diff --git a/SurfBezier.cpp b/SurfBezier.cpp
index f0c2378..c8ae0a3 100644
--- a/SurfBezier.cpp
+++ b/SurfBezier.cpp
@@ -738,7 +738,8 @@ SurfBezier::Load( NgeReader& ngeIn)
       }
    }
   // se trimmata, lettura della regione
-   if ( m_bTrimmed) {
+   if ( bTrimmed) {
+      m_bTrimmed = true ;
      // creo l'oggetto
       ResetTrimRegion() ;
       m_pTrimReg = CreateBasicSurfFlatRegion() ;
@@ -746,7 +747,7 @@ SurfBezier::Load( NgeReader& ngeIn)
          return false ;
      // ne leggo i dati
       IGeoObjRW* pGObjRW = dynamic_cast<IGeoObjRW*>( m_pTrimReg) ;
-      if ( pGObjRW == nullptr  ||  pGObjRW->Load( ngeIn))
+      if ( pGObjRW == nullptr  ||  ! pGObjRW->Load( ngeIn))
          return false ;
    }
 
@@ -1029,11 +1030,13 @@ SurfBezier::Invert( void)
    }
    m_vPtCtrl = vPtCtrl_inv ;
 
-  // inverto la flat region di trim
-  //( la specchio rispetto all'asse verticale)
-   Point3d pt( m_nSpanU * SBZ_TREG_COEFF/2, 0, 0) ;
-   Vector3d vt( 1, 0, 0) ;
-   m_pTrimReg->Mirror( pt, vt) ;
+   if ( m_bTrimmed) {
+     // inverto la flat region di trim
+     //( la specchio rispetto all'asse verticale)
+      Point3d pt( m_nSpanU * SBZ_TREG_COEFF/2, 0, 0) ;
+      Vector3d vt( 1, 0, 0) ;
+      m_pTrimReg->Mirror( pt, vt) ;
+   }
 
    return true ;
 }
@@ -1569,7 +1572,7 @@ SurfBezier::GetLeaves( std::vector<std::tuple<int, Point3d, Point3d>>& vLeaves)
       Tree.SetSurf( this, true, ptMin, ptMax) ;
       //Tree.BuildTree_test() ;
       //Tree.BuildTree( 5 * LIN_TOL_FINE, 1) ;
-      Tree.BuildTree( LIN_TOL_FINE, 0.1) ;
+      Tree.BuildTree( 5 * LIN_TOL_FINE, 0.1) ;
       Tree.GetLeaves( vCells) ;
       for (int k = 0 ; k < (int)vCells.size(); ++ k ) {
          std::tuple<int, Point3d, Point3d> tCell ;
diff --git a/Tree.cpp b/Tree.cpp
index c78e447..dcb91f3 100644
--- a/Tree.cpp
+++ b/Tree.cpp
@@ -305,8 +305,8 @@ Tree::SetSurf( const SurfBezier* pSrfBz, const bool bSplitPatches, const Point3d
                Split( 1) ;
             }
          }
-         // se ho fatto solo 1 split e ho due celle foglie nId = 0 e nId = 1
-         else if ( (int) m_mTree.size() > 1  && (int) m_mTree.size() < 4) { // si può mettere anche < 5
+         // se ho fatto solo 1 split orizzontale e ho due celle foglie nId = 0 e nId = 1
+         else if ( (int) m_mTree.size() > 1  && (int) m_mTree.size() < 4  &&  ! m_mTree.at(-1).IsSplitVert()) { // si può mettere anche < 5
             m_mTree[0].m_nLeft = -1 ;
             m_mTree[0].m_nRight = -1 ;
             m_mTree[1].m_nLeft = -1 ;