diff --git a/CurveAux.cpp b/CurveAux.cpp
index 3adb9f2..bf755c1 100644
--- a/CurveAux.cpp
+++ b/CurveAux.cpp
@@ -295,7 +295,7 @@ CurveGetAreaXY( const ICurve& crvC, double& dArea)
       return false ;
   // approssimo la curva con una polilinea
    PolyLine PL ;
-   crvC.ApproxWithLines( LIN_TOL_STD, ANG_TOL_STD_DEG, ICurve::APL_STD, PL) ;
+   crvC.ApproxWithLines( LIN_TOL_STD, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, PL) ;
   // calcolo l'area
    double dAreaXY = 0 ;
    PL.GetAreaXY( dAreaXY) ;
@@ -314,7 +314,7 @@ CurveGetArea( const ICurve& crvC, Plane3d& plPlane, double& dArea)
       return false ;
   // approssimo la curva con una polilinea
    PolyLine PL ;
-   crvC.ApproxWithLines( LIN_TOL_STD, ANG_TOL_STD_DEG, ICurve::APL_STD, PL) ;
+   crvC.ApproxWithLines( LIN_TOL_STD, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, PL) ;
   // calcolo l'area
    Plane3d plMyPlane ;
    double dMyArea = 0 ;
diff --git a/CurveComposite.cpp b/CurveComposite.cpp
index 5b66bfe..9bf10ad 100644
--- a/CurveComposite.cpp
+++ b/CurveComposite.cpp
@@ -957,7 +957,7 @@ CurveComposite::GetCentroid( Point3d& ptCen) const
       return false ;
   // approssimo la curva con una polilinea
    PolyLine PL ;
-   if ( ! ApproxWithLines( LIN_TOL_STD, ANG_TOL_STD_DEG, ICurve::APL_STD, PL))
+   if ( ! ApproxWithLines( LIN_TOL_STD, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, PL))
       return false ;
   // calcolo il centro mediante PolygonPlane
    Point3d ptP ;
@@ -1255,15 +1255,39 @@ CurveComposite::ApproxWithLines( double dLinTol, double dAngTolDeg, int nType, P
    dLinTol = max( dLinTol, LIN_TOL_MIN) ;
    dAngTolDeg = max( dAngTolDeg, ANG_TOL_MIN_DEG) ;
 
-  // se lineare con lato obbligato, gestione speciale
+  // se speciale, approssimo ogni singola entitā e conservo le estremitā interne (joint)
+   if ( nType == APL_SPECIAL) {
+     // eseguo approssimazione
+      double dStartPar = 0 ;
+      for ( auto& pCrv : m_CrvSmplS) {
+        // assegno estrusione e spessore della curva composita
+         pCrv->SetExtrusion( m_VtExtr) ;
+         pCrv->SetThickness( m_dThick) ;
+        // recupero approssimazione per curva semplice
+         PolyLine PLSmpl ;
+         if ( ! pCrv->ApproxWithLines( dLinTol, dAngTolDeg, nType, PLSmpl))
+            return false ;
+        // ripristino estrusione e spessore della curva semplice (annullandoli)
+         pCrv->SetExtrusion( V_NULL) ;
+         pCrv->SetThickness( 0) ;
+        // la accodo opportunamente a quella della curva composita
+         if ( ! PL.Join( PLSmpl, dStartPar))
+            return false ;
+        // incremento inizio parametro per prossima curva semplice
+         dStartPar += 1 ;
+      }
+      return true ;
+   }
+
+  // se lineare con lato obbligato...
    if ( nType == APL_LEFT  ||  nType == APL_LEFT_CONVEX  ||
         nType == APL_RIGHT  ||  nType == APL_RIGHT_CONVEX) {
-     // prima approssimazione lineare  a 10 * Epsilon
-      if ( ! ApproxWithLines( 10 * EPS_SMALL, dAngTolDeg, APL_STD, PL))
+     // prima approssimazione lineare a 10 * Epsilon
+      if ( ! ApproxWithLines( 10 * EPS_SMALL, dAngTolDeg, APL_SPECIAL, PL))
          return false ;
      // eliminazione dei punti in tolleranza andando solo dalla parte ammessa
       Vector3d vtExtr = ( m_VtExtr.IsSmall() ? Z_AX : m_VtExtr) ;
-      if ( ! PL.ApproxOnSide( vtExtr, ( nType == APL_LEFT), dLinTol))
+      if ( ! PL.ApproxOnSide( vtExtr, ( nType == APL_LEFT  ||  nType == APL_LEFT_CONVEX), dLinTol))
          return false ;
      // se necessario, sistemo per convessitā dalla parte ammessa
       if ( nType == APL_RIGHT_CONVEX  ||  nType == APL_LEFT_CONVEX) {
@@ -1273,27 +1297,12 @@ CurveComposite::ApproxWithLines( double dLinTol, double dAngTolDeg, int nType, P
       return true ;
    }
 
-  // eseguo approssimazione
-   double dStartPar = 0 ;
-   for ( auto& pCrv : m_CrvSmplS) {
-     // assegno estrusione e spessore della curva composita
-      pCrv->SetExtrusion( m_VtExtr) ;
-      pCrv->SetThickness( m_dThick) ;
-     // recupero approssimazione per curva semplice
-      PolyLine PLSmpl ;
-      if ( ! pCrv->ApproxWithLines( dLinTol, dAngTolDeg, nType, PLSmpl))
-         return false ;
-     // ripristino estrusione e spessore della curva semplice (annullandoli)
-      pCrv->SetExtrusion( V_NULL) ;
-      pCrv->SetThickness( 0) ;
-     // la accodo opportunamente a quella della curva composita
-      if ( ! PL.Join( PLSmpl, dStartPar))
-         return false ;
-     // incremento inizio parametro per prossima curva semplice
-      dStartPar += 1 ;
-   }
- 
-   return true ;
+  // altrimenti standard
+   // prima approssimazione lineare a 10 * Epsilon di ogni singola entitā
+   if ( ! ApproxWithLines( 10 * EPS_SMALL, dAngTolDeg, APL_SPECIAL, PL))
+      return false ;
+   // eliminazione dei punti in tolleranza
+   return PL.RemoveAlignedPoints( dLinTol) ;
 }
 
 //----------------------------------------------------------------------------
diff --git a/EgtGeomKernel.rc b/EgtGeomKernel.rc
index ed529c4..fca4212 100644
Binary files a/EgtGeomKernel.rc and b/EgtGeomKernel.rc differ
diff --git a/IntersCurveCurve.cpp b/IntersCurveCurve.cpp
index 089a18a..6614430 100644
--- a/IntersCurveCurve.cpp
+++ b/IntersCurveCurve.cpp
@@ -52,7 +52,7 @@ IntersCurveCurve::IntersCurveCurve( const ICurve& CurveA, const ICurve& CurveB,
            m_pCurve[i]->GetType() == CRV_BEZ) {
         // approssimo con rette
          PolyLine PL ;
-         if ( ! m_pCurve[i]->ApproxWithLines( EPS_SMALL, ANG_TOL_STD_DEG, ICurve::APL_STD, PL))
+         if ( ! m_pCurve[i]->ApproxWithLines( EPS_SMALL, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, PL))
             return ;
          pTmpCrv[i].Set( CreateBasicCurveComposite()) ;
          if ( IsNull( pTmpCrv[i]))
@@ -635,7 +635,7 @@ bool
 IntersCurveCurve::GetCurveOutClass( const ICurve* pCurve, int& nClass)
 {
    PolyLine PL ;
-   if ( ! pCurve->ApproxWithLines( LIN_TOL_APPROX, ANG_TOL_APPROX_DEG, ICurve::APL_STD, PL))
+   if ( ! pCurve->ApproxWithLines( LIN_TOL_APPROX, ANG_TOL_APPROX_DEG, ICurve::APL_SPECIAL, PL))
       return false ;
    double dArea ;
    if ( ! PL.GetAreaXY( dArea))
diff --git a/OutTsc.cpp b/OutTsc.cpp
index 4a5f41e..4941432 100644
--- a/OutTsc.cpp
+++ b/OutTsc.cpp
@@ -478,7 +478,7 @@ OutTsc::PutCurve( const ICurve* pCurve, int nFlag)
    Point3d  ptIni ;
    Point3d  ptFin ;
    PolyLine PL ;
-   pCurve->ApproxWithLines( 0.1, 5, ICurve::APL_STD, PL) ;
+   pCurve->ApproxWithLines( 0.1, 5, ICurve::APL_SPECIAL, PL) ;
    for ( bool bFound = PL.GetFirstLine( ptIni, ptFin) ; bFound ; bFound = PL.GetNextLine( ptIni, ptFin))
       Line2P( ptIni, ptFin) ;
 
diff --git a/PolyLine.cpp b/PolyLine.cpp
index 0a8098e..63af6b2 100644
--- a/PolyLine.cpp
+++ b/PolyLine.cpp
@@ -18,6 +18,7 @@
 #include "IntersLineLine.h"
 #include "PolygonPlane.h"
 #include "PointsPCA.h"
+#include "GeoConst.h"
 #include "/EgtDev/Include/EGkPolyLine.h"
 #include "/EgtDev/Include/EGkPlane3d.h"
 #include "/EgtDev/Include/EGnStringUtils.h"
@@ -670,8 +671,10 @@ PolyLine::RemoveAlignedPoints( double dToler)
   // se non ci sono almeno 3 punti, esco subito
    if ( m_lUPoints.size() < 3)
       return true ;
+  // controllo minimo valore di tolleranza
+   dToler = max( dToler, LIN_TOL_MIN) ;
   // coefficiente deduzione tolleranza
-   const double COEFF_TOL = 0.7 ;
+   const double COEFF_TOL = 0.90 ;
   // si analizza la distanza di un punto dal segmento che unisce precente e successivo
   // punto precedente
    auto precP = m_lUPoints.begin() ;
diff --git a/SelfIntersCurve.cpp b/SelfIntersCurve.cpp
index 64fb839..880741b 100644
--- a/SelfIntersCurve.cpp
+++ b/SelfIntersCurve.cpp
@@ -49,7 +49,7 @@ SelfIntersCurve::SelfIntersCurve( const ICurve& Curve)
         m_pCurve->GetType() == CRV_BEZ) {
      // approssimo con rette
       PolyLine PL ;
-      if ( ! m_pCurve->ApproxWithLines( EPS_SMALL, ANG_TOL_STD_DEG, ICurve::APL_STD, PL))
+      if ( ! m_pCurve->ApproxWithLines( EPS_SMALL, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, PL))
          return ;
       pTmpCrv.Set( CreateBasicCurveComposite()) ;
       if ( IsNull( pTmpCrv))
diff --git a/StmFromCurves.cpp b/StmFromCurves.cpp
index 634ec8b..c56451a 100644
--- a/StmFromCurves.cpp
+++ b/StmFromCurves.cpp
@@ -33,7 +33,7 @@ GetSurfTriMeshByFlatContour( const ICurve* pCurve, double dLinTol)
       return nullptr ;
   // calcolo la polilinea che approssima la curva
    PolyLine PL ;
-   if ( ! pCurve->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_STD, PL))
+   if ( ! pCurve->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, PL))
       return nullptr ;
   // creo e setto la superficie trimesh
    PtrOwner<ISurfTriMesh> pSTM( CreateSurfTriMesh()) ;
@@ -77,7 +77,7 @@ GetSurfTriMeshByExtrusion( const ICurve* pCurve, const Vector3d& vtExtr,
       return nullptr ;
   // calcolo la polilinea che approssima la curva
    PolyLine PL ;
-   if ( ! pCurve->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_STD, PL))
+   if ( ! pCurve->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, PL))
       return nullptr ;
   // se richiesta chiusura agli estremi
    bool bDoCapEnds = false ;
@@ -196,7 +196,7 @@ GetSurfTriMeshByRevolve( const ICurve* pCurve, const Point3d& ptAx, const Vector
    dLinTol = max( dLinTol, EPS_SMALL) ;
   // calcolo la polilinea che approssima la curva
    PolyLine PL ;
-   if ( ! pCurve->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_STD, PL))
+   if ( ! pCurve->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, PL))
       return nullptr ;
   // calcolo lo step di rotazione
    double dMaxRad = 0 ;
@@ -259,7 +259,7 @@ GetSurfTriMeshByScrewing( const ICurve* pCurve, const Point3d& ptAx, const Vecto
    dLinTol = max( dLinTol, EPS_SMALL) ;
   // calcolo la polilinea che approssima la curva
    PolyLine PL ;
-   if ( ! pCurve->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_STD, PL))
+   if ( ! pCurve->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, PL))
       return nullptr ;
   // calcolo lo step di rotazione
    double dMaxRad = 0 ;
@@ -291,7 +291,7 @@ GetSurfTriMeshRuled( const Point3d& ptP, const ICurve* pCurve, double dLinTol)
       return nullptr ;
   // calcolo la polilinea che approssima la curva
    PolyLine PL ;
-   if ( ! pCurve->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_STD, PL))
+   if ( ! pCurve->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, PL))
       return nullptr ;
   // creo e setto la superficie trimesh
    PtrOwner<ISurfTriMesh> pSTM( CreateSurfTriMesh()) ;
@@ -312,11 +312,11 @@ GetSurfTriMeshRuled( const ICurve* pCurve1, const ICurve* pCurve2, double dLinTo
       return nullptr ;
   // calcolo la polilinea che approssima la prima curva
    PolyLine PL1 ;
-   if ( ! pCurve1->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_STD, PL1))
+   if ( ! pCurve1->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, PL1))
       return nullptr ;
   // calcolo la polilinea che approssima la seconda curva
    PolyLine PL2 ;
-   if ( ! pCurve2->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_STD, PL2))
+   if ( ! pCurve2->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, PL2))
       return nullptr ;
   // creo e setto la superficie trimesh
    PtrOwner<ISurfTriMesh> pSTM( CreateSurfTriMesh()) ;
@@ -337,7 +337,7 @@ CalcRegionPolyLines( const CICURVEPVECTOR& vpCurve, double dLinTol,
    POLYLINEVECTOR vPLtmp ;
    vPLtmp.resize( vpCurve.size()) ;
    for ( int i = 0 ; i < int( vpCurve.size()) ; ++ i) {
-      if ( ! vpCurve[i]->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_STD, vPLtmp[i]))
+      if ( ! vpCurve[i]->ApproxWithLines( dLinTol, ANG_TOL_STD_DEG, ICurve::APL_SPECIAL, vPLtmp[i]))
          return nullptr ;
    }
   // ne calcolo l'area e genero un ordine in senso decrescente