In Place mode allows you to display biped motion as if it were occurring on a treadmill. Regardless of the distance the biped covers under control of the current motion file, the biped stays within the active viewport when you've turned on In Place Mode.
In Place playback prevents lateral (XY) movement of the biped center of mass during animation playback; vertical motion along the Z-axis is preserved. Biped limbs, footsteps, and center of mass keys can be adjusted in this mode. When the center of mass is moved on the XY axes in this mode, the footsteps move.
Use this feature to view biped playback without requiring a follow camera. In this viewing mode, visible footsteps appear to slide under the biped.
For export to games, this feature is valuable, as many game engines intelligently move the character's center of mass laterally according to game play. In Place mode makes it easy to view, tune, and export animation in a manner that is complementary to game engine playback.
The In Place Mode button is the default button on a three-button flyout. There are two further options:
Using In Place Mode to Adjust Keyframes
In Place Mode is a good way to adjust keys on a biped that already has animation applied to it. Rather than scrolling the view at different frames to keep a running biped visible, turn on In Place Mode. Now when you scrub the time slider, or use the Next Key and Previous Key buttons, the biped remains visible. A key that needs adjustment can be quickly spotted and corrected.
To use In Place mode to adjust keyframes:
(If the rollout is already expanded, the bar shows a minus sign at the left, instead of a plus.)