使用底图和descart的绘图不显示PolygonPatch

Question

我可以绘制一些Shapely缓冲点，如下所示：

import matplotlib.pyplot as plt
from matplotlib.collections import PatchCollection
from mpl_toolkits.basemap import Basemap
from shapely.geometry import Point
from descartes import PolygonPatch

fig = plt.figure()
ax = fig.add_subplot(111)
minx, miny, maxx, maxy = [-6.108398, 49.61071, 1.669922, 58.972667]
w, h = maxx - minx, maxy - miny
x, y = (-0.117588, 51.513230)
correct = Point(x, y).buffer(0.5)
ax.add_patch(PolygonPatch(correct, fc='#cc00cc', ec='#555555', alpha=0.5, zorder=5))
ax.set_xlim(minx - 0.2 * w, maxx + 0.2 * w)
ax.set_ylim(miny - 0.2 * h, maxy + 0.2 * h)
ax.set_aspect(1)
ax.add_patch(patch)
plt.show()

这导致以下情节：

但是，如果我尝试使用Basemap绘制这些点，则它们不会出现：

bounds = [-6.108398, 49.61071, 1.669922, 58.972667]
minx, miny, maxx, maxy = bounds
w, h = maxx - minx, maxy - miny
fig = plt.figure()
ax = fig.add_subplot(111)
m = Basemap(
    projection='merc',
    ellps = 'WGS84',
    llcrnrlon=minx - 0.2 * w,
    llcrnrlat=miny - 0.2 * h,
    urcrnrlon=maxx + 0.2 * w,
    urcrnrlat=maxy + 0.2 * h,
    lat_ts=0,
    resolution='i')
m.drawcoastlines()
m.drawmapboundary()
# set axes limits to map crs
min_x, min_y = m(minx, miny)
max_x, max_y = m(maxx, maxy)
corr_w, corr_h = max_x - min_x, max_y - min_y
ax.set_xlim(min_x - 0.2 * corr_w, max_x + 0.2 * corr_w)
ax.set_ylim(min_y - 0.2 * corr_h, max_y + 0.2 * corr_h)
ax.set_aspect(1)
# add known good coordinate
x, y = m(-0.117588, 51.513230)
correct = Point(x, y).buffer(1.)
ax.add_patch(PolygonPatch(correct, fc='#cc00cc', ec='#555555', alpha=0.5, zorder=5))

plt.show()

我做错了什么？

Answer 1

如果你提供了一个有效的例子，那么你的图像就无法用你提供的代码重现。

如果您在墨卡托投影地图上使用底图进行绘图，则您提供的坐标应位于同一投影中。您正在墨卡托投影地图上绘制WGS84纬度/经度，这不会起作用。应用于点的缓冲区也以地图坐标表示，即米而不是度。

地图对象提供了简单的转换：

x,y = m(lon,lat)

所以将你的创造点改为：

Point(m(lon, lat)).buffer(1000)