diff --git a/Visibility_2/include/CGAL/Naive_visibility_2.h b/Visibility_2/include/CGAL/Naive_visibility_2.h
index 89ca4a32207..6204f43b379 100644
--- a/Visibility_2/include/CGAL/Naive_visibility_2.h
+++ b/Visibility_2/include/CGAL/Naive_visibility_2.h
@@ -256,6 +256,7 @@ public:
                 Intersection_type i_type = needle(active_edges, curr_vision_ray, collinear_vertices);
                 switch (i_type) {
                 case UNBOUNDED :
+                    //todo:this part is not finished.
                     //remove right and collinear;
                     remove_edges(active_edges, curr_vision_ray);
                     update_visibility(right_p, polygon, out_arr);
@@ -271,10 +272,10 @@ public:
                     remove_edges(active_edges, curr_vision_ray);
                     left_p = intersection_point(curr_vision_ray, active_edges[0]);
                     update_visibility(right_p, polygon, out_arr);
-
-                    update_visibility(collinear_vertices, polygon, out_arr);
+                    insert_needle(collinear_vertices, polygon, out_arr);
 //                    update_visibility(mid_p, polygon, out_arr);
-                    update_visibility(left_p, polygon, out_arr);
+//                    update_visibility(left_p, polygon, out_arr);
+                    polygon.push_back(left_p);
                     break;
                 case INNER :
                     //remove right and collinear;
@@ -285,8 +286,9 @@ public:
                     else {
                         left_p = intersection_point(curr_vision_ray, active_edges[0]);
                         update_visibility(right_p, polygon, out_arr);
-                        update_visibility(collinear_vertices, polygon, out_arr);
-                        update_visibility(left_p, polygon, out_arr);
+                        insert_needle(collinear_vertices, polygon, out_arr);
+//                        update_visibility(left_p, polygon, out_arr);
+                        polygon.push_back(left_p);
                     }
                     break;
                 }
@@ -294,7 +296,7 @@ public:
             vit = end_it;
         }
         if (!is_init_empty) {
-            CGAL::insert(out_arr, Segment_2(polygon.front(),polygon.back()));
+            CGAL::insert(out_arr, Segment_2(polygon.back(),polygon.front()));
         }
     }
 
@@ -496,9 +498,11 @@ private:
         }
     }
 
-    void update_visibility(const std::vector<Point_2>& points, std::vector<Point_2>& polygon, Arrangement_2 &arr){
-        for (int i = 0; i != points.size(); i++) {
-            update_visibility(points[i], polygon, arr);
+    void insert_needle(const std::vector<Point_2>& points, std::vector<Point_2>& polygon, Arrangement_2 &arr){
+        if (points.size() > 1) {
+            for (int i = 0; i != points.size()-1; i++) {
+                CGAL::insert(arr, Segment_2(points[i], points[i+1]));
+            }
         }
     }
 
diff --git a/Visibility_2/test/test_naive_visibility.cpp b/Visibility_2/test/test_naive_visibility.cpp
index aa0acbc8f28..a0c8186bc92 100644
--- a/Visibility_2/test/test_naive_visibility.cpp
+++ b/Visibility_2/test/test_naive_visibility.cpp
@@ -27,7 +27,7 @@ std::string number2string(T n) {
 }
 
 int main() {
-    int case_number = 5;
+    int case_number = 1;
     //test kernel Cartesian<Gmpq>
     {
         typedef CGAL::Gmpq                                              Number_type;
@@ -59,8 +59,8 @@ int main() {
                 if (!fit->is_unbounded()) break;
             } while (++fit != arr_in.faces_end());
             vb.visibility_region(Point_2(0, 0), fit, arr_vb);
-//            CGAL::Visibility_2::print_arrangement(arr_vb);
-//            CGAL::Visibility_2::print_arrangement(arr_ans);
+            CGAL::Visibility_2::print_arrangement(arr_vb);
+            CGAL::Visibility_2::print_arrangement(arr_ans);
             std::cout<<(true == (CGAL::test_are_equal<Arrangement_2>(arr_ans, arr_vb)))<<std::endl;
             std::cout<<CGAL::compare_arr_by_edges(arr_ans, arr_vb)<<std::endl;
         }