Readapted the non-open3d code

utils/surfaces.py

@@ -20,7 +20,7 @@ except ImportError:
     print('could not import VTK functions')
     gotVTK = False
 
-
+eps = 1e-8
 # import kernelFunctions as kfun
 
 class vtkFields:
@@ -198,7 +198,7 @@ class Surface:
             normals[F[k, 2]] += self.surfel[k]
         af = np.sqrt((normals ** 2).sum(axis=1))
         # logging.info('min area = %.4f'%(af.min()))
-        normals /= af.reshape([self.vertices.shape[0], 1])
+        normals /= (af.reshape([self.vertices.shape[0], 1]) + eps)
 
         return normals