请问如何使用ArcEngine实现另存为sxd格式的文件？

SceneControl中保存sxd就是通过IPersistStream接口实现的，参考下面代码：
如果想在ArcScene中打开的话，可以使用上述代码在ArcScene上做个Add-in工具，打开文件，将其在ArcScene中显示。
//save sxd 
IMemoryBlobStream mbStream = new MemoryBlobStreamClass();
IObjectStream objectStream = new ObjectStreamClass(); 
objectStream.Stream = mbStream; 
IPersistStream persistStream = (ESRI.ArcGIS.esriSystem.IPersistStream)axSceneControl1.Scene;
persistStream.Save(objectStream, 1); 

saveFileDialog1.Title = "保存Scene文档"; 
saveFileDialog1.Filter = "保存Scene文档(*.sxd)|*.sxd"; 
saveFileDialog1.ShowDialog(); 
string filename = saveFileDialog1.FileName; 

mbStream.SaveToFile(filename); 
MessageBox.Show("OK"); 

//open engine-saved sxd 
openFileDialog1.Title = "打开Scene文档"; 
openFileDialog1.Filter = "Scene文档(*.sxd)|*.sxd"; 
openFileDialog1.ShowDialog(); 
string filename = openFileDialog1.FileName; 
if (axSceneControl1.CheckSxFile(filename)) 
axSceneControl1.LoadSxFile(filename); 
else 
{ 
IScene pScene = axSceneControl1.Scene; 
IMemoryBlobStream mbStream = new MemoryBlobStreamClass();
IObjectStream objectStream = new ObjectStreamClass(); 
mbStream.LoadFromFile(filename); 
IPersistStream pPersistStream = (ESRI.ArcGIS.esriSystem.IPersistStream)pScene; 
objectStream.Stream = mbStream; 
pPersistStream.Load(objectStream); 
}