Avatar facial expression representation in multidimensional space
Examples of the disclosed systems and methods may provide for improved and more realistic rendering of virtual characters and a more realistic interaction between a user and virtual characters. For example, the systems and methods describe techniques for mathematically generating a map used for animating facial expressions in a multidimensional animation blendspace. As another example, the systems and methods describe a transition system for dynamically transitioning facial expressions across a face of the virtual character. As another example, realistic physical movements can be added to a virtual character's facial expressions to provide interactivity with other virtual characters.
1. A system for animating a virtual character, the system comprising:
non-transitory storage medium storing control systems for facial expressions of a virtual character in a multidimensional vector space, wherein the control systems comprise a plurality of face sliders representing vector component values for the facial expressions of the virtual characters in the multidimensional vector space, the face sliders implemented with tunable springs, wherein an angular difference between vectors in the multidimensional vector space corresponds to a difference in emotion type between facial expressions associated with the vectors; and wherein a difference in magnitude between the vectors corresponds to a difference in intensity of emotion between the facial expressions associated with the vectors;
a display for rendering the virtual character; and
a hardware processor programmed to:
detect a trigger for changing the virtual character's facial expression in a transition from a first facial expression represented by a first vector to a second facial expression represented by a second vector;
determine one or more of the plurality of face sliders to be updated in response to the trigger for the transition between the first vector for the first facial expression to the second vector for the second facial expression;
determine a target value of a face slider of the one or more face sliders;
update a value of the face slider to the target value;
apply a tunable spring to the face slider in response to a determination that the target value is reached; and
cause the display to render the virtual character to show a change from the first facial expression to the second facial expression with the tunable spring.
2. The system of claim 1 , wherein the face slider controls one or more vertices of a mesh of the virtual character.
3. The system of claim 1 , wherein the tunable spring causes a cyclic motion to be performed on a region controlled by the face slider.
4. The system of claim 1 , wherein the tunable spring represents an underdamped oscillation asymptotic to the target value.
5. The system of claim 1 , wherein the control systems further comprise a sweeping mechanism for changing the facial expression, and the sweeping mechanism causes the tunable spring to the face slider to occur at a different time than another tunable spring to another face slider.
6. The system of claim 1 , wherein the control systems further include, for the transition, a sweep direction representing a direction of change among portions of the face for the transition between the first vector to the second vector.
7. The system of claim 6 , wherein the sweep direction is randomized.
8. The system of claim 6 , wherein the sweep direction is independent from the trigger.
9. A method for animating a virtual character, the method comprising:
detecting a trigger for changing a virtual character's facial expression in a transition from a first facial expression represented by a first vector to a second facial expression represented by a second vector;
determining one or more face sliders of a control system of the virtual character to be updated in response to the trigger, the one or more face sliders representing vector component values for the facial expressions of the virtual characters in the multidimensional vector space, the face sliders implemented with tunable springs, wherein an angular difference between vectors in the multidimensional vector space corresponds to a difference in emotion type between facial expressions associated with the vectors; and wherein a difference in magnitude between the vectors corresponds to a difference in intensity of emotion between the facial expressions associated with the vectors;
determining a target value of a face slider of the one or more face sliders in response to the trigger for the transition between the first vector for the first facial expression to the second vector for the second facial expression,
wherein the face slider comprises a physicality implemented to simulate real world physical movements;
updating a value of the face slider to the target value;
activating a physicality for the face slider in response to a determination that a threshold condition is reached; and
causing a display to render the virtual character to show a change from the first facial expression to the second facial expression with the physicality.
10. The method of claim 9 , wherein the physicality comprises a tunable spring which causes cyclic motion to be performed on a region controlled by the face slider.
11. The method of claim 9 , wherein the face slider controls one or more vertices of a mesh of the virtual character.
12. The method of claim 9 , wherein the threshold condition comprises a threshold value below the target value.
13. The method of claim 9 , wherein the control systems further comprise a sweeping mechanism for changing the facial expression, and the sweeping mechanism causes the physicality to the face slider to occur at a different time than physicality to another face slider.
14. The method of claim 9 , wherein the transition includes a sweep direction representing a direction of change among portions of the face for the transition between the first vector to the second vector.
15. The method of claim 14 , wherein the sweep direction is randomized.
16. The method of claim 14 , wherein the sweep direction is independent from the trigger.