diff --git a/VolZmapGraphics.cpp b/VolZmapGraphics.cpp
index 7f66c45..5dc1c13 100644
--- a/VolZmapGraphics.cpp
+++ b/VolZmapGraphics.cpp
@@ -292,6 +292,21 @@ CreateBigTriangleYZ( double dMinY, double dMaxY, double dMinZ, double dMaxZ, dou
    return trTria1.Validate( true)  &&  trTria2.Validate( true)  ;       
 }
 
+//----------------------------------------------------------------------------
+double
+GetFanTotalNormalDeviation( Point3d ptP, AppliedVector Vector[7], int nVertNum)
+{
+   double dSum = 0 ;
+   for ( int m = 0 ; m < nVertNum ; ++ m) {
+      int l = ( m + 1) % nVertNum ;
+      Vector3d vtNlm = ( Vector[l].ptPApp - ptP) ^ ( Vector[m].ptPApp - ptP) ;
+      vtNlm.Normalize() ;
+      dSum += vtNlm * Vector[l].vtVec ;
+      dSum += vtNlm * Vector[m].vtVec ;
+   }
+   return dSum ;
+}
+
 //----------------------------------------------------------------------------
 bool
 VolZmap::FindAdjComp( const vector<VoxelContainer>& vVecVox, int nCurBlock, int nCurVox, int nCurComp,
@@ -1998,6 +2013,20 @@ VolZmap::ExtMarchingCubes( int nBlock, VoxelContainer& vVox) const
                   bool bExtConfirmed = true ;
                   Vector3d vtNullSpace( dMatrixV( 0, 2), dMatrixV( 1, 2), dMatrixV( 2, 2)) ;
                   if ( nFeatureType == EDGE  &&  vtNullSpace.Normalize()  &&  ! IsPointInsideVoxelApprox( i, j, k, ptSol)) {
+                     double dBestDisp = 0 ;
+                     double dMaxVal = - DBL_MAX ;
+                     double dDisplH = 0.1 * m_dStep ;
+                     double dDispStop = 0.5 * m_dStep ;
+                     double dDisp = - 0.5 * m_dStep;
+                     while ( dDisp < dDispStop + EPS_SMALL) {
+                        double dCrVal = GetFanTotalNormalDeviation( ptSol + dDisp * vtNullSpace, CompoVert[nComp], nVertComp[nComp]) ;
+                        if ( dCrVal > dMaxVal) {
+                           dMaxVal = dCrVal ;
+                           dBestDisp = dDisp ;
+                        }
+                        dDisp += dDisplH ;
+                     }
+                     ptSol += dBestDisp * vtNullSpace ;
                      int nNewAdjVoxIJK[3] ;
                      if ( GetPointVoxel( ptSol, nNewAdjVoxIJK[0], nNewAdjVoxIJK[1], nNewAdjVoxIJK[2])) {
                         int nNewAdjVoxIndex = CalcIndex( nNewAdjVoxIJK[0], nNewAdjVoxIJK[1], nNewAdjVoxIJK[2]) ;