ee.Geometry.MultiPolygon.dissolve

AI-generated Key Takeaways

• The dissolve method returns the union of a geometry, leaving single geometries untouched and unioning multi geometries.

• The dissolve method can accept optional maxError and proj arguments to control the error tolerance and projection used for the union operation.

• Examples are provided in both JavaScript and Python to demonstrate how to use the dissolve method and visualize the results on a map.

Returns the union of the geometry. This leaves single geometries untouched, and unions multi geometries.

Usage	Returns
MultiPolygon.dissolve(maxError, proj)	Geometry

Argument	Type	Details
this: geometry	Geometry	The geometry to union.
maxError	ErrorMargin, default: null	The maximum amount of error tolerated when performing any necessary reprojection.
proj	Projection, default: null	If specified, the union will be performed in this projection. Otherwise it will be performed in a spherical coordinate system.

Examples

Code Editor (JavaScript)

// Define a MultiPolygon object.
var multiPolygon = ee.Geometry.MultiPolygon(
    [[[[-122.092, 37.424],
       [-122.086, 37.418],
       [-122.079, 37.425],
       [-122.085, 37.423]]],
     [[[-122.081, 37.417],
       [-122.086, 37.421],
       [-122.089, 37.416]]]]);

// Apply the dissolve method to the MultiPolygon object.
var multiPolygonDissolve = multiPolygon.dissolve({'maxError': 1});

// Print the result to the console.
print('multiPolygon.dissolve(...) =', multiPolygonDissolve);

// Display relevant geometries on the map.
Map.setCenter(-122.085, 37.422, 15);
Map.addLayer(multiPolygon,
             {'color': 'black'},
             'Geometry [black]: multiPolygon');
Map.addLayer(multiPolygonDissolve,
             {'color': 'red'},
             'Result [red]: multiPolygon.dissolve');

Python setup

See the Python Environment page for information on the Python API and using geemap for interactive development.

import ee
import geemap.core as geemap

Colab (Python)

# Define a MultiPolygon object.
multipolygon = ee.Geometry.MultiPolygon([
    [[
        [-122.092, 37.424],
        [-122.086, 37.418],
        [-122.079, 37.425],
        [-122.085, 37.423],
    ]],
    [[[-122.081, 37.417], [-122.086, 37.421], [-122.089, 37.416]]],
])

# Apply the dissolve method to the MultiPolygon object.
multipolygon_dissolve = multipolygon.dissolve(maxError=1)

# Print the result.
display('multipolygon.dissolve(...) =', multipolygon_dissolve)

# Display relevant geometries on the map.
m = geemap.Map()
m.set_center(-122.085, 37.422, 15)
m.add_layer(
    multipolygon, {'color': 'black'}, 'Geometry [black]: multipolygon'
)
m.add_layer(
    multipolygon_dissolve,
    {'color': 'red'},
    'Result [red]: multipolygon.dissolve',
)
m