Update graphical style (deprecate basemap, implement cartopy)

.github/workflows/pypi-publish.yaml

@@ -14,4 +14,4 @@ jobs:
         uses: JRubics/poetry-publish@v1.17
         with:
           pypi_token: ${{ secrets.PYPI_TOKEN }}
-          python_version: 3.9
+          python_version: 3.10

.github/workflows/tox.yaml

@@ -14,7 +14,7 @@ jobs:
 
     strategy:
       matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.10", "3.11", "3.12"]
       fail-fast: false
 
     steps:

README.md

@@ -8,7 +8,7 @@ A lightweight tool and Google Colab notebook for estimating the points on the Ea
 
 Using an object's height, the length of its shadow, the date and the time, ShadowFinder estimates the possible locations where that shadow could occur. These possible locations are shown as a bright band on a map of the Earth:
 
-![ExampleShadowFinderOutput](https://github.com/bellingcat/ShadowFinder/assets/54807169/391c9b54-d5b4-463f-9c09-94ff1fec6ee4)
+![ExampleShadowFinderOutput](https://github.com/user-attachments/assets/1620de90-3544-4678-856a-9ac5a56655a4)
 
 
 ## Usage - Google Colab Notebook 🚀

ShadowFinderColab.ipynb

@@ -14,9 +14,7 @@
     "\n",
     "Using an object's height and the length of its shadow (or the angle to the sun) with the date and the time, this code estimates the possible locations of that shadow.\n",
     "\n",
-    "> <font color='#ffc107'>Important:</font> The shadow length must be measured at right angles to the object 📐 This means that you might have to correct for the perspective of an image before using this tool.\n",
-    "\n",
-    "> <font color='#ab0107'>Bug Workaround:</font> At the moment there is a bug with Shadow Finder which results in an error. You can still use the tool in Google Colab by running the tool, getting the error, then restarting the session. Do this by navigating to the 'Runtime' menu at the top of the window, then click 'Restart session'. When you run the tool a second time it should work."
+    "> <font color='#ffc107'>Important:</font> The shadow length must be measured at right angles to the object 📐 This means that you might have to correct for the perspective of an image before using this tool.\n"
    ]
   },
   {

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "ShadowFinder"
-version = "0.5.0"
+version = "0.6.0"
 description = "Find possible locations of shadows."
 authors = ["Bellingcat"]
 license = "MIT License"
@@ -24,15 +24,15 @@ keywords=["shadow", "finder", "locator", "map"]
 shadowfinder = "shadowfinder.__main__:main"
 
 [tool.poetry.dependencies]
-python =  ">=3.9,<3.13"
+python =  ">=3.10,<3.13"
 matplotlib = "^3.8"
-basemap = "^1.4"
 suncalc = "^0.1.3"
 fire = "^0.5"
 timezonefinder = "^6.5"
 pandas = "^2.2"
-numpy = "^1"
+numpy = ">=1"
 pytz = "^2024.1"
+cartopy = "^0.24.1"
 
 [tool.poetry.group.dev.dependencies]
 black = "24.2.0"

src/shadowfinder/shadowfinder.py

@@ -4,10 +4,12 @@
 import numpy as np
 import matplotlib.pyplot as plt
 import matplotlib.colors as colors
-from mpl_toolkits.basemap import Basemap
+import cartopy.crs as ccrs
+import cartopy.feature as cfeature
+from cartopy.io import DownloadWarning
 from timezonefinder import TimezoneFinder
 import json
-from warnings import warn
+from warnings import warn, filterwarnings
 from math import radians
 
 
@@ -241,35 +243,54 @@ def find_shadows(self):
     def plot_shadows(
         self,
         figure_args={"figsize": (12, 6)},
-        basemap_args={"projection": "cyl", "resolution": "c"},
+        projection="PlateCarree",
+        projection_args={},
     ):
 
         fig = plt.figure(**figure_args)
 
-        # Add a simple map of the Earth
-        m = Basemap(**basemap_args)
-        m.drawcoastlines()
-        m.drawcountries()
+        # Set the a color scale and only show the values between 0 and 0.2
 
-        # Deal with the map projection
-        x, y = m(self.lons, self.lats)
+        # Create a custom LinearSegmented colormap
+        cmap = colors.LinearSegmentedColormap.from_list(
+            "custom_cmap",
+            [
+                # 0 is the peak likelihood, 1 is the low likelihood
+                (0, (1, 1, 0.75, 1)),  # Light Yellow - peak likelihood
+                (0.05, (1, 1, 0, 1)),  # Yellow - high likelihood
+                (0.2, (1, 0.5, 0, 1)),  # Orange - low likelihood
+                (1, (1, 0, 0, 0)),  # Transparent Red - no likelihood
+            ],
+            N=256,
+        )
+
+        # Override the edge value of the cmap
+        cmap.set_over("white", alpha=0.5)  # Day time colour
+        cmap.set_under("black", alpha=0.5)  # Night time colour
 
-        # Set the a color scale and only show the values between 0 and 0.2
-        cmap = plt.cm.get_cmap("inferno_r")
         norm = colors.BoundaryNorm(np.arange(0, 0.2, 0.02), cmap.N)
 
-        # Plot the data
-        m.pcolormesh(
-            x,
-            y,
-            np.abs(self.location_likelihoods),
+        # Create the map projection
+        filterwarnings("ignore", category=DownloadWarning)
+        ax = plt.axes(projection=getattr(ccrs, projection)(**projection_args))
+        ax.add_feature(cfeature.COASTLINE)
+        ax.add_feature(
+            cfeature.BORDERS, linestyle="-", edgecolor="black", linewidth=0.5
+        )
+
+        # replace NaN values with a specific value (e.g. -1)
+        surface = np.abs(self.location_likelihoods)
+        surface = np.where(np.isnan(surface), -1, surface)
+
+        ax.pcolormesh(
+            self.lons,
+            self.lats,
+            surface,
             cmap=cmap,
             norm=norm,
-            alpha=0.7,
+            transform=ccrs.PlateCarree(),
         )
 
-        # plt.colorbar(label='Relative Shadow Length Difference')
-
         if self.sun_altitude_angle is not None:
             plt_title = f"Possible Locations at {self.date_time.strftime('%Y-%m-%d %H:%M:%S')} {self.time_format.title()}\n(sun altitude angle: {self.sun_altitude_angle})"
         else:

tox.ini

@@ -1,8 +1,7 @@
 [tox]
-envlist = py39, py310, py311, py312
+envlist = py310, py311, py312
 labels =
     ; Used to map GitHub workflow python version to tox env
-    3.9 = py39
     3.10 = py310
     3.11 = py311
     3.12 = py312