diff --git a/Objects/Converters/ConverterAutocadCivil/ConverterAutocadCivilShared/ConverterAutocadCivil.Civil.cs b/Objects/Converters/ConverterAutocadCivil/ConverterAutocadCivilShared/ConverterAutocadCivil.Civil.cs
index b81e00b677..116e3c0a77 100644
--- a/Objects/Converters/ConverterAutocadCivil/ConverterAutocadCivilShared/ConverterAutocadCivil.Civil.cs
+++ b/Objects/Converters/ConverterAutocadCivil/ConverterAutocadCivilShared/ConverterAutocadCivil.Civil.cs
@@ -736,44 +736,40 @@ private Featureline FeaturelineToSpeckle(CivilDB.CorridorFeatureLine featureline
   public Mesh SurfaceToSpeckle(TinSurface surface)
   {
     // output vars
-    List<Point3d> vertices = new();
-    var faces = new List<int>();
+    List<double> vertices = new();
+    List<int> faces = new ();
+    Dictionary<Point3d, int> indices = new();
+    
+    int indexCounter = 0;
     foreach (var triangle in surface.GetTriangles(false))
     {
-      var triangleVertices = new List<Point3d> { triangle.Vertex1.Location, triangle.Vertex2.Location, triangle.Vertex3.Location };
-
-#if CIVIL2023 || CIVIL2024 // skip any triangles that are hidden in the surface!
-      if (!triangle.IsVisible)
-      {
-        triangle.Dispose();
-        continue;
-      }
-#endif
-
-      // store vertices
-      var faceIndices = new List<int>();
-      foreach (var vertex in triangleVertices)
+      try
       {
-        if (!vertices.Contains(vertex))
+        Point3d[] triangleVertices = { triangle.Vertex1.Location, triangle.Vertex2.Location, triangle.Vertex3.Location };
+        foreach (Point3d p in triangleVertices)
         {
-          faceIndices.Add(vertices.Count);
-          vertices.Add(vertex);
-        }
-        else
-        {
-          faceIndices.Add(vertices.IndexOf(vertex));
+          if (!indices.ContainsKey(p))
+          {
+            var scaledP = ToExternalCoordinates(p);
+            vertices.Add(scaledP.X);
+            vertices.Add(scaledP.Y);
+            vertices.Add(scaledP.Z);
+            indices.Add(p, indexCounter);
+            indexCounter++;
+          }
         }
+        faces.Add(3);
+        faces.Add(indices[triangleVertices[0]]);
+        faces.Add(indices[triangleVertices[1]]);
+        faces.Add(indices[triangleVertices[2]]);
+      }
+      finally
+      {
+        triangle.Dispose();
       }
-
-      // get face
-      faces.AddRange(new List<int> { 3, faceIndices[0], faceIndices[1], faceIndices[2] });
-
-      triangle.Dispose();
     }
-
-    var speckleVertices = vertices.SelectMany(o => PointToSpeckle(o).ToList()).ToList();
-
-    var mesh = new Mesh(speckleVertices, faces)
+    
+    var mesh = new Mesh(vertices, faces)
     {
       units = ModelUnits,
       bbox = BoxToSpeckle(surface.GeometricExtents)
@@ -962,7 +958,7 @@ public ApplicationObject TinSurfaceToNative(Mesh mesh, Base props)
         {
           continue;
         }
-
+        
         var a1 = surface.FindVertexAtXY(edgeStart.X, edgeStart.Y);
         var a2 = surface.FindVertexAtXY(vertexToAdd.X, vertexToAdd.Y);
         surface.AddLine(a1, a2);
diff --git a/Objects/Converters/ConverterAutocadCivil/ConverterAutocadCivilShared/ConverterAutocadCivil.Geometry.cs b/Objects/Converters/ConverterAutocadCivil/ConverterAutocadCivilShared/ConverterAutocadCivil.Geometry.cs
index 134621830f..385a38ec5e 100644
--- a/Objects/Converters/ConverterAutocadCivil/ConverterAutocadCivilShared/ConverterAutocadCivil.Geometry.cs
+++ b/Objects/Converters/ConverterAutocadCivil/ConverterAutocadCivilShared/ConverterAutocadCivil.Geometry.cs
@@ -57,12 +57,9 @@ public Point PointToSpeckle(Point2d point, string units = null)
 
   public Point3d PointToNative(Point point)
   {
-    var _point = new Point3d(
-      ScaleToNative(point.x, point.units),
-      ScaleToNative(point.y, point.units),
-      ScaleToNative(point.z, point.units)
-    );
-    var intPt = ToInternalCoordinates(_point);
+    var scaleFactor = Units.GetConversionFactor(point.units, ModelUnits);
+    var scaledPoint = new Point3d(point.x * scaleFactor, point.y * scaleFactor, point.z * scaleFactor);
+    var intPt = ToInternalCoordinates(scaledPoint);
     return intPt;
   }