Announcement: On November 13, 2024, all users will need to use a Cloud project in order to access Earth Engine. After this date, continued individual access without a Cloud project will require an exception.

ee.Geometry.MultiPolygon.convexHull

Returns the convex hull of the given geometry. The convex hull of a single point is the point itself, the convex hull of collinear points is a line, and the convex hull of everything else is a polygon. Note that a degenerate polygon with all vertices on the same line will result in a line segment.

Usage	Returns
`MultiPolygon.convexHull(maxError, proj)`	Geometry

Argument	Type	Details
this: `geometry`	Geometry	Calculates the convex hull of this geometry.
`maxError`	ErrorMargin, default: null	The maximum amount of error tolerated when performing any necessary reprojection.
`proj`	Projection, default: null	The projection in which to perform the operation. If not specified, the operation will be performed in a spherical coordinate system, and linear distances will be in meters on the sphere.

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 convexHull method to the MultiPolygon object.
var multiPolygonConvexHull = multiPolygon.convexHull({'maxError': 1});

// Print the result to the console.
print('multiPolygon.convexHull(...) =', multiPolygonConvexHull);

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

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 convexHull method to the MultiPolygon object.
multipolygon_convex_hull = multipolygon.convexHull(maxError=1)

# Print the result.
display('multipolygon.convexHull(...) =', multipolygon_convex_hull)

# 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_convex_hull,
    {'color': 'red'},
    'Result [red]: multipolygon.convexHull',
)
m