When move the viewpoint around the centre of your Local node, looking always towards the centre of the basis, and more precisely towards an object placed in that centre.
This way to move around the Viewpoint is usually known as the "world in the hand" Metaphor.
A Metaphor is a way to explain to users of a program how to use its interface. You say "Do it as if you where doing something else that you already know". The most well-known ones are of course the "Desktop" 2D Metaphor invented by Xerox, developed and popularised by Apple. It says that to access the information available in a computer, you should have the same behaviour as in front of a real desktop. You could open a "folder" from which you get a "file" that you could "open", "write" into and "close"...
As 3D world is more difficult to work with than 2D one, there are lots of metaphors around to represent the way to deal with that sort of world.
A ray between the "avatar" of your hand and the object. A Laser pointer which need a 3D mouse.