限制正交投影的范围（缩放）

Question

我想生成关于默认设置 'zoomed' 的南极洲正交（极地）图。默认情况下我得到这个：

下面的脚本产生了这个。

import cartopy.crs as ccrs
import matplotlib.pyplot as plt

ax = plt.axes(projection=ccrs.Orthographic(central_longitude=0.0, central_latitude=-90.))
ax.stock_img()
plt.show()

我告诉 Cartopy 'limit the latitude to 60S to 90S' 的最佳尝试是：

ax.set_extent([-180,180,-60,-90], ccrs.PlateCarree())

不幸的是它没有给出desired result。有任何想法吗？提前致谢。

Answer 1

我不确定我是否完全理解您的意图。您的示例看起来像一个已定义的边界框，但您希望它像您的第一个示例一样圆润？

cartopy 文档有一个这样的例子 http://scitools.org.uk/cartopy/docs/latest/examples/always_circular_stereo.html:

 import matplotlib.path as mpath
 import matplotlib.pyplot as plt
 import numpy as np

 import cartopy.crs as ccrs
 import cartopy.feature


 def main():
     fig = plt.figure(figsize=[10, 5])
     ax1 = plt.subplot(1, 2, 1, projection=ccrs.SouthPolarStereo())
     ax2 = plt.subplot(1, 2, 2, projection=ccrs.SouthPolarStereo(),
                       sharex=ax1, sharey=ax1)
     fig.subplots_adjust(bottom=0.05, top=0.95,
                         left=0.04, right=0.95, wspace=0.02)

     # Limit the map to -60 degrees latitude and below.
     ax1.set_extent([-180, 180, -90, -60], ccrs.PlateCarree())

     ax1.add_feature(cartopy.feature.LAND)
     ax1.add_feature(cartopy.feature.OCEAN)

     ax1.gridlines()
     ax2.gridlines()

     ax2.add_feature(cartopy.feature.LAND)
     ax2.add_feature(cartopy.feature.OCEAN)

     # Compute a circle in axes coordinates, which we can use as a boundary
     # for the map. We can pan/zoom as much as we like - the boundary will be
     # permanently circular.
     theta = np.linspace(0, 2*np.pi, 100)
     center, radius = [0.5, 0.5], 0.5
     verts = np.vstack([np.sin(theta), np.cos(theta)]).T
     circle = mpath.Path(verts * radius + center)

     ax2.set_boundary(circle, transform=ax2.transAxes)

     plt.show()

 if __name__ == '__main__':
     main()

限制正交投影的范围（缩放）

Limit extent of orthograpic projection (zooming)

cartopy