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 the judgements made when viewing a physical sample of the same material. We demonstrate this approach using 16 diverse physical material samples that were 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 for individual physical material specimens. In the second experiment we asked subjects to assess the same attributes for the same materials rendered as BTFs under point-light and environment illuminations. By analysis of the 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 the physical material appearance.