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我可以像这样绘制一些匀称的缓冲点：

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：

在此处输入图像描述

但是，如果我尝试使用底图绘制这些点，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()

在此处输入图像描述

我究竟做错了什么？

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1 回答 1

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It would help if you provided a working example, your image cannot be reproduced with the code you supplied.

If you plot with Basemap on a Mercator projected map, the coordinates you supply should be in the same projection. You are plotting WGS84 lat/lon on a Mercator projected map, thats not going to work. The buffer you apply to the points is also expressed in the map coordinates, which is meters instead of degrees.

The map object provides easy conversion with:

x,y = m(lon,lat)

So change your point creation to:

Point(m(lon, lat)).buffer(1000)
于 2013-09-04T10:22:44.733 回答