KineBody

6DOF Body Motion

This section provides instructions for using KineBody Pro’s 6th DOF (degree of freedom) features.

Dial Angle

In KineBody Basic, the 5 degrees of freedom for full body motion include 3 translations (horizontal, vertical, and distance) and two rotations (spin and tilt). KineBody Pro supplements these with a 3rd rotation, called the 'dial' angle, which controls rotation of the body in the plane of the screen (or equivalently, about an axis perpendicular to the screen). As with the other DOF, the dial angle can be adjusted several ways, including a slider (at the bottom of the screen) and a joystick method (i.e. by dragging across the viewing area); the 90 degree step rotations (described below) can also change the dial angle.

Note that the dial angle influences the other two rotations: the green (tilt) axis changes direction to follow the dial angle, and the blue (spin) axis moves in a plane, which remains perpendicular to the green axis. This behavior has implications for how you adjust the spin and tilt angles, i.e. it's not quite as simple as for KineBody Basic. (Nevertheless, you'll find that it's still very intuitive, especially with the new rotation axes display, described here).

1. To rotate the body in the plane of the screen, adjust the dial angle, using either of these two methods:
   1. Via the dial angle slider: drag horizontally, starting anywhere in the dial slider box.
   2. Via the joystick technique: Hold the [Alt] key down, while dragging the cursor along a circular path, around the center point of the viewing area, to change the dial angle. Note that the sense (CW or CCW) of rotation is defined by the trajectory of the cursor relative to the viewing area centerpoint, e.g., CW rotation can occur by dragging downward on the right side of the viewing area, or upward on the left side.


2. To rotate the body around the green axis, adjust the tilt angle, using either of these two methods:
   1. Via the tilt angle slider.
   2. Via the joystick technique: Drag the cursor perpendicular to the green line. (The body may spin as well, if you don't drag exactly perpendicular).
      
      (This is much like the 5DOF joystick technique, where you drag vertically for tilt; now, you may have to drag at an angle, if the body axis isn't vertical).


3. To rotate the body around the blue axis, adjust the spin angle, using either of these two methods:
   1. Via the spin angle slider.
   2. Via the joystick technique: Drag the cursor perpendicular to the blue line. (The body may tilt as well, if you don't drag exactly perpendicular).
      (This is much like the 5DOF joystick technique, where you drag horizontally for spin; now, you may have to drag at an angle, if the body axis isn't vertical).
   
   
4. To adjust the tilt and spin angles together, use the joystick technique, combining the methods of (3b) and (4b) above.
   

   'Casual' Mode for Angles

   KineBody Pro uses a special convention for reporting angles, which we call 'casual' mode. The standard convention for defining the orientation of a body in space, in terms of angles, is to use 'principal values': a range of ±180° is used for two of the angles, whereas the third uses a ±90° range. This convention makes it possible to report the angles with no ambiguity: there's a one-to-one correspondence between angles and orientations. A drawback of this method is that the angles can change abruptly, even as you change the orientation smoothly.

   KineBody's casual mode avoids this jumping, by defining all three rotation angles over a ±180° range. With this method, there's some redundancy in the angle values: each spatial orientation can be represented by two different sets of angles. This drawback is insignificant for most KineBody usage scenarios. (An optional 'strict' mode can be added to KineBody, to enforce the typical principal values, if there is sufficient demand).

Step Rotations

In addition to the sliders and joystick technique, KineBody Pro offers an additional way to manipulate the skeleton: the full body can be rotated in 90° steps, using intuitive pushbuttons (located in the lower-right corner), around any of 3 screen-fixed axes (horizontal, vertical, or normal to the screen). [The axes for these step rotations are not shown - in part, because they don't change direction, and also to alleviate unnecessary clutter and confusion with the regular red, green, and blue axes]. The step rotation buttons are available only in KineBody Pro, because such rotations are inherently 6DOF – they allow you to reach positions that aren't possible using just 5 DOF.

Along with the step rotation buttons, an additional button is provided to return the body to its 'home' position, by setting all body rotations to zero. This button affects the body position only (defined as that of the thorax); it doesn't alter any of the joint angles.