Computer animation method and system for synthesizing human-like gestures and actions

• US 6,115,053 A
• Filed: 08/02/1994
• Issued: 09/05/2000
• Est. Priority Date: 08/02/1994
• Status: Expired due to Fees

• Current Assignee: New York University
• Original Assignee: New York University
• Inventors: Perlin, Kenneth
• Primary Examiner(s): Powell, Mark R.
• Assistant Examiner(s): ROSSI, JEFFREY A
• Application Number:
  US08/284,799
• Time in Patent Office: 2,226 Days
• Field of Search: 395/152 MS, 395/152, 395/173-175, 395/949-960, 345/122, 345/473, 345/475
• US Class Current: 345/475
• CPC Class Codes: G06T 13/40 of characters, e.g. humans, animals or virtual beings

Abstract

A computer animation method for creating computer generated animated characters which realistically perform human-like actions. Actions of an animated character are produced as a combination of motions of a plurality of joints. A number of gesture actions are displayed and defined as a series of frames generated by specifying rotational ranges and speeds of rotation on a number of rotational axes of each joint for each gesture action. The actions of each animated character appear as a weighted average of gesture actions. Gesture actions may also be combined and displayed simultaneously. By gradually varying the weight of active gesture actions, transitions between gestures are smooth and realistic.

Claims

1. A computer animation method for creating animated characters which include body members coupled at joints and which perform movement gesture actions, the computer animation method comprising the steps of:

selecting a first gesture action and a second different gesture actions from a library of stochastically defined movement gesture actions, each of the first and second gesture actions being defined by values over time for a set of parameters which govern a movement at the joints of the animated characters;

rendering the animated characters as a function of the first gesture action;

further rendering the animated characters by transitioning between the first gesture action and the second gesture action by diminishing during a predetermined time interval a weight of the values of the parameters of the first gesture action and simultaneously increasing during the predetermined time interval a weight of the values of the parameters of the second gesture action to provide a smooth transition between the first and second gesture actions;

wherein the library of stochastically defined movement gesture actions includes at least one composite gesture action controlling a plurality of movements at a plurality of joints of the animated character.

2. A method for creating animated characters as in claim 1 wherein:

the set of parameters for each joint define rotations about three mutually orthogonal axes at each joint; and

the parameters include maximum and minimum limits of rotation and a functional description of joint movement variation over time between the maximum and minimum limits of rotation.

3. A method for creating animated characters as in claim 1 further comprising the step of assigning attractant and repellant vectors to define relationships between each animated character and one or more obstacles.

4. A method for creating animated characters as in claim 1 wherein the weights of preselected gesture actions of two or more animated characters are determined as a function of at least one of a distance and an orientation between the characters.

5. A method for creating animated characters as in claim 1 wherein at least one movement constraint is imposed on the gesture actions of the animated characters.

7. A method for creating animated characters as in claim 1 wherein the character has nineteen of the joints.

8. A method for creating animated characters as in claim 1 wherein the set of parameters of a gesture action includes a speed of rotation which is a function of noise.

6. A computer animation method for creating animated characters by creating a library of gesture actions to be selected in sequence by a user, comprising the steps of:

defining each of the animated characters as having a plurality of at least ten universal joints, each of the universal joints being defined by rotational movement about three mutually orthogonal axes;

via a software program, defining, for each action a set of parameters for each axis of rotation at each of the universal joints, the parameters including a maximum angle of rotation excursion, a minimum angle of rotation excursion and a speed of rotation; and

rendering the animated characters as a function of the selection by the user, wherein the library of gesture actions includes at least one composite gesture action controlling a plurality of movements at a plurality of joints.

9. A method for creating animated characters that convey emotion through their gestures, comprising the steps of:

(a) generating scene transformations and images to be rendered as a function of scalar input parameters;

(b) determining, for each respective gesture at each frame of animation, a weight of a set of parameters representative of the respective gesture, wherein the respective gesture is invoked if a weight of the respective gesture is a nonzero value;

(c) calculating values over time for the set of parameters of each of the gestures;

(d) performing a weighted sum of values for each of the set of parameter within each of the gestures for which the parameter is defined;

(e) analyzing the transformation matrices to produce scalar variables; and

(f) modifying the weight of the set of parameters representative of at least one gesture as a function of the scalar variables and determining the scalar input parameters for generating corresponding scene transformations and images.

10. A method for creating animated characters as in claim 9 wherein the set of parameters include limits on rotation and speed of rotation.

11. A method for creating animated characters as in claim 9 further comprising the step of assigning attractant and repellant vectors to define relationships between each animated character and one or more obstacles.

12. A method for creating animated characters as in claim 9 wherein the weights of preselected gesture actions of two or more animated characters are determined as a function of at least one of a distance and an orientation between the characters.

13. A method for creating animated characters as in claim 9 wherein at least one movement constraint is imposed on the gesture actions of the animated characters.

14. A computer animation system for creating animated characters that convey emotion through their gestures, comprising:

a library of stochastically defined movement gesture actions;

scene description modules programmed with information to simulate a natural motion of the gestures by the animated characters;

a goal determination module for computing, for each of the gestures, a weight of a set of parameters representative of a respective gesture of the gestures to determine whether the scene description modules should simulate the respective gesture; and

an analyzer receiving information from the scene description modules to convey to the goal determination module whether to increase, decrease or keep constant the weight of individual gestures

to enable a smooth transition from one gesture to the next and restricting a character movement.

15. A computer animation system as in claim 14 wherein said scene description modules generate scene transformations and images to be rendered as a function of scalar input parameters.

16. A computer animation system as in claim 14 wherein one scene description module generates scene transformations in dependence on the scene transformations generated by another scene description module.

17. A computer animation system as in claim 14 wherein said goal determination module determines the weight for each gesture at each frame of animation.

18. A computer animation system as in claim 14 wherein the character is a human and a gesture is invoked if its weight is non-zero.

19. A computer animation system as in claim 14 wherein each gesture creates values over time for a set of parameters.

20. A computer animation system for creating animated characters which appear to move in a succession of image frames, said computer animation system comprising:

a library of gesture actions programmed with information to simulate the natural motion of gestures as expressed by the movement of body parts thereof through joint angles;

each joint angle being expressed by the parameters of rotation about three axes and the parameters including limits of rotation excursion and speed of rotation; and

each frame having each character body part movement defined by the parameters at each axis of each joint,

wherein transitions between gestures are achieved by simultaneously decreasing a weight of one gesture and increasing a weight of a subsequent gesture.

21. A computer animation system as in claim 20 wherein the movement of animated characters conforms to conditions apparent in each scene, such that characters avoid obstacles, enter and exit openings, and move in compliance with physical laws.

22. A computer animation method for creating animated characters which include a plurality of body members coupled at a plurality of joints and which perform movement gesture actions, the computer animation method comprising the steps of:

selecting first and second different gesture actions from a library of stochastically defined movement gesture actions, the first gesture action being defined by values over time for a first set of parameters, the first set of parameters controlling a first movement at a first joint of the plurality of joints and a second movement at a second joint of the plurality of joints, the second gesture action being defined by values over time for a second set of parameters, the second set of parameters controlling a third movement of at least the first joint of the plurality of joints;

rendering the animated characters as a function of the first gesture action; and

during a predetermined time interval, further rendering the animated characters by diminishing a weight of the values of the first set of parameters of the first gesture action and simultaneously increasing a weight of the values of the second set of parameters of the second gesture action to provide a smooth transition between the first and second gesture actions, wherein the transition between the first and second gesture actions effect a first movement at the first joint without effecting a second movement at the second joint.