Changing var names

qim3d/processing/features.py

 import numpy as np
+import qim3d.processing
 from qim3d.utils.logger import log
 import trimesh
 import qim3d
 
+
 def volume(obj, **mesh_kwargs) -> float:
     """
     Compute the volume of a 3D volume or mesh.
@@ -44,7 +46,8 @@ def volume(obj, **mesh_kwargs) -> float:
         log.info("Converting volume to mesh.")
         obj = qim3d.processing.create_mesh(obj, **mesh_kwargs)
 
-    return obj.volume
+    return abs(obj.volume)
+
 
 def area(obj, **mesh_kwargs) -> float:
     """
@@ -88,6 +91,7 @@ def area(obj, **mesh_kwargs) -> float:
 
     return obj.area
 
+
 def sphericity(obj, **mesh_kwargs) -> float:
     """
     Compute the sphericity of a 3D volume or mesh.
@@ -135,13 +139,13 @@ def sphericity(obj, **mesh_kwargs) -> float:
         log.info("Converting volume to mesh.")
         obj = qim3d.processing.create_mesh(obj, **mesh_kwargs)
 
-    V = volume(obj)
-    A = area(obj)
+    volume = qim3d.processing.volume(obj)
+    area = qim3d.processing.area(obj)
 
-    if A == 0:
+    if area == 0:
         log.warning("Surface area is zero, sphericity is undefined.")
         return np.nan
 
-    sphericity = (np.pi**(1/3) * (6 * V)**(2/3)) / A
+    sphericity = (np.pi ** (1 / 3) * (6 * volume) ** (2 / 3)) / area
     log.info(f"Sphericity: {sphericity}")
     return sphericity