diff --git a/IntersPlaneSurfTm.cpp b/IntersPlaneSurfTm.cpp
index e4b6c7f..dfdfc5c 100644
--- a/IntersPlaneSurfTm.cpp
+++ b/IntersPlaneSurfTm.cpp
@@ -257,7 +257,7 @@ IntersParPlanesSurfTm::IntersParPlanesSurfTm( const Frame3d& frPlanes, const ISu
 
 //----------------------------------------------------------------------------
 bool
-IntersParPlanesSurfTm::GetInters( const Point3d& ptPl, PNTVECTOR& vPnt, BIPNTVECTOR& vBpt, TRIA3DVECTOR& vTria) const
+IntersParPlanesSurfTm::GetInters( double dDist, PNTVECTOR& vPnt, BIPNTVECTOR& vBpt, TRIA3DVECTOR& vTria) const
 {
   // verifico validità
    if ( ! m_bOk)
@@ -283,14 +283,13 @@ IntersParPlanesSurfTm::GetInters( const Point3d& ptPl, PNTVECTOR& vPnt, BIPNTVEC
    TrGrid.SetActivationGrid( true) ;
 
   // calcolo il piano ( in globale)
+   Point3d ptPl = m_frPlanes.Orig() + dDist * m_frPlanes.VersZ() ;
    Plane3d plPlane ;
    plPlane.Set( ptPl, m_frPlanes.VersZ()) ;
 
   // calcolo box del piano ( nel riferimento)
-   Point3d ptL = ptPl ;
-   ptL.ToLoc( m_frPlanes) ;
    BBox3d b3Plane ;
-   b3Plane.Add( ptL) ;
+   b3Plane.Add( Point3d( 0, 0, dDist)) ;
    b3Plane.Expand( INFINITO - 1 , INFINITO - 1, 0) ;
 
   // recupero indici triangoli che intersecano box