Civil 3D提供的基于.net的API和基于COM的API，现在推荐大家使用.net API,但有时也需要使用COM API。 这个例子演示如何使用COM API来导入DEM数据生成Civil 3D曲面。 Civil 3D开发中使用COM API需要添加的引用比较啰嗦，建议使用向导创建项目简化操作，向导能帮助你添加大部分引用，如果还缺什么，自己再添加就简单多了。注意使用COM API，需要勾选AutoCAD 和Civil 3D的interOp相关引用。

下面是使用COM API导入DEM数据的代码：

// (C) Copyright 2013 by Autodesk 

//

using System;

using Autodesk.AutoCAD.Runtime;

using Autodesk.AutoCAD.ApplicationServices;

using Autodesk.AutoCAD.DatabaseServices;

using Autodesk.AutoCAD.Geometry;

using Autodesk.AutoCAD.EditorInput;

using System.Windows.Forms;

using Autodesk.AECC.Interop.UiLand;

using Autodesk.AutoCAD.Interop;

using Autodesk.Civil.ApplicationServices;





// This line is not mandatory, but improves loading performances

[assembly: CommandClass(typeof(LoadDEM_demo.MyCommands))]



namespace LoadDEM_demo

{





    public class MyCommands

    {

 





        // COM objects:

        private Autodesk.AutoCAD.Interop.IAcadApplication m_oAcadApp = null;

        private Autodesk.AECC.Interop.UiLand.IAeccApplication m_oAeccApp = null;

        private Autodesk.AECC.Interop.UiLand.IAeccDocument m_oAeccDoc = null;

        private Autodesk.AECC.Interop.Land.IAeccDatabase m_oAeccDb = null;

        string m_sAcadProdID = "AutoCAD.Application";

        string m_sAeccAppProgId = "AeccXUiLand.AeccApplication.10.0"; //Civil 3D 2013

        //string m_sAeccAppProgId = "AeccXUiLand.AeccApplication.9.0"; //Civil 3D 2012

        private string m_sMessage = "";





        [CommandMethod("LoadDemSurfaceop")]

        public void LoadDemSurface()

        {



            try

            {

                OpenFileDialog ofd = new OpenFileDialog();

                ofd.Filter = "USGS DEM( *.DEM) |*.dem|GEOTIFF(*.tif)|*.tif|ESRI ASCII 栅格（*.asc）|*.asc|ESRI ASCII 栅格（*.txt）|*.txt|ESRI 二进制栅格（*.adf）|*.adf";

                ofd.FilterIndex = 0;

                if (ofd.ShowDialog() == DialogResult.OK)

                {

                    //use COM

                    m_oAcadApp = (IAcadApplication)System.Runtime.InteropServices.Marshal.GetActiveObject(m_sAcadProdID);

                    if (m_oAcadApp != null)

                    {

                        m_oAeccApp = (IAeccApplication)m_oAcadApp.GetInterfaceObject(m_sAeccAppProgId);

                        m_oAeccDoc = (IAeccDocument)m_oAeccApp.ActiveDocument;



                        m_oAeccDoc.Surfaces.ImportDEM(ofd.FileName);

                    }



                    m_oAeccDoc.Regen(Autodesk.AutoCAD.Interop.Common.AcRegenType.acActiveViewport);





                }

                else

                {



                }

            }

            catch (System.Exception e)

            {

                MessageBox.Show(e.Message);

            }

            finally

            {



            }

        }

       

   





    }



}