Digital Transmission of Subjective Material Appearance

The digital recreation of real-world materials has a substantial role in applications such as product design, on-line shopping or video games. Since decisions in design or shopping are often driven by qualities like “softness” or “beautifulness” of a material (rather than its photo-accurate visual depiction), a digital material should not only closely capture the texture and reflectance of the physical sample, but also its subjective feel. Computer graphics research constantly struggles to trade physical accuracy against computational efficiency. However, the connection between measurable properties of a material and its perceived quality is subtle and hard to quantify. Here, we analyze the capability of a state-of-the-art model for digital material appearance (the spatially-varying BRDF) to transport certain subjective qualities through the visual channel. In a psychophysical study, we presented users with measured material SVBRDFs in the form of rendered still images and animations, as well as photographs and physical samples of the original materials. The main insight from this experiment is that photographs reproduce better those qualities associated with the sense of touch, particularly for textile materials. We hypothesized that the abstraction of volumetric materials as opaque and flat textures destroys important visual cues especially in border regions, where fluff and protruding fibers are most prominent. We therefore performed a follow-up experiment where the border regions have been removed from the photographs. The fact that this step greatly reduced the capability of photos to transport important qualities suggests strong directions of future research in applied perception and computer graphics.