diff --git a/libsrc/occ/occ_face.cpp b/libsrc/occ/occ_face.cpp
index 7b985f06..032ace63 100644
--- a/libsrc/occ/occ_face.cpp
+++ b/libsrc/occ/occ_face.cpp
@@ -12,7 +12,7 @@ namespace netgen
         : tface(dshape.TShape()),
           face(TopoDS::Face(dshape))
     {
-        BRepGProp::LinearProperties(face, props);
+        BRepGProp::SurfaceProperties (dshape, props);
         bbox = ::netgen::GetBoundingBox(face);
 
         surface = BRep_Tool::Surface(face);
diff --git a/libsrc/occ/occ_utils.cpp b/libsrc/occ/occ_utils.cpp
index 210e358e..5f36d357 100644
--- a/libsrc/occ/occ_utils.cpp
+++ b/libsrc/occ/occ_utils.cpp
@@ -27,6 +27,22 @@ namespace netgen
         return trafo;
     }
 
+  Transformation<3> occ2ng (const gp_GTrsf & occ_trafo)
+    {
+        Transformation<3> trafo;
+        auto v = occ_trafo.TranslationPart();
+        auto m = occ_trafo.VectorialPart();
+        auto & tv = trafo.GetVector();
+        auto & tm = trafo.GetMatrix();
+        for(auto i : Range(3))
+        {
+            tv[i] = v.Coord(i+1);
+            for(auto k : Range(3))
+                tm(i,k) = m(i+1,k+1);
+        }
+        return trafo;
+    }
+
     Box<3> GetBoundingBox( const TopoDS_Shape & shape )
     {
         Bnd_Box bb;
diff --git a/libsrc/occ/occ_utils.hpp b/libsrc/occ/occ_utils.hpp
index e51a2b51..85ae0ad1 100644
--- a/libsrc/occ/occ_utils.hpp
+++ b/libsrc/occ/occ_utils.hpp
@@ -1,6 +1,8 @@
 #ifndef FILE_OCC_UTILS_INCLUDED
 #define FILE_OCC_UTILS_INCLUDED
 
+#include <variant>
+
 #include <BRepGProp.hxx>
 #include <BRep_Tool.hxx>
 #include <GProp_GProps.hxx>
@@ -10,6 +12,7 @@
 #include <TopoDS.hxx>
 #include <TopoDS_Vertex.hxx>
 #include <gp_Trsf.hxx>
+#include <gp_GTrsf.hxx>
 
 #include "meshing.hpp"
 
@@ -49,6 +52,13 @@ namespace netgen
     }
 
     DLL_HEADER Transformation<3> occ2ng (const gp_Trsf & t);
+    DLL_HEADER Transformation<3> occ2ng (const gp_GTrsf & t);
+    inline Transformation<3> occ2ng (const variant<gp_Trsf, gp_GTrsf> & t)
+    {
+      if(auto t1 = get_if<gp_Trsf>(&t))
+        return occ2ng(*t1);
+      return occ2ng(get<gp_GTrsf>(t));
+    }
 
     inline gp_Pnt ng2occ (const Point<3> & p)
     {
diff --git a/libsrc/occ/occgeom.cpp b/libsrc/occ/occgeom.cpp
index 3d36bb7a..a163baf3 100644
--- a/libsrc/occ/occgeom.cpp
+++ b/libsrc/occ/occgeom.cpp
@@ -1955,13 +1955,6 @@ namespace netgen
       return false;
    }
 
-  Point<3> GetCenter(const TopoDS_Shape & shape)
-  {
-      GProp_GProps props;
-      BRepGProp::LinearProperties(shape, props);
-      return occ2ng( props.CentreOfMass() );
-  }
-
   bool IsMappedShape(const Transformation<3> & trafo, const TopoDS_Shape & me, const TopoDS_Shape & you)
   {
       if(me.ShapeType() != you.ShapeType()) return false;
@@ -1971,8 +1964,8 @@ namespace netgen
       BRepBndLib::Add(you, bbox);
       BoxTree<3> tree( occ2ng(bbox.CornerMin()), occ2ng(bbox.CornerMax()) );
 
-      Point<3> c_me = GetCenter(me);
-      Point<3> c_you = GetCenter(you);
+      Point<3> c_me = occ2ng(Center(me));
+      Point<3> c_you = occ2ng(Center(you));
       if(tree.GetTolerance() < Dist(trafo(c_me), c_you))
           return false;
 
@@ -2010,17 +2003,17 @@ namespace netgen
       return true;
   }
 
-  void Identify(const TopoDS_Shape & me, const TopoDS_Shape & you, string name, Identifications::ID_TYPE type, std::optional<gp_Trsf> opt_trafo) 
+  void Identify(const TopoDS_Shape & me, const TopoDS_Shape & you, string name, Identifications::ID_TYPE type, std::optional<std::variant<gp_Trsf, gp_GTrsf>> opt_trafo) 
   {
-    gp_Trsf trafo;
+    Transformation<3> trafo;
     if(opt_trafo)
     {
-        trafo = *opt_trafo;
+        trafo = occ2ng(*opt_trafo);
     }
     else
     {
-        auto v = GetCenter(you) - GetCenter(me);
-        trafo.SetTranslation(gp_Vec(v[0], v[1], v[2]));
+        auto v = occ2ng(Center(you)) - occ2ng(Center(me));
+        trafo = Transformation<3>(v);
     }
 
     ListOfShapes list_me, list_you;
@@ -2029,10 +2022,8 @@ namespace netgen
     Identify(list_me, list_you, name, type, trafo);
   }
 
-  void Identify(const ListOfShapes & me, const ListOfShapes & you, string name, Identifications::ID_TYPE type, gp_Trsf occ_trafo) 
+  void Identify(const ListOfShapes & me, const ListOfShapes & you, string name, Identifications::ID_TYPE type, Transformation<3> trafo) 
   {
-    Transformation<3> trafo = occ2ng(occ_trafo);
-
     ListOfShapes id_me;
     ListOfShapes id_you;
 
diff --git a/libsrc/occ/occgeom.hpp b/libsrc/occ/occgeom.hpp
index d266c69d..45859026 100644
--- a/libsrc/occ/occgeom.hpp
+++ b/libsrc/occ/occgeom.hpp
@@ -351,8 +351,8 @@ namespace netgen
     //bool FastProject (int surfi, Point<3> & ap, double& u, double& v) const;
   };
 
-  void Identify(const ListOfShapes & me, const ListOfShapes & you, string name, Identifications::ID_TYPE type, gp_Trsf occ_trafo);
-  void Identify(const TopoDS_Shape & me, const TopoDS_Shape & you, string name, Identifications::ID_TYPE type, std::optional<gp_Trsf> opt_trafo);
+  void Identify(const ListOfShapes & me, const ListOfShapes & you, string name, Identifications::ID_TYPE type, Transformation<3> trafo);
+  void Identify(const TopoDS_Shape & me, const TopoDS_Shape & you, string name, Identifications::ID_TYPE type, std::optional<std::variant<gp_Trsf, gp_GTrsf>> opt_trafo);
    
 
   void PrintContents (OCCGeometry * geom);
diff --git a/libsrc/occ/python_occ_basic.cpp b/libsrc/occ/python_occ_basic.cpp
index cdf338fe..276e783e 100644
--- a/libsrc/occ/python_occ_basic.cpp
+++ b/libsrc/occ/python_occ_basic.cpp
@@ -9,11 +9,13 @@
 #include "occgeom.hpp"
 
 #include <BRepBuilderAPI_Transform.hxx>
+#include <BRepBuilderAPI_GTransform.hxx>
 #include <gp_Ax1.hxx>
 #include <gp_Ax2.hxx>
 #include <gp_Ax2d.hxx>
 #include <gp_Ax3.hxx>
 #include <gp_Trsf.hxx>
+#include <gp_GTrsf.hxx>
 
 using namespace netgen;
 
@@ -264,7 +266,27 @@ DLL_HEADER void ExportNgOCCBasic(py::module &m)
         }), py::arg("p")=gp_Pnt2d(0,0), py::arg("d")=gp_Dir2d(1,0))
     ;
 
-
+  py::class_<gp_GTrsf>(m, "gp_GTrsf")
+    .def(py::init([](const std::vector<double>& mat,
+                     const std::vector<double>& vec)
+         {
+           if(mat.size() != 9)
+             throw Exception("Need 9 matrix values for construction of gp_GTrsf");
+           if(vec.size() != 3)
+             throw Exception("Need 3 vector values for construction of gp_GTrsf");
+           gp_GTrsf trafo;
+           trafo.SetVectorialPart({ mat[0], mat[1], mat[2],
+               mat[3], mat[4], mat[5],
+               mat[6], mat[7], mat[8] });
+           trafo.SetTranslationPart( { vec[0], vec[1], vec[2] });
+           return trafo;
+         }), py::arg("mat"), py::arg("vec") = std::vector<double>{ 0., 0., 0. })
+    .def("__call__", [] (gp_GTrsf & trafo, const TopoDS_Shape & shape) {
+        BRepBuilderAPI_GTransform builder(shape, trafo, true);
+        PropagateProperties(builder, shape, occ2ng(trafo));
+        return builder.Shape();
+      })
+    ;
   
   py::class_<gp_Trsf>(m, "gp_Trsf")
     .def(py::init<>())    
diff --git a/libsrc/occ/python_occ_shapes.cpp b/libsrc/occ/python_occ_shapes.cpp
index 99f58086..5304eefa 100644
--- a/libsrc/occ/python_occ_shapes.cpp
+++ b/libsrc/occ/python_occ_shapes.cpp
@@ -1098,7 +1098,7 @@ DLL_HEADER void ExportNgOCCShapes(py::module &m)
          })
 
 
-    .def("Identify", py::overload_cast<const TopoDS_Shape &, const TopoDS_Shape &, string, Identifications::ID_TYPE, std::optional<gp_Trsf>>(&Identify),
+    .def("Identify", py::overload_cast<const TopoDS_Shape &, const TopoDS_Shape &, string, Identifications::ID_TYPE, std::optional<std::variant<gp_Trsf, gp_GTrsf>>>(&Identify),
             py::arg("other"), py::arg("name"),
             py::arg("type")=Identifications::PERIODIC, py::arg("trafo")=nullopt,
             "Identify shapes for periodic meshing")
@@ -1689,10 +1689,16 @@ DLL_HEADER void ExportNgOCCShapes(py::module &m)
                       OCCGeometry::global_shape_properties[shape.TShape()].quad_dominated = quad_dominated;
                   })
     
-    .def("Identify", py::overload_cast<const ListOfShapes&, const ListOfShapes&, string, Identifications::ID_TYPE, gp_Trsf>(&Identify),
-            py::arg("other"), py::arg("name"),
-            py::arg("type")=Identifications::PERIODIC, py::arg("trafo"),
-            "Identify shapes for periodic meshing")
+    .def("Identify", [](const ListOfShapes& me,
+                        const ListOfShapes& other,
+                        string name,
+                        Identifications::ID_TYPE type,
+                        std::variant<gp_Trsf, gp_GTrsf> trafo)
+    {
+      Identify(me, other, name, type, occ2ng(trafo));
+    }, py::arg("other"), py::arg("name"),
+         py::arg("type")=Identifications::PERIODIC, py::arg("trafo"),
+         "Identify shapes for periodic meshing")
 
     ;