The following is a summary of “Qualitative perception of 3D shape from patterns of luminance curvature,” published in the May 2023 issue of Ophthalmology by Todd, et al.
The study introduced a new approach for perceiving three-dimensional (3D) shapes from shading, specifically focusing on identifying surface concavities based on the curvature of the luminance field. Two experiments were conducted to assess human observers’ ability to detect concavities on smoothly curved shaded surfaces using various illumination patterns and material properties. Participants were tasked with identifying any apparent concavities along designated cross-sections of the depicted objects and marking them with an adjustable dot.
To analyze the data, the researchers calculated the surface curvature and the luminance curvature along each image cross-section. The findings demonstrated that most responses corresponded to concave regions of the luminance profiles, although they often exhibited a phase shift relative to the curvature of the depicted surfaces. Notably, the performance pattern remained consistent even when the illumination and surface material properties varied.
Furthermore, the analysis predicted that observers would make false alarm responses in regions where a luminance concavity did not align with a surface concavity, and the empirical results validated this prediction. Overall, the study presented evidence for the effectiveness of using luminance curvature as a cue for perceiving concavities in shaded 3D objects, with the observed pattern of performance holding up across different illumination and material conditions.