Computer graphics processing and selective visual display system – Computer graphics processing – Animation
Reexamination Certificate
1998-07-30
2002-12-31
Nguyen, Phu K. (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Animation
Reexamination Certificate
active
06501477
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a motion data generation apparatus, a motion data generation method, and a motion data generating program storage medium, which are used in a field of computer graphics animation, and, more particularly, to an apparatus and a method for automatically generating closed-loop periodic motion data from time-series motion data resulting from connecting single or plural open time-series motion data given for moving a multi-joint rigid body object.
BACKGROUND OF THE INVENTION
Definitions will be described before discussing a main subject. In the computer graphics animation, as shown in FIG.
6
(
a
), a skeletal structure equivalent to the bones of a multi-joint rigid body object is defined to move a human and a creature modeled by the multi-joint rigid body object realistically, and the motion of a human is decided by the motion of the skeletal structure.
In FIG.
6
(
a
), ES denotes an end site corresponding to that of a human; JT, a joint corresponding to that of a human; LK, a link corresponding to a bone of a human; ST, a segment corresponding to a higher hierarchical part constituting a human, such as a neck, arm, or leg.
Motion data of the skeletal structure is time-series data. A concept of motion data of an object, such as a human and a creature modeled by a multi-joint rigid body object, in the computer graphics animation will be described with reference to FIG.
6
(
b
). In the figure, a model of multi-joint rigid body object is a human. As described above, the motion data is generally time-series data. The motion data comprises three posture angles Aa, Av, and Ah used for controlling the posture of the whole object, a slide vector indicating the amount of parallel translation used for controlling the movement of each joint, and a joint angle Aj indicating the amount of rotation.
To indicate the position of a whole object O, a point P is predetermined and fixed inside each object. To indicate the posture of the whole object O, a movement direction vector Va, an upward direction vector Vv, and a lateral direction vector Vh are defined, and called posture vectors.
With a coordinate system introduced by the fixed point P and the posture vectors Va, Vv, and Vh, the position of each joint of the object can be inherently determined. As opposed to this, in the computer graphics, each object has its own coordinate system, called an object coordinate system, for defining its shape. Hence, the origin of the object coordinate system is the point P indicating the position of the whole object O. Unit vectors defining the object coordinate system are the posture vectors.
The posture angles Aa, Av, and Ah are the amounts of rotation abut the three axes of a world coordinate system (x, y, z). To calculate the posture vectors Va, Vv, and Vh at a certain time, the posture vectors in the initial state are rotationally converted about X, Y, and Z axes by the respective amounts of rotation. The posture of the whole object is thus controlled at each time. The movement of a joint is controlled by parallel translation by a slide vector, and rotation about each axis, in a local coordinate system defined for each joint. Although the foregoing discussion is based on a multi-joint rigid body object, this invention is not restricted to a rigid body or a multi-joint object. Other kinds of body or a single joint, or the combination of those can be employed in this invention.
The motion data comprises three posture angles used for controlling the posture of the whole object, a slide vector indicating the amount of parallel translation used for controlling the movement of each joint, and a joint angle indicating the amount of rotation.
To indicate the position of a whole object, a point is predetermined and fixed inside each object. To indicate the posture of the whole object, a movement direction vector, an upward direction vector, and a lateral direction vector are defined, and called posture vectors. This situation is shown in FIG.
6
(
b
). With a coordinate system introduced by the fixed point and the posture vectors, the position of each joint of the object can be inherently determined.
As opposed to this, in the computer graphics, each object has its own coordinate system, called an object coordinate system, for defining its shape. Hence, the origin of the object coordinate system is the point indicating the position of the whole object. Unit vectors defining the object coordinate system are the posture vectors. The posture angles are the amounts of rotation about the three axes of a world coordinate system. To calculate the posture vectors at a certain time, the posture vectors in the initial state are rotationally converted about the three axes by the respective amounts of rotation. The posture of the whole object is thus controlled at each time. The movement of a joint is controlled by parallel translation by a slide vector, and rotation about each axis, in a local coordinate system defined for each joint.
As shown in FIG.
7
(
b
), the time-series motion data of the position of an object at an initial time does not match that at a last time. The local movements of the object are different at all between at the initial time and at the last time. This motion is called an open non-periodic motion. That is, when the same open non-periodic motion is continuously repeated, the state at the last time transfers abruptly to the state at the initial time, while the object suddenly jumps from the position at the last time to that at the initial time. Therefore, the motion cannot be repeated.
An open periodic motion is a motion, as shown in FIG.
7
(
b
), in which the position of the object at the initial time does not match that at the last time, but the states of an object at the last time and at the initial time are almost the same, so the object transfers from the state at the last time to that at the initial time, naturally and smoothly. When the same open periodic motion is continually repeated, the transition of the state of the object is always natural and smooth, but as to the position of the object, the object suddenly jumps from the position at the last time to that at the initial time. Therefore, the motion cannot be repeated, either.
As opposed to those, a closed-loop periodic motion is a motion, as shown in FIG.
7
(
c
), in which as to both the state and the position of an object, there is no abrupt transition, or no sudden jump to anywhere not expected. Therefore, the motion can be repeated.
Time-series motion data as a result of connection of plural time-series motion data becomes an open non-periodic motion unless the data is subjected to a special processing described below in this invention.
By the way, recently, in the field of computer graphics animation, always required is realistic motions of a creature, such as a human, modeled by a multi-joint rigid body object.
Three-dimensional time-series data representing such motions are generated by an animator using a method including key-framing interpolation, or a motion capture technique which is a 3-D motion measuring technique capturing real movements.
It takes a long time to process motions generated by such methods, and the motions are generated basically as open time-series data which is a unit having a minimum meaning as a movement, taking into account that the generated movement is reused. Hence, those small pieces of motion must be connected to get a series of motion over a long time. However, the motion data resulting from connection of open time-series motion data becomes inevitably open time-series motion data.
There are several conventional methods of connecting motion data. The most primitive one of those methods is a method such that an expert called the foregoing animator estimates a motion connecting between monitors, and producing the motion data of the connecting motion by handiwork. However, the method has poor productivity, and because the work of estimating a motion in three-dimensional space depends on the experience of an animator, the connecting motion produc
Mochizuki Yoshiyuki
Naka Toshiya
Burr & Brown
Matsushita Electric - Industrial Co., Ltd.
Nguyen Phu K.
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