Film-makers and computer game designers are using increasingly sophisticated animation techniques in their products. One area that still causes them problems is the realistic representation of human skin. The way in which skin reflects and absorbs light changes with emotion, physical stress and even after drinking alcohol. Subconsciously we expect these changes and we miss them when they are not present in animations.
Dr Tim Weyrich at UCL Computer Science and colleagues measured how light is scattered and absorbed by the skin. They recorded changes as volunteers made different facial expressions, ran up and down nine flights of stairs or drank a pint of beer. They then produced a model of how skin colour changes and incorporated this into traditional face animation software. Using this software, an animator may create facial expressions by deforming a face geometry, as they would usually do, while the new appearance model automatically changes skin colour to match the facial expressions.