Unlike the Pan tool, adjusts the height of the current viewpoint along Z axis of the model.
To adjust the vertical elevation of the current view, you drag up or down. As you drag, the current elevation and the allowed range of motion is displayed on a graphical element called the Vertical Distance indicator.
The Vertical Distance indicator has two marks that show the highest (Top) and lowest (Bottom) elevation possible for the view.The Vertical Distance indicator is displayed.
