diff --git a/Tree.cpp b/Tree.cpp
index 81efe12..5efb8ee 100644
--- a/Tree.cpp
+++ b/Tree.cpp
@@ -1393,7 +1393,7 @@ Tree::GetPolygons( POLYLINEMATRIX& vvPolygons, POLYLINEMATRIX& vvPolygons3d, vec
    }
 
    // se richiesto aggiorno gli edge 3d e i loop della superficie
-   if ( bUpdateEdges) {
+   if ( bUpdateEdges  ||  vvCCEdges3D.empty()) {
       GetEdges3D( vvCCEdges3D, vPolygonsCorrected) ;
       GetSplitLoops( vCCLoops) ;
    }