Recognizing Material Properties from Images

Humans implicitly rely on the properties of materials to guide our interactions. Grasping smooth materials, for example, requires more care than rough ones. We may even visually infer non-visual properties (e.g., softness is a physical material property). We refer to visually-recognizable material properties as visual material attributes. Recognizing these attributes in images can provide valuable information for scene understanding and material recognition. Unlike typical object and scene attributes, however, visual material attributes are local (i.e., "fuzziness" does not have a shape). Given full supervision, we may accurately recognize such attributes from purely local information (small image patches). Obtaining consistent full supervision at scale, however, is challenging. To solve this problem, we probe the human visual perception of materials. By asking simple yes/no questions comparing pairs of image patches, we obtain the weak supervision required to build a set of classifiers for attributes that, while unnamed, function similarly to the attributes with which we describe materials. Furthermore, we integrate this method in the end-to-end learning of a CNN that simultaneously recognizes materials and their visual attributes. Experiments show that visual material attributes serve as both a useful representation for known material categories and as a basis for transfer learning.