diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..de02313
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,24 @@
+# Python # 
+*.py[cod] 
+*$py.class 
+
+# Distribution / packaging 
+.Python build/ 
+develop-eggs/ 
+dist/ 
+downloads/ 
+eggs/ 
+.eggs/ 
+lib/ 
+lib64/ 
+parts/ 
+sdist/ 
+var/ 
+wheels/ 
+*.whl
+*.egg-info/ 
+.installed.cfg 
+*.egg 
+*.manifest 
+*.spec 
+
diff --git a/docs/cli/hillshade.rst b/docs/cli/hillshade.rst
index b1eb4a7..7823539 100644
--- a/docs/cli/hillshade.rst
+++ b/docs/cli/hillshade.rst
@@ -11,7 +11,7 @@ computes the shadows of the ground surface (buildings, trees, etc.).
 
   $ rastertools hillshade --help
   usage: rastertools hillshade [-h] --elevation ELEVATION --azimuth AZIMUTH
-                               [--radius RADIUS] --resolution RESOLUTION 
+                               [--radius RADIUS] --resolution RESOLUTION
                                [-o OUTPUT] [-ws WINDOW_SIZE]
                                [-p {none,edge,maximum,mean,median,minimum,reflect,symmetric,wrap}]
                                inputs [inputs ...]
diff --git a/src/eolab/rastertools/cli/__init__.py b/src/eolab/rastertools/cli/__init__.py
index 38c658f..50cf82d 100644
--- a/src/eolab/rastertools/cli/__init__.py
+++ b/src/eolab/rastertools/cli/__init__.py
@@ -69,4 +69,4 @@ def with_bands_arguments(parser):
         '--all',
         dest="all_bands",
         action="store_true",
-        help="Compute all bands")
+        help="Compute all bands")
\ No newline at end of file
diff --git a/src/eolab/rastertools/hillshade.py b/src/eolab/rastertools/hillshade.py
index 6eaadb4..900816d 100644
--- a/src/eolab/rastertools/hillshade.py
+++ b/src/eolab/rastertools/hillshade.py
@@ -105,27 +105,31 @@ def process_file(self, inputfile: str) -> List[str]:
         outdir = Path(self.outputdir)
         output_image = outdir.joinpath(f"{utils.get_basename(inputfile)}-hillshade.tif")
 
-        if self.radius is None:
-            # compute the radius from data range
-            # radius represents the max distance of buildings that can create a hillshade
-            # considering the sun elevation.
-            wmax = None
-            wmin = None
-            with rasterio.open(inputfile) as src:
-                if src.count != 1:
-                    raise ValueError("Invalid input file, it must contain a single band.")
-                for ji, window in src.block_windows(1):
-                    data = src.read(1, masked=True, window=window)
-                    wmax = max(wmax, float(data.max())) if wmax is not None else float(data.max())
-                    wmin = min(wmin, float(data.min())) if wmin is not None else float(data.min())
-
-            delta = int((wmax - wmin) / self.resolution)
-            radius = int(delta / np.tan(np.radians(self.elevation)))
+        # compute the radius from data range
+        # radius represents the max distance of buildings that can create a hillshade
+        # considering the sun elevation.
+        wmax = None
+        wmin = None
+        with rasterio.open(inputfile) as src:
+            if src.count != 1:
+                raise ValueError("Invalid input file, it must contain a single band.")
+            for ji, window in src.block_windows(1):
+                data = src.read(1, masked=True, window=window)
+                wmax = max(wmax, float(data.max())) if wmax is not None else float(data.max())
+                wmin = min(wmin, float(data.min())) if wmin is not None else float(data.min())
+
+        delta = int((wmax - wmin) / self.resolution)
+        optimal_radius = int(delta / np.tan(np.radians(self.elevation)))
+
+        if self.radius is None or optimal_radius <= self.radius:
+            self.radius = optimal_radius
         else:
-            radius = self.radius
+            _logger.warning(f"The optimal radius value is {optimal_radius} exceeding {self.radius} threshold. "
+                            f"Oversized radius affects computation time and so radius is set to {self.radius}. "
+                            "Result may miss some shadow pixels.")
 
-        if radius >= min(self.window_size) / 2:
-            raise ValueError(f"The radius (option --radius, value={radius}) must be strictly "
+        if self.radius >= min(self.window_size) / 2:
+            raise ValueError(f"The radius (option --radius, value={self.radius}) must be strictly "
                              "less than half the size of the window (option --window_size, "
                              f"value={min(self.window_size)})")
 
@@ -143,7 +147,7 @@ def process_file(self, inputfile: str) -> List[str]:
             "elevation": self.elevation,
             "azimuth": self.azimuth,
             "resolution": self.resolution,
-            "radius": radius
+            "radius": self.radius
         }
         hillshade.configure(hillshade_conf)
 
@@ -151,7 +155,7 @@ def process_file(self, inputfile: str) -> List[str]:
         compute_sliding(
             inputfile, output_image, hillshade,
             window_size=self.window_size,
-            window_overlap=radius,
+            window_overlap=self.radius,
             pad_mode=self.pad_mode)
 
         return [output_image.as_posix()]