SIZE CONSTANCY IN STRUCTURE-FROM-MOTION

The relative motions of points in a structure-from-motion display invo lving parallel projection provide depth information in an object-cente red framework: differences in velocity do not reflect differences in d istance from an eyepoint. In contrast, size constancy is generally reg arded to be a perspective effect, based on the relationship between pr ojected size and distance from an eyepoint. Five subjects judged the r elative sizes of objects in structure-from-motion scenes. Although the scenes were displayed without perspective, judged size was related to the simulated separation in depth of the objects. These results sugge st that relative depths recovered from object-centered information are incorporated into a viewer-centered framework.