Human perception of material properties in the real world

Humans are very good at recognizing objects as well as the materials that they are made of. We can easily tell cheese from butter, silk from linen and snow from ice just by looking. Understanding material perception is important for many real-world applications. For instance, a robot cooking in the kitchen will benefit from the knowledge of material perception when deciding if food is cooked or raw. In this talk, I will present studies that are motivated by two important applications of material perception: online shopping and computer graphics (CG) rendering. First, I will discuss the image cues that allow humans to infer tactile and mechanical information about deformable materials. I will present an experiment in which subjects were asked to match their tactile and visual perception of fabrics. I will show that image cues such as 3D folds and color are important for predicting subjects' tactile perception. Not only do these findings have immediate practical implications (e.g., improving online shopping interfaces for fabrics), but they also have theoretical implications: image-based visual cues affect tactile perception. Second, I will present a project on the visual perception of translucent materials (e.g., wax, milk, and jade) using computer-rendered stimuli. Humans are very sensitive to subtle differences in translucency (e.g., baby skin vs. adult skin), however, it is difficult to render translucent materials realistically. I will show how we measured the perceptual dimensions of physical scattering parameter space and used those measurements to produce more realistic renderings of materials like marble and jade. Taken together, my findings highlight the importance of material perception in the real world, and demonstrate how human perception can contribute to applications in computer vision and graphics.