Evaluating Physical and Rendered Material Appearance

Many representations and rendering techniques have been proposed for presenting material appearance in computer graphics. One outstanding problem is evaluating their accuracy. In this paper, we propose assessing accuracy by comparing human judgements of material attributes made when viewing a computer graphics rendering to those made when viewing a physical sample of the same material. We demonstrate this approach using 16 diverse physical material samples distributed to researchers at the MAM 2014 workshop. We performed two psychophysical experiments. In the first experiment, we examined how consistently subjects rate a set of twelve visual, tactile and subjective attributes of individual physical material specimens. In the second experiment, we asked subjects to assess the same attributes for identical materials rendered as BTFs under point-light and environment illuminations. By analyzing obtained data, we identified which material attributes and material types are judged consistently and to what extent the computer graphics representation conveyed the experience of viewing physical material appearance.