Repository: SciTools/cartopy

Issue:
the resolution of cartopy land is too coarse
### Description
<!-- Please provide a general introduction to the issue/proposal. -->
using cartopy, the coarse resolution of land can not be improved even the scale is "10m". see the figure, the land and islands are so close. How to solve this problem？
![image](https://user-images.githubusercontent.com/16815156/140031061-beacd601-8e32-40d2-a846-c585b691b238.jpeg)

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#### Code to reproduce

```
import matplotlib.pyplot as plt
    import cartopy
    
    def spatdistriClass():
    
        size = 10
        plt.rc('font', family='Times New Roman', weight='normal', size=size)
        font = {'family': 'Times New Roman',
                'color': 'black',
                'weight': 'normal',
                'size': size}
    
        pro = cartopy.crs.PlateCarree()
        fig, axes_arr = plt.subplots(nrows=1, ncols=1, figsize=(5.5, 3.3),
                                     subplot_kw={'projection': cartopy.crs.PlateCarree(central_longitude=180)})
        ax1 = axes_arr
        ax1.coastlines('10m', color="grey", linewidth=0.1)
        ax1.add_feature(cartopy.feature.LAND.with_scale('10m'), facecolor='grey')
    
        plt.savefig("image.jpeg", dpi=300, bbox_inches='tight', pad_inches=0.01)
        plt.show()
        plt.close()
        return " "
    
    
    if __name__ == '__main__':
        spatdistriClass() 

```

#### Traceback 

```

```

<details>
 <summary>Full environment definition</summary>

<!-- fill in the following information as appropriate -->

### Operating system


### Cartopy version


### conda list

```
```

### pip list

```
```

</details>



Discussion:
If you specify `edgecolor='none'` I think you'll get what you're looking for.

Perhaps that should actually be the default for these filled polygons... I'm not sure why they have the edgecolor explicitly set to 'face'.
https://github.com/SciTools/cartopy/blob/313f02f3e90309277209eca65b8b211256a527d5/lib/cartopy/feature/__init__.py#L500-L503

Resolving patch:
diff --git a/lib/cartopy/feature/__init__.py b/lib/cartopy/feature/__init__.py
--- a/lib/cartopy/feature/__init__.py
+++ b/lib/cartopy/feature/__init__.py
@@ -493,19 +493,19 @@ def intersecting_geometries(self, extent):
 
 LAKES = NaturalEarthFeature(
     'physical', 'lakes', auto_scaler,
-    edgecolor='face', facecolor=COLORS['water'])
+    edgecolor='none', facecolor=COLORS['water'])
 """Automatically scaled natural and artificial lakes."""
 
 
 LAND = NaturalEarthFeature(
     'physical', 'land', auto_scaler,
-    edgecolor='face', facecolor=COLORS['land'], zorder=-1)
+    edgecolor='none', facecolor=COLORS['land'], zorder=-1)
 """Automatically scaled land polygons, including major islands."""
 
 
 OCEAN = NaturalEarthFeature(
     'physical', 'ocean', auto_scaler,
-    edgecolor='face', facecolor=COLORS['water'], zorder=-1)
+    edgecolor='none', facecolor=COLORS['water'], zorder=-1)
 """Automatically scaled ocean polygons."""
 
 


Test patch:
diff --git a/lib/cartopy/tests/mpl/test_features.py b/lib/cartopy/tests/mpl/test_features.py
--- a/lib/cartopy/tests/mpl/test_features.py
+++ b/lib/cartopy/tests/mpl/test_features.py
@@ -17,11 +17,16 @@
 @pytest.mark.mpl_image_compare(filename='natural_earth.png')
 def test_natural_earth():
     ax = plt.axes(projection=ccrs.PlateCarree())
-    ax.add_feature(cfeature.LAND)
-    ax.add_feature(cfeature.OCEAN)
+    # NOTE: edgecolor is set to face for backwards compatibility with the
+    #       the original image. If updating this test remove edgecolors for
+    #       the filled features below (LAND, OCEAN, LAKES).
+    ec = 'face'
+    ax.add_feature(cfeature.LAND, edgecolor=ec)
+    # To match with the old default style and not update an image
+    ax.add_feature(cfeature.OCEAN, edgecolor=ec)
     ax.coastlines()
     ax.add_feature(cfeature.BORDERS, linestyle=':')
-    ax.add_feature(cfeature.LAKES, alpha=0.5)
+    ax.add_feature(cfeature.LAKES, alpha=0.5, edgecolor=ec)
     ax.add_feature(cfeature.RIVERS)
     ax.set_xlim((-20, 60))
     ax.set_ylim((-40, 40))