A Constraint-Based Approach to Visual Speech for a Mexican-Spanish Talking Head

Table 1

Boundary constraints.

Constraints	Action
𝑆(𝑡start) = 𝜀start	Ensures trajectory starts at 𝜀start
𝑆(𝑡end) = 𝜀end	Ensures trajectory ends at 𝜀end
𝑆 (𝑡start)^′ = 𝑆 (𝑡end)^′ = 0	Ensures the velocity is equal to zero at the beginning and end of the trajectory
𝑆 (𝑡start)^′′ = 𝑆(𝑡end)^′′=0	Ensures the acceleration is equal to zero at the beginning and end of the trajectory