python - Python：具有简单解决方案的多边形 shapefile 中的轮廓特征

Question

尊敬的会员名单，

首先，我很抱歉发布这个从以前的帖子修改和改进的问题。最近我正在研究 shapefiles 多边形以计算基本轮廓特征：

1. 区域，
2. 周长，
3. 面积凸包，
4. 周边凸包，
5. 主轴长度 = 给出主轴的长度，
6. 短轴长度 = 给出短轴的长度，

其中长轴和短轴长度是根据下图计算的：

使用 osgeo.gdal、ogr 和 shapely可以加载和计算所有索引，但不能加载和计算长轴和短轴长度。在线阅读解决方案可以使用

1. scikit-image = 测量区域属性
2. 开放式CV

我正在寻找一个简单的解决方案，以使我的代码简单而优雅。一些博客建议对我的多边形进行椭圆近似，以检索长轴和短轴长度。这是最好的解决方案吗？

任何参考资料都会很有帮助。提前致谢

---

import osgeo.gdal, ogr
from shapely.geometry import Polygon

shp = osgeo.ogr.Open('../examples/mypoly.shp')
layer = shp.GetLayer()
feature = layer.GetFeature(0)
geometry = feature.GetGeometryRef()
# get area
Area = geometry.GetArea()
pts = geometry.GetGeometryRef(0)
points = []
for p in range(pts.GetPointCount()):
   points.append((pts.GetX(p), pts.GetY(p)))
polygon = Polygon(points)
# get Perimeter
Perimeter = polygon.length
# convex Hull
ConvexHull = polygon.convex_hull
# get Perimeter convex Hull
PerimeterConvexHull = ConvexHull.length
# get Area convex Hull
AreaConvexHull = ConvexHull.area

这些是我的多边形的坐标顶点

polygon = Polygon([(560023.4495758876400000 6362057.3904932579000000),(560023.4495758876400000 6362060.3904932579000000),(560024.4495758876400000 6362063.3904932579000000),(560026.9495758876400000 6362068.3904932579000000),(560028.4495758876400000 6362069.8904932579000000),(560034.9495758876400000 6362071.8904932579000000),(560036.4495758876400000 6362071.8904932579000000),(560037.4495758876400000 6362070.3904932579000000),(560037.4495758876400000 6362064.8904932579000000),(560036.4495758876400000 6362063.3904932579000000),(560034.9495758876400000 6362061.3904932579000000),(560026.9495758876400000 6362057.8904932579000000),(560025.4495758876400000 6362057.3904932579000000),(560023.4495758876400000 6362057.3904932579000000)])

为了从这里测试我的代码：

polygon = Polygon(points)
# get Perimeter
Perimeter = polygon.length
# convex Hull
ConvexHull = polygon.convex_hull
# get Perimeter convex Hull
PerimeterConvexHull = ConvexHull.length
# get Area convex Hull
AreaConvexHull = ConvexHull.area

Answer 1

嗨，我有一些关于 shapefile 多边形的工作，喜欢你的工作。我使用 minimum_rotated_rectangle 来定义majoraxis_length和minoraxis_length。我的代码是：

polygon = Polygon(points)  
ConvexHull = polygon.convex_hull  #  convex Hull
#minimum_ rotated_ Rectangle is the minimum boundary rectangle, exterior is the external point coordinates of the minimum boundary matrix, and coords is the coordinates of the points
p1 = Point(ConvexHull.minimum_rotated_rectangle.exterior.coords[0])
p2 = Point(ConvexHull.minimum_rotated_rectangle.exterior.coords[1])
p3 = Point(ConvexHull.minimum_rotated_rectangle.exterior.coords[2])
majoraxis_length  =  p1.distance(p2)
minoraxis_length = p2.distance(p3)