ee.Geometry.Polygon.difference

  • Returns a Geometry representing the portion of the 'left' geometry that does not intersect with the 'right' geometry.

  • Accepts a 'right' Geometry, an optional 'maxError' for reprojection, and an optional 'proj' for the operation's coordinate system.

  • Performs the difference operation in a spherical coordinate system with distances in meters on the sphere if no projection is specified.

  • Can be applied to Polygon geometries to calculate the geometric difference between them.

 Returns the result of subtracting the 'right' geometry from the 'left' geometry.

UsageReturns
Polygon.difference(right, maxError, proj)Geometry
ArgumentTypeDetails
this: leftGeometryThe geometry used as the left operand of the operation.
rightGeometryThe geometry used as the right operand of the operation.
maxErrorErrorMargin, default: nullThe maximum amount of error tolerated when performing any necessary reprojection.
projProjection, default: nullThe 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 Polygon object.
var polygon = ee.Geometry.Polygon(
    [[[-122.092, 37.424],
      [-122.086, 37.418],
      [-122.079, 37.425],
      [-122.085, 37.423]]]);

// Define other inputs.
var inputGeom = ee.Geometry.BBox(-122.085, 37.415, -122.075, 37.425);

// Apply the difference method to the Polygon object.
var polygonDifference = polygon.difference({'right': inputGeom, 'maxError': 1});

// Print the result to the console.
print('polygon.difference(...) =', polygonDifference);

// Display relevant geometries on the map.
Map.setCenter(-122.085, 37.422, 15);
Map.addLayer(polygon,
             {'color': 'black'},
             'Geometry [black]: polygon');
Map.addLayer(inputGeom,
             {'color': 'blue'},
             'Parameter [blue]: inputGeom');
Map.addLayer(polygonDifference,
             {'color': 'red'},
             'Result [red]: polygon.difference');

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 Polygon object.
polygon = ee.Geometry.Polygon([[
    [-122.092, 37.424],
    [-122.086, 37.418],
    [-122.079, 37.425],
    [-122.085, 37.423],
]])

# Define other inputs.
input_geom = ee.Geometry.BBox(-122.085, 37.415, -122.075, 37.425)

# Apply the difference method to the Polygon object.
polygon_difference = polygon.difference(right=input_geom, maxError=1)

# Print the result.
display('polygon.difference(...) =', polygon_difference)

# Display relevant geometries on the map.
m = geemap.Map()
m.set_center(-122.085, 37.422, 15)
m.add_layer(polygon, {'color': 'black'}, 'Geometry [black]: polygon')
m.add_layer(input_geom, {'color': 'blue'}, 'Parameter [blue]: input_geom')
m.add_layer(
    polygon_difference, {'color': 'red'}, 'Result [red]: polygon.difference'
)
m