diff --git a/GeoTools.cpp b/GeoTools.cpp
index d6e0ad5..d831f6d 100644
--- a/GeoTools.cpp
+++ b/GeoTools.cpp
@@ -38,6 +38,8 @@ AdjustId( int nId, int nCtx)
 Vector3d
 GetVectorLocal( IGeomDB* pGeomDB, const Vector3d& vtV, int nRefType, const Frame3d& frLoc)
 {
+   if ( ! vtV.IsValid())
+      return vtV ;
    Vector3d vtVL( vtV) ;
    if ( nRefType == RTY_GLOB)
       vtVL.ToLoc( frLoc) ;
@@ -50,6 +52,8 @@ GetVectorLocal( IGeomDB* pGeomDB, const Vector3d& vtV, int nRefType, const Frame
 Vector3d
 GetVectorInRef( IGeomDB* pGeomDB, const Vector3d& vtV, const Frame3d& frLoc, int nRefType)
 {
+   if ( ! vtV.IsValid())
+      return vtV ;
    Vector3d vtVL( vtV) ;
    if ( nRefType == RTY_GLOB)
       vtVL.ToGlob( frLoc) ;
@@ -62,6 +66,8 @@ GetVectorInRef( IGeomDB* pGeomDB, const Vector3d& vtV, const Frame3d& frLoc, int
 Point3d
 GetPointLocal( IGeomDB* pGeomDB, const Point3d& ptP, int nRefType, const Frame3d& frLoc)
 {
+   if ( ! ptP.IsValid())
+      return ptP ;
    Point3d ptPL( ptP) ;
    if ( nRefType == RTY_GLOB)
       ptPL.ToLoc( frLoc) ;
@@ -74,6 +80,8 @@ GetPointLocal( IGeomDB* pGeomDB, const Point3d& ptP, int nRefType, const Frame3d
 Point3d
 GetPointInRef( IGeomDB* pGeomDB, const Point3d& ptP, const Frame3d& frLoc, int nRefType)
 {
+   if ( ! ptP.IsValid())
+      return ptP ;
    Point3d ptPL( ptP) ;
    if ( nRefType == RTY_GLOB)
       ptPL.ToGlob( frLoc) ;
diff --git a/LUA_GdbCreateSurf.cpp b/LUA_GdbCreateSurf.cpp
index 1fa9578..a5e0957 100644
--- a/LUA_GdbCreateSurf.cpp
+++ b/LUA_GdbCreateSurf.cpp
@@ -805,7 +805,7 @@ LuaCreateSurfTmSwept( lua_State* L)
    int nGuideId ;
    LuaCheckParam( L, 3, nGuideId)
    int nPar = 4 ;
-   Vector3d vtAx = V_NULL ;
+   Vector3d vtAx = V_INVALID ;
    if ( LuaGetParam( L, nPar, vtAx))
       ++ nPar ;
    bool bCapEnds ;