3D Alignment Location Different than 2D Alignment

 Applies To 
 Product(s):Power Rail Track
 Environment: N/A
 Area: Geometry
 Original Author:Jacquelyn Pettus, Bentley Technical Support Group










I notice that when I display a 3D alignment (Geometry > View Geometry > 3-D Alignment) it is in a different location than when I display a 2D alignment (Geometry > View Geometry > Active Horizontal).  Why is that?


MicroStation cannot precisely display a 3D arc.  When there is a change in elevation along the arc, the element is no longer a true arc. As soon as you add a vertical element, you are adding a 3rd dimension and there is no way to display a true arc. Therefore, when the element is displayed in MicroStation it must be planarized using stroking.