.box(0, 0, 3, 3), gm.box(1, 1, 4, 4), gm.box(2, 2, 5, 5)]
>>> gm.intersection_all(panes).to_wkt()
'POLYGON ((2 2, 3 2, 3 3, 2 3, 2 2))'
```

## symmetric\_difference

Accepted call forms

```python
symmetric_difference(left: Point | MultiPoint, right: Point | MultiPoint) -> Point | MultiPoint
```

```python
symmetric_difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | MultiPoint], right: Point | MultiPoint | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | MultiPoint]) -> GeometryArray[Point | MultiPoint]
```

```python
symmetric_difference(left: Point | MultiPoint, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | MultiPoint]) -> GeometryArray[Point | MultiPoint]
```

```python
symmetric_difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | MultiPoint | None], right: Point | MultiPoint | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | MultiPoint | None]) -> GeometryArray[Point | MultiPoint | None]
```

```python
symmetric_difference(left: Point | MultiPoint, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | MultiPoint | None]) -> GeometryArray[Point | MultiPoint | None]
```

```python
symmetric_difference(left: Geometry, right: Geometry) -> Geometry
```

```python
symmetric_difference(left: Geometry, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT]) -> GeometryArray[Geometry]
```

```python
symmetric_difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT], right: Geometry) -> GeometryArray[Geometry]
```

```python
symmetric_difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT], right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT]) -> GeometryArray[Geometry]
```

```python
symmetric_difference(left: Geometry, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None]) -> GeometryArray[Geometry | None]
```

```python
symmetric_difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None], right: Geometry) -> GeometryArray[Geometry | None]
```

```python
symmetric_difference(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None], right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT | None]) -> GeometryArray[Geometry | None]
```

```python
symmetric_difference(left: Geometry | GeometryArray[Geometry | None], right: Geometry | GeometryArray[Geometry | None]) -> Geometry | GeometryArray[Geometry | None]
```

Compute the set-theoretic symmetric difference of `left` and
`right`.

Evaluated in the coordinate plane. In a geographic CRS, topology resolves
longitude aliases, seam spellings, and pole longitudes in the CRS-native
frame; seam-crossing inputs are split into chart pieces before construction.

Parameters:

| Name | Type | Description | Default |
| --- | --- | --- | --- |
| `left` | `Geometry, GeometryArray, or iterable of Geometry or None` | Scalar and batch operands broadcast pairwise; batch lengths must match. Operands must share CRS and coordinate epoch. | *required* |
| `right` | `Geometry, GeometryArray, or iterable of Geometry or None` | Scalar and batch operands broadcast pairwise; batch lengths must match. Operands must share CRS and coordinate epoch. | *required* |

Returns:

| Type | Description |
| --- | --- |
| `Geometry or GeometryArray` | One result per input pair; missing rows remain missing. |

Raises:

| Type | Description |
| --- | --- |
| `CRSMismatchError` | If the operands' CRS or coordinate-epoch metadata differ. |
| `InvalidGeometryError` | If either operand has coordinates outside its geographic CRS domain. |
| `OverflowError` | If no adjacent binary64 assignment preserves the exact result topology. |
| `ResourceLimitError` | If the bounded embedding search is exhausted. |

Examples:

```pycon
>>> import gometry as gm
>>> left, right = gm.box(0, 0, 2, 1), gm.box(1, 0, 3, 1)
>>> gm.symmetric_difference(left, right).area
2.0
```

## symmetric\_difference\_all

Accepted call forms

```python
symmetric_difference_all(values: Point | MultiPoint | GeometryArray[Point | MultiPoint | None] | Iterable[Point | MultiPoint | None]) -> Point | MultiPoint
```

```python
symmetric_difference_all(values: Geometry | GeometryArray[Geometry | None] | Iterable[Geometry | Buffer | Mapping[str, Any] | SupportsGeoInterface | None]) -> Geometry
```

Symmetric difference of many geometries.

The region covered by an odd number of inputs. Strictly disjoint inputs are
assembled independently; inputs that can meet use one joint arrangement. In
a geographic CRS, topology resolves longitude aliases and seam and pole
equivalence in the native frame. The result is order-independent (`▵` is
associative and commutative).

Parameters:

| Name | Type | Description | Default |
| --- | --- | --- | --- |
| `values` | `Geometry, GeometryArray, or iterable of Geometry` | One geometry or geometries to combine. Missing array rows are skipped. | *required* |

Returns:

| Type | Description |
| --- | --- |
| `Geometry` | A single geometry covered by an odd number of inputs. |

Raises:

| Type | Description |
| --- | --- |
| `CRSMismatchError` | If the operands' CRS or coordinate-epoch metadata differ. |
| `OverflowError` | If no adjacent binary64 assignment preserves the exact result topology. |
| `ResourceLimitError` | If the bounded embedding search is exhausted. |
| `InvalidGeometryError` | If `values` is empty or contains coordinates outside its geographic CRS domain. |

Examples:

```pycon
>>> import gometry as gm
>>> panes = [gm.box(0, 0, 2, 2), gm.box(0, 0, 2, 2), gm.box(1, 1, 3, 3)]
>>> gm.symmetric_difference_all(panes).to_wkt()  # the duplicate cancels
'POLYGON ((1 1, 3 1, 3 3, 1 3, 1 1))'
```

## union

Accepted call forms

```python
union(left: Point | MultiPoint, right: Point | MultiPoint) -> Point | MultiPoint
```

```python
union(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | MultiPoint], right: Point | MultiPoint | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | MultiPoint]) -> GeometryArray[Point | MultiPoint]
```

```python
union(left: Point | MultiPoint, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | MultiPoint]) -> GeometryArray[Point | MultiPoint]
```

```python
union(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | MultiPoint | None], right: Point | MultiPoint | (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | MultiPoint | None]) -> GeometryArray[Point | MultiPoint | None]
```

```python
union(left: Point | MultiPoint, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[Point | MultiPoint | None]) -> GeometryArray[Point | MultiPoint | None]
```

```python
union(left: Geometry, right: Geometry) -> Geometry
```

```python
union(left: Geometry, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT]) -> GeometryArray[Geometry]
```

```python
union(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT], right: Geometry) -> GeometryArray[Geometry]
```

```python
union(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT], right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT]) -> GeometryArray[Geometry]
```

```python
union(left: Geometry, right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None]) -> GeometryArray[Geometry | None]
```

```python
union(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None], right: Geometry) -> GeometryArray[Geometry | None]
```

```python
union(left: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryT | None], right: (GeometryArray[GeometryRowT] | Iterable[GeometryRowT])[GeometryOtherT | None]) -> GeometryArray[Geometry | None]
```

```python
union(left: Geometry | GeometryArray[Geometry | None], right: Geometry | GeometryArray[Geometry | None]) -> Geometry | GeometryArray[Geometry | None]
```

Compute the set-theoretic union of `left` and `right`.

Evaluated in the coordinate plane. In a geographic CRS, topology resolves
longitude aliases, seam spellings, and pole longitudes in the CRS-native
frame; seam-crossing inputs are split into chart pieces before construction.

Parameters:

| Name | Type | Description | Default |
| --- | --- | --- | --- |
| `left` | `Geometry, GeometryArray, or iterable of Geometry or None` | Scalar and batch operands broadcast pairwise; batch lengths must match. Operands must share CRS and coordinate epoch. | *required* |
| `right` | `Geometry, GeometryArray, or iterable of Geometry or None` | Scalar and batch operands broadcast pairwise; batch lengths must match. Operands must share CRS and coordinate epoch. | *required* |

Returns:

| Type | Description |
| --- | --- |
| `Geometry or GeometryArray` | One result per input pair; missing rows remain missing. |

Raises:

| Type | Description |
| --- | --- |
| `CRSMismatchError` | If the operands' CRS or coordinate-epoch metadata differ. |
| `InvalidGeometryError` | If either operand has coordinates outside its geographic CRS domain. |
| `OverflowError` | If no adjacent binary64 assignment preserves the exact result topology. |
| `ResourceLimitError` | If the bounded embedding search is exhausted. |

See Also

[union\_all](https://gometry.monicz.dev/api/toplevel/overlay-dissolve/#gometry.union_all "union_all") : Union of many geometries at once.

Examples:

```pycon
>>> import gometry as gm
>>> gm.union(gm.box(0, 0, 1, 2), gm.box(1, 0, 2, 2)).to_wkt()
'POLYGON ((0 0, 2 0, 2 2, 0 2, 0 0))'
```

## union\_all

Accepted call forms

```python
union_all(values: Point | MultiPoint | GeometryArray[Point | MultiPoint | None] | Iterable[Point | MultiPoint | None]) -> Point | MultiPoint
```

```python
union_all(values: Geometry | GeometryArray[Geometry | None] | Iterable[Geometry | Buffer | Mapping[str, Any] | SupportsGeoInterface | None]) -> Geometry
```

Union of many geometries into one.

Strictly disjoint inputs are assembled independently; inputs that can meet
use one joint arrangement. In a geographic CRS, topology resolves longitude
aliases and seam and pole equivalence in the native frame.

Parameters:

| Name | Type | Description | Default |
| --- | --- | --- | --- |
| `values` | `Geometry, GeometryArray, or iterable of Geometry` | One geometry or geometries to union. Missing array rows are skipped. | *required* |

Returns:

| Type | Description |
| --- | --- |
| `Geometry` | A single geometry that is the union of all inputs. |

Raises:

| Type | Description |
| --- | --- |
| `CRSMismatchError` | If the operands' CRS or coordinate-epoch metadata differ. |
| `OverflowError` | If no adjacent binary64 assignment preserves the exact result topology. |
| `ResourceLimitError` | If the bounded embedding search is exhausted. |
| `InvalidGeometryError` | If `values` is empty or contains coordinates outside its geographic CRS domain. |

See Also

[coverage\_union\_all](https://gometry.monicz.dev/api/toplevel/coverage-polygonal/#gometry.coverage_union_all "coverage_union_all") : Faster dissolve for a valid polygonal coverage.
[intersection\_all](https://gometry.monicz.dev/api/toplevel/overlay-dissolve/#gometry.intersection_all "intersection_all") : Common region shared by many geometries.
[polygonize\_all](https://gometry.monicz.dev/api/toplevel/constructive-validation/#gometry.polygonize_all "polygonize_all") : Build polygons from pooled linework.

Examples:

```pycon
>>> import gometry as gm
>>> panes = [gm.box(0, 0, 2, 2), gm.box(1, 1, 3, 3)]
>>> gm.union_all(panes).to_wkt()
'POLYGON ((0 0, 2 0, 2 1, 3 1, 3 3, 1 3, 1 2, 0 2, 0 0))'
```