【ord c#】create from elements

老师好，我想问下我现在利用图中的按钮创建地形，代码如下：

  public void CreateTerrain(List<DPoint3d> points)
        {
            // List<DPoint3d> points = new List<DPoint3d>();
            DTM dtm = new DTM();
            DTMFeatureType featureType = Helpers.ConvertFromSurfaceFeatureType(SurfaceFeatureType.Boundary);
            dtm.AddLinearFeature(points, featureType);
            dtm.SetTriangulationParameters(0.001, 0.001, DTMEdgeOption.RemoveSliver, 0.0);
            dtm.Triangulate();
            DTMElement dtmElement = new DTMElement(Session.Instance.GetActiveDgnModel(), (Bentley.DgnPlatformNET.Elements.Element)null, dtm);
            //DTM名称
            dtmElement.Name = "Test";
            dtmElement.AddToModel();
        }