Abstract
Every image executed according to the rules of linear perspective, such as a photograph, has a center of the perspective construction. Only when viewed from this location does the imaged scene exactly project into its picture. However, in everyday viewing of images the choice of an appropriate vantage point is not recognized as a problem, and very few observers even know of the existence of such geometrically privileged observation locations. It has been suggested that the visual system tolerates large deviations from the projectively correct vantage point, or that mechanisms exist that actively compensate for incorrect vantage points. However, there are studies that indicate that different choices of vantage points do induce different impressions of geometrical layouts of virtual 3D spaces conveyed by the same image. Here I present a series of experiments that demonstrate such effects. The image used as the stimulus was a photograph of a street receding obliquely into distance, and the task of the subjects was to judge its orientation with respect to the environment. In the first experiment the image was presented as a large billboard at a city intersection, and the subjects were located at various directions and distances around it. In the second experiment it was presented as a poster hanged in a hall, and the subjects were located at two distances and four directions from it. In the third experiment the same image was embedded in a computer-generated virtual scene and depicted from several vantage points. The results have indicated strong and systematic effects of vantage point positions on the perceived orientation of the street. They can be generally accounted for by the assumption that the visual system treats the image as the projection of a scene from the perspective center located at the current vantage point of the observer.
Meeting abstract presented at VSS 2017