Real-Time Rendering of Skin Changes Caused by Emotions

For simulating communicative behavior, realistic appearance and plausible behavior is important. Postures and mimics also reflect emotional behavior. There exist various models of emotion, like the psycho-evolutionary theory developed by Plutchik [1], or Ekman’s FACS. But most models are only suited for muscular expressions. A more unattended field however, also in graphics, is the change in color. Also, other physiological symptoms like crying are left unconsidered. In contrast to the central nervous system, which is responsible for the conscious control of motor functions, the autonomic nervous system (ANS) controls unconscious inner functions that can result in physical reactions like blushing and pallor. Blushing [2,3] can occur when a sensation is very intense. Usually the cheeks are affected: there is a correlation between blushing and increase of temperature [3,4], especially in the forward facing upper regions. An average blushing takes Δt = 35s with the strongest intensity after 15s. Face and ears also blush. Pallor is caused by a reduction of blood flow [2] e.g. due to fear. Regions that blush can also get pale. Other vegetative functions that are controlled by the ANS are weeping (sometimes accompanied by blushing) and sweat.