Movie S3.

Lambertian surfaces can appear compellingly translucent in diffuse illumination. Both surfaces have the same bumpy 3D shape and were rendered as fully opaque Lambertian surfaces. The only difference between the two surfaces is the way they are being illuminated. The surface in the first half of the movie is embedded in natural illumination, which as a predominant direction of illumination from overhead. The surface in the second half of the movie is embedded in a Ganzfeld (fully diffuse illumination), and generates a compelling illusory percept of translucency (Fig. 4 and Figs. S1 and S2).