Index: Constructor/AppEnv.cs
===================================================================
--- Constructor/AppEnv.cs   (revision 6363)
+++ Constructor/AppEnv.cs   (working copy)
@@ -235,6 +235,18 @@
             set { vars["VECTORDATA5_OUTPUT_LNKD"].Value = value; }
         }

+        public string SurfaceL0Output
+        {
+            get { return vars["SURFACE_L0_OUTPUT"].StringValue; }
+            set { vars["SURFACE_L0_OUTPUT"].Value = value; }
+        }
+
+        public string SurfaceTempDir
+        {
+            get { return vars["SURFACE_TEMP_DIR"].StringValue; }
+            set { vars["SURFACE_TEMP_DIR"].Value = value; }
+        }
+
         public string RrrSceneOutput
         {
             get { return vars["RRR_SCENE_OUTPUT"].StringValue; }
Index: Constructor/Operations/ExportNavigationMesh.cs
===================================================================
--- Constructor/Operations/ExportNavigationMesh.cs  (revision 6363)
+++ Constructor/Operations/ExportNavigationMesh.cs  (working copy)
@@ -14,5 +14,20 @@
             : base("Navigation Mesh")
         {
         }
+
+        public override bool RunImp(Task task, AppEnv appEnv, bool withChildren)
+        {
+
+            Command command = new Command();
+            command.Type = Command.CommandType.EDTU4;
+            command.EdtuCommand = "build-navigation-mesh";
+            string surfaceL0filename = appEnv.SurfaceL0Output;
+            string navMeshfilename = appEnv.terrainConfig.TerrainCfgDir.AbsoluteByRelativeTcons() + "navigationMesh.navmesh";
+            command.Args = surfaceL0filename + " " + navMeshfilename;
+            command.ErrorsFile = appEnv.SurfaceTempDir + @"export-vector-data_errors.ofsh";
+            task.AddCommand(command);
+
+            return true;
+        }
     }
 }
Index: Constructor/Operations/TerrainConfig.cs
===================================================================
--- Constructor/Operations/TerrainConfig.cs (revision 6363)
+++ Constructor/Operations/TerrainConfig.cs (working copy)
@@ -305,6 +305,8 @@
             AddNewFileVariableIfNotFound(appEnv.vars, "RRR_OUTPUT");
             AddNewFileVariableIfNotFound(appEnv.vars, "VECTORDATA5_OUTPUT");
             AddNewFileVariableIfNotFound(appEnv.vars, "VECTORDATA5_OUTPUT_LNKD");
+            AddNewFileVariableIfNotFound(appEnv.vars, "SURFACE_L0_OUTPUT");
+            AddNewFileVariableIfNotFound(appEnv.vars, "SURFACE_TEMP_DIR");
             AddNewFileVariableIfNotFound(appEnv.vars, "RRR_SCENE_OUTPUT");
             AddNewFileVariableIfNotFound(appEnv.vars, "RRR_DETAILS_OUTPUT");
             AddNewFileVariableIfNotFound(appEnv.vars, "RRR_POWERLINES_OUTPUT");
@@ -403,6 +405,13 @@
             appEnv.ReferenceExternals = terrainCfgDir + @"SurfaceDetails\" + appEnv.TerrainName + ".external.ofsh";
             appEnv.TreePreviewArchive = terrainCfgDir + @"SurfaceDetails\Trees.preview.zip";

+            appEnv.SurfaceTempDir = tempDir;
+            if (VectorData5)
+                    appEnv.SurfaceTempDir += @"export-lsa4-with-vector-data-5\";
+            else
+                    appEnv.SurfaceTempDir += @"export-surface\";
+            appEnv.SurfaceL0Output = appEnv.SurfaceTempDir + "surface-L0.ofsh";
+
             System.IO.DirectoryInfo dirInfo = null;
             try
             {