Virtual Trackball

The virtual trackball works as if there is an invisible ball in the center of the scene. When you click and drag on the screen, it is as if you put your finger on the sphere and rotated it in approximately the same manner. If you click outside the sphere, then you get rotation about the Z-axis only.

Generally, the view will be easiest to control by clicking in the center of the scene and moving outwards (mostly XY-rotation).