diff --git a/lidar_pipeline/rendering.py b/lidar_pipeline/rendering.py
index b2b7864..86c07b8 100644
--- a/lidar_pipeline/rendering.py
+++ b/lidar_pipeline/rendering.py
@@ -261,7 +261,9 @@ def _apply_colormap(data, tif_file, resolution=None):
     if len(valid_data) == 0:
         return data, 'terrain', Path(tif_file).stem.replace('_', ' ').title(), '', '', False
     p2, p98 = np.percentile(valid_data, (2, 98))
-    data = np.clip((data - p2) / (p98 - p2), 0, 1)
+    # Garde contre les tuiles quasi constantes : plage nulle → division par zéro
+    span = max(p98 - p2, 1e-6)
+    data = np.clip((data - p2) / span, 0, 1)
     title = Path(tif_file).stem.replace('_', ' ').title()
     return data, 'terrain', title, 'Altitude normalisée', '', False