ViewVector is an option for Graphics3D and related functions which specifies the position and direction of a simulated camera used to view three-dimensional objects.
With the default setting ViewVector->Automatic, the position and direction of the simulated camera is determined by the settings for ViewPoint and ViewCenter.
ViewVector specifies that the camera should be at the position with coordinates , aimed in the direction specified by ViewCenter.
ViewVector specifies that the camera should be aimed in the direction of the point .
Scaled coordinates can be used.
How much the simulated camera sees is determined by settings for ViewAngle and ViewRange.