Working in 3D, in every view we always have at least two coordinate systems to work with — the DGN file coordinate system and the view coordinate system. Only in a Top view, do the two coordinate systems align exactly. When we rotate a view, in reality we are repositioning our view "camera" to let us see the model from a different direction. Thus, when we rotate a view, the DGN file's axes rotate with it. Each view's axes, on the other hand, are relative to the view (or, if you like, the screen) and the following always applies for view axes:
- The x-axis is horizontal and positive from left to right.
- The y-axis is vertical and positive from bottom to top.
- The z-axis is perpendicular to the view (screen), and positive toward you.
Thus, you can place elements relative to the DGN file coordinates, or relative to the view coordinates. When you use AccuDraw, this is easier to understand as its compass gives you a visual indication of the drawing plane in which you are working.