Motion > Directional Modes > View Dependent
Defines the forward, back, left, and right motions based on the direction in which you are looking. The eye point to center point vector of the view cone defines this direction. Using the Forward/Backward, Left/Right mouse drag mode, forward moves you towards where you are looking. Back moves you away. Your elevation in the model changes using the View Dependent mode if the view cone is pointed up or down.
The View Dependent mode allows you to move directly toward where you are looking. The mouse drag modes, positioning modes, and Position Control toolbar all affect how this directional mode operates.
Click Motion > Directional Modes > View Dependent.
You can also click View Dependent on the View toolbar.