Parameterized Skin for Rendering Flushing Due to Exertion

Abstract

It is known that physical exercise increases bloodflow and flushing of the facial skin. When digital artists hand-paint the textures for animation of realistic effects such as flushing due to exertion, they observe real-life references and use their creativity. This process is empirical and time-consuming, with artists often using the same textures across all facial expressions. The problem is that there is a lack of guidelines on how skin color changes due to exertion, that is only surpassed when scans of facial appearance are used. However facial appearance scans are best suited when creating digital doubles and do not easily fit different characters. Here, we present a novel delta-parameterized method that guides artists in painting the textures for animation of flushing due to physical exertion. To design the proposed method we have analyzed skin color differences in L*a*b* color space, from 34 human subjects' portraits before and after physical exercise. We explain the experiment setup configuration, statistical analysis and the resulting delta color differences from which we derived our method parameters. We illustrate how our method suits any skin type and character style. The proposed method was reviewed by texture artists, who find it useful and that it may help render more realistic flushed exertion expressions, compared to state of the art, guesswork techniques.