remove polygons with an intersection higher than a threshold

Question

The goal is to remove polygons with an intersection higher than a threshold, let’s say 80% of the area from the smaller intersected polygon.

In the following picture we see in first image how the small red circle in coordinate (2.06, 41.41) is overlapping with two big circles, in this case in a percentage higher than 80% of its area. So the output will be the second image where the polygons remains under an smaller area of intersection than 80%.

For a reproducible example the data from the image is:

df = pd.DataFrame({"centroid":[geometry.Point(2.1990512195822394, 41.390164933230444), 
                               geometry.Point(2.1253931941117, 41.39962167422747), 
                               geometry.Point(2.0894753122714187, 41.41858536477601), 
                               geometry.Point(2.0724937348578973, 41.41460885909822), 
                               geometry.Point(2.0617756309327735, 41.42279161424217)],
                   "radius":[591.0368301703261,
                             247.41971532239666,
                             1978.0374093864489,
                             270.9246060416432,
                             1218.9034814954907],
                  }
                 )

Asked By: PeCaDe

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Source

Answer 1

For computing the intersection area, just do the following:

import matplotlib.pyplot as plt
from shapely.geometry.point import Point

test_circle = Point(1.7, 3).buffer(0.5)
other = Point(3, 4).buffer(2)

intersection = other.intersection(test_circle)

plt.axis("equal")
plt.plot(*test_circle.exterior.xy, c="r")
plt.plot(*other.exterior.xy, c="g")

if intersection.area > 0.8 * test_circle.area:
    # do stuff
    ...

then you just have to test the possible combinations of overlapping circles.

Answered By: blunova

remove polygons with an intersection higher than a threshold

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