A model for the rapid interpretation of line drawings in early vision

According to the prevailing view, the elements of early visual processing are characterized by simple geometric properties such as length, orientation, and curvature. We demonstrate in this chapter that this view must be revised—the elements of early vision need not be geometrically simple. Instead, they can be characterized in terms of environmental relevance, computational architecture, and processing speed. We begin by summarizing the conventional view of early vision and point to several problems it encounters. We then re-examine the role played by the elements of early vision, arguing that it is advantageous for them to describe environmentally relevant properties, even if these quantities are not always valid. As an illustration, we develop a computational model for the rapid recovery of one important scene property from line drawings—the three-dimensional orientation of objects. Data from recent visual search experiments in humans are presented in support of the model.