diff --git a/CurveArc.cpp b/CurveArc.cpp
index 027528f..93d3af7 100644
--- a/CurveArc.cpp
+++ b/CurveArc.cpp
@@ -895,7 +895,7 @@ CurveArc::GetParamAtLength( double dLen, double& dU) const
       return false ;
 
   // fine
-   if ( dLen < dTotLen - EPS_SMALL) {
+   if ( dLen > dTotLen - EPS_SMALL) {
       dU = 1 ;
       return true ;
    }
diff --git a/CurveBezier.cpp b/CurveBezier.cpp
index 049e111..4bd4a64 100644
--- a/CurveBezier.cpp
+++ b/CurveBezier.cpp
@@ -597,11 +597,29 @@ CurveBezier::GetMidPoint( Point3d& ptMid) const
   // verifico lo stato
    if ( m_nStatus != OK)
       return false ;
-                          
+  // determino il valore del parametro a metà lunghezza
+   double dLen, dMid ;
+   if ( ! GetLength( dLen)  ||  ! GetParamAtLength( 0.5 * dLen, dMid))
+      return false ;      
   // calcolo il punto
-   return GetPointD1D2( 0.5, ptMid) ;
+   return GetPointD1D2( dMid, ptMid) ;
 } 
 
+//----------------------------------------------------------------------------
+bool
+CurveBezier::GetMidDir( Vector3d& vtDir) const
+{
+  // verifico lo stato
+   if ( m_nStatus != OK)
+      return false ;
+  // determino il valore del parametro a metà lunghezza
+   double dLen, dMid ;
+   if ( ! GetLength( dLen)  ||  ! GetParamAtLength( 0.5 * dLen, dMid))
+      return false ;      
+  // calcolo la direzione
+   return ::GetTang( *this, dMid, FROM_MINUS, vtDir) ;
+}
+
 //----------------------------------------------------------------------------
 bool
 CurveBezier::GetPointD1D2( double dU, Side nS, Point3d& ptPos, Vector3d* pvtDer1, Vector3d* pvtDer2) const
@@ -1177,8 +1195,10 @@ CurveBezier::GetParamAtLength( double dLen, double& dU) const
    double dCurrLen = 0 ;
    double dUIni = 0 ;
    double dUFin = 1 ;
-   while ( ( bOk = GetSegmentParam( dLen, dCurrLen, dSegLen, dUIni, dUFin))  &&  dSegLen > MIN_SEG_LEN)
-      ;
+   while ( ( bOk = GetSegmentParam( dLen, dCurrLen, dSegLen, dUIni, dUFin))  &&  dSegLen > MIN_SEG_LEN) {
+     // allungo di un poco l'intervallo di ricerca per compensare l'approssimazione della lunghezza
+      dUFin = min( dUFin + ( dUFin - dUIni) * 0.05, 1) ;
+   }
   // aggiustamento finale parametro
    if ( bOk)
       dU = dUIni + ( dLen - dCurrLen) / dSegLen * ( dUFin - dUIni) ;
diff --git a/CurveBezier.h b/CurveBezier.h
index a5d0b27..648e3ec 100644
--- a/CurveBezier.h
+++ b/CurveBezier.h
@@ -66,8 +66,7 @@ class CurveBezier : public ICurveBezier, public IGeoObjRW
                       { return ::GetTang( *this, 0, FROM_PLUS, vtDir) ; }
       virtual bool GetEndDir( Vector3d& vtDir) const
                       { return ::GetTang( *this, 1, FROM_MINUS, vtDir) ; }
-      virtual bool GetMidDir( Vector3d& vtDir) const
-                      { return ::GetTang( *this, 0.5, FROM_MINUS, vtDir) ; }
+      virtual bool GetMidDir( Vector3d& vtDir) const ;
       virtual bool GetExtrusion( Vector3d& vtExtr) const
                       { vtExtr = m_VtExtr ; return ( m_nStatus == OK) ; }
       virtual bool GetThickness( double& dThick) const
diff --git a/CurveComposite.cpp b/CurveComposite.cpp
index 4c35f4c..271f52c 100644
--- a/CurveComposite.cpp
+++ b/CurveComposite.cpp
@@ -869,16 +869,29 @@ CurveComposite::GetMidPoint( Point3d& ptMid) const
   // verifico lo stato
    if ( m_nStatus != OK)
       return false ;
-             
-  // determino il valore medio del parametro della curva
-   double dStart, dEnd, dMid ;
-   GetDomain( dStart, dEnd) ;
-   dMid = 0.5 * ( dStart + dEnd) ;
-                          
+  // determino il valore del parametro a metà lunghezza
+   double dLen, dMid ;
+   if ( ! GetLength( dLen)  ||  ! GetParamAtLength( 0.5 * dLen, dMid))
+      return false ;      
   // calcolo il punto
    return GetPointD1D2( dMid, FROM_MINUS, ptMid) ;
 } 
 
+//----------------------------------------------------------------------------
+bool
+CurveComposite::GetMidDir( Vector3d& vtDir) const
+{
+  // verifico lo stato
+   if ( m_nStatus != OK)
+      return false ;
+  // determino il valore del parametro a metà lunghezza
+   double dLen, dMid ;
+   if ( ! GetLength( dLen)  ||  ! GetParamAtLength( 0.5 * dLen, dMid))
+      return false ;
+  // calcolo la direzione         
+   return ::GetTang( *this, 0.5 * m_nCounter, FROM_MINUS, vtDir) ;
+}
+
 //----------------------------------------------------------------------------
 bool
 CurveComposite::GetDomain( double& dStart, double& dEnd) const
@@ -1064,7 +1077,7 @@ CurveComposite::GetParamAtLength( double dLen, double& dU) const
       }
    }
 
-   return false ;
+   return true ;
 }
 
 //----------------------------------------------------------------------------
diff --git a/CurveComposite.h b/CurveComposite.h
index 201243d..b460148 100644
--- a/CurveComposite.h
+++ b/CurveComposite.h
@@ -66,8 +66,7 @@ class CurveComposite : public ICurveComposite, public IGeoObjRW
                       { return ::GetTang( *this, 0, FROM_PLUS, vtDir) ; }
       virtual bool GetEndDir( Vector3d& vtDir) const
                       { return ::GetTang( *this, m_nCounter, FROM_MINUS, vtDir) ; }
-      virtual bool GetMidDir( Vector3d& vtDir) const
-                      { return ::GetTang( *this, 0.5 * m_nCounter, FROM_MINUS, vtDir) ; }
+      virtual bool GetMidDir( Vector3d& vtDir) const ;
       virtual bool GetExtrusion( Vector3d& vtExtr) const
                       { vtExtr = m_VtExtr ; return ( m_nStatus == OK) ; }
       virtual bool GetThickness( double& dThick) const
diff --git a/CurveLine.cpp b/CurveLine.cpp
index 4e85af0..72831e5 100644
--- a/CurveLine.cpp
+++ b/CurveLine.cpp
@@ -424,7 +424,7 @@ CurveLine::GetParamAtLength( double dLen, double& dU) const
       return false ;
 
   // fine
-   if ( dLen < dTotLen - EPS_SMALL) {
+   if ( dLen > dTotLen - EPS_SMALL) {
       dU = 1 ;
       return true ;
    }
diff --git a/EgtGeomKernel.rc b/EgtGeomKernel.rc
index 3340ff6..d411907 100644
Binary files a/EgtGeomKernel.rc and b/EgtGeomKernel.rc differ