We present a novel setup in which real objects made of different materials can be mixed optically. For the materials we chose mutually very different materials, which we assume to represent canonical modes. The appearance of 3D objects consisting of any material can be described as linear superposition of 3D objects of different canonical materials, as in "painterly mixes". In this paper we studied mixtures of matte, glossy and velvety objects, representing diffuse, forward and asperity scattering modes. Observers rated optical mixtures on four scales: matte-glossy, hard-soft, cold-warm, light-heavy. The ratings were done for the three combinations of glossy, matte, and velvety green birds. For each combination we tested 7 weightings. Matte-glossy ratings varied most over the stimuli and showed highest (most glossy) scores for the rather glossy bird and lowest (most matte) for the rather velvety bird. Hard-soft and cold-warm were rated highest (most soft and warm) for rather velvety and lowest (most hard and cold) for rather glossy birds. Light-heavy was rated only somewhat higher (heavier) for rather glossy birds. The ratings varied systematically with the weights of the contributions, corresponding to gradually changing mixtures of material modes. We discuss a range of possibilities for our novel setup.
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