Navigation

Gravitational effects during navigation: Fixes the X, Y, or Z axis during navigation.
Follow ground at altitude (in mm): First, select the Gravitational effects during navigation check box to be able to select this option.
Animation during viewpoint modification: Set this option if you want viewpoint changes in certain contexts to be animated.
Disable the rotation sphere display: Hides the rotation sphere usually displayed when rotating an object.

Fly/Walk

Show navigation icon: Lets you display the Walk or Fly target when navigating.

Mouse-free navigation: Lets you fly or walk through objects without using the mouse, only the keyboard.

Collision detection enabled: Select this check box to make collision detection options available. Then, activate a collision mode by selecting the appropriate option below.
Point/scene collision: When flying and walking, detects if you collide with an object, so that you bounce off the object instead of going through it.
User-defined collision detection distance (in mm): Similar to Point/scene collision, except that you can decide a distance at which it detects objects for collision, and slides according to navigation direction during walk or fly.
Start speed: Lets you fly at the default speed or at the speed you define.

Sets the time interval (from 0 to 100 milliseconds) during which mouse movements are not taken into account for prehighlight purposes.

Sets the angle value applied when rotating objects using the keyboard.

Ensures use of maximum available space when viewing models using the Fit All In command.