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| import os |
| import hashlib |
| import contextily as ctx |
| from mpl_toolkits.basemap import Basemap |
| import cartopy.crs as ccrs |
| import cartopy.feature as cfeature |
| from PIL import Image |
| import matplotlib.pyplot as plt |
|
|
| |
| |
| os.environ["XDG_CACHE_HOME"] = os.path.expanduser("~/.contextily_cache") |
|
|
| CTX_TILE_CACHE_DIR = os.path.expanduser("~/.contextily_cache") |
| BASEMAP_TILE_CACHE_DIR = os.path.expanduser("~/.basemap_cache") |
|
|
| os.makedirs(CTX_TILE_CACHE_DIR, exist_ok=True) |
| os.makedirs(BASEMAP_TILE_CACHE_DIR, exist_ok=True) |
|
|
| def draw_etopo_basemap(ax, mode="basemap", zoom=11): |
| """ |
| Draws a high-resolution basemap background on the provided Cartopy GeoAxes. |
| |
| Parameters |
| ---------- |
| ax : matplotlib.axes._subplots.AxesSubplot |
| The matplotlib Axes object (with Cartopy projection) to draw the map background on. |
| |
| mode : str, optional |
| The basemap mode to use: |
| - "stock": Default stock image from Cartopy. |
| - "contextily": Web tile background (CartoDB Voyager), with caching. |
| - "basemap": High-resolution shaded relief using Basemap, with caching. |
| Default is "basemap". |
| |
| zoom : int, optional |
| Tile zoom level (only for "contextily"). Higher = more detail. Default is 7. |
| |
| Notes |
| ----- |
| - Uses high resolution for Basemap (resolution='h') and saves figure at 300 DPI. |
| - Cached images are reused using extent-based hashing to avoid re-rendering. |
| - Basemap is deprecated; Cartopy with web tiles is recommended for new projects. |
| """ |
| try: |
| if mode == "stock": |
| ax.stock_img() |
|
|
| elif mode == "contextily": |
| extent = ax.get_extent(crs=ccrs.PlateCarree()) |
| ax.set_extent(extent, crs=ccrs.PlateCarree()) |
| ctx.add_basemap( |
| ax, |
| crs=ccrs.PlateCarree(), |
| source=ctx.providers.CartoDB.Voyager, |
| zoom=zoom |
| ) |
|
|
| elif mode == "basemap": |
| extent = ax.get_extent(crs=ccrs.PlateCarree()) |
|
|
| |
| extent_str = f"{extent[0]:.4f}_{extent[1]:.4f}_{extent[2]:.4f}_{extent[3]:.4f}" |
| cache_key = hashlib.md5(extent_str.encode()).hexdigest() |
| cache_file = os.path.join(BASEMAP_TILE_CACHE_DIR, f"{cache_key}_highres.png") |
|
|
| if os.path.exists(cache_file): |
| img = Image.open(cache_file) |
| ax.imshow(img, extent=extent, transform=ccrs.PlateCarree()) |
| else: |
| |
| temp_fig, temp_ax = plt.subplots(figsize=(12, 9), |
| subplot_kw={'projection': ccrs.PlateCarree()}) |
| temp_ax.set_extent(extent, crs=ccrs.PlateCarree()) |
|
|
| m = Basemap(projection='cyl', |
| llcrnrlon=extent[0], urcrnrlon=extent[1], |
| llcrnrlat=extent[2], urcrnrlat=extent[3], |
| resolution='f', ax=temp_ax) |
|
|
| m.shadedrelief() |
| |
| |
| |
|
|
| |
| temp_fig.savefig(cache_file, dpi=300, bbox_inches='tight', pad_inches=0) |
| plt.close(temp_fig) |
|
|
| |
| img = Image.open(cache_file) |
| ax.imshow(img, extent=extent, transform=ccrs.PlateCarree()) |
|
|
| else: |
| raise ValueError(f"Unsupported basemap mode: {mode}") |
|
|
| except Exception as e: |
| print(f"[Relief Error - {mode} mode]:", e) |
| ax.add_feature(cfeature.LAND) |
| ax.add_feature(cfeature.OCEAN) |
|
|
