一组几何形状的信封-Geopandas

Question

要能够在Geopandas数据框架中对一组几何形状进行操作，我需要能够确定对象是否在集合的外部“边缘”上。几何形状集如下：

​我首先想到使用集合的凸壳：

convex_hull = Sectioned_geostore_obstacles_geometry.unary_union.convex_hull
convex_hull = geopandas.GeoDataFrame({'geometry': convex_hull, 'convex_hull':[1]})

ax = Sectioned_geostore_obstacles_geometry['Gondola'].plot(color='red')
convex_hull.plot(ax=ax, color='green', alpha=0.5)

它在

但这不是很正确，因为我正在寻找的不是凸。第二个想法是使用信封：

envelope = Sectioned_geostore_obstacles_geometry.unary_union.envelope
envelope = geopandas.GeoDataFrame({'geometry': envelope, 'convex_hull':[1]})

ax = Sectioned_geostore_obstacles_geometry['Gondola'].plot(color='red')
envelope.plot(ax=ax, color='green', alpha=0.5)

再次，不是。另一个尝试是使用Shapely的CASCADE_UNION功能：

from shapely.ops import cascaded_union
polygons = list(Sectioned_geostore_obstacles_geometry.Gondola)
boundary = gpd.GeoSeries(cascaded_union(polygons))

但是，这不是因为它返回了多角形而不是最小的eveloping polygon。 基本上，我需要信封才能缩小以遵循一组对象的轮廓。

任何见解都将不胜感激。

为了进行测试，我添加了以下示例数据：

test_df =  geopandas.GeoSeries([Polygon([(0,0), (2,0), (2,2), (0,2)]),
                              Polygon([(2,2), (4,2), (4,4), (2,4)])])
test_df = geopandas.GeoDataFrame({'geometry': test_df, 'df1':[1,2]})

convex_hull = test_df.unary_union.convex_hull
convex_hull = geopandas.GeoDataFrame({'geometry': convex_hull, 'convex_hull':[1]})

ax1 = test_df['geometry'].plot(color='red')
convex_hull.plot(ax=ax1, color='green', alpha=0.5)

envelope = test_df.unary_union.envelope
envelope = geopandas.GeoDataFrame({'geometry': envelope, 'convex_hull':[1]})

ax2 = test_df['geometry'].plot(color='red')
envelope.plot(ax=ax2, color='green', alpha=0.5)

Answer 1

通过确定一组几何形状的凹面壳：

https://gis.stackexchange.com/questions/4288882/minimal-preveding-polygon-to-set-to-set-of-geometries

/bera"> https://gis.stackexchange.com/users/32958/bera