June 2006
Volume 6, Issue 6
Free
Vision Sciences Society Annual Meeting Abstract  |   June 2006
Velocity constancy in natural images
Author Affiliations
  • Andres Martin
    Departamento de Luminotectina, Luz y Vision. Universidad Nacional de Tucuman - Argentina
  • Jose F. Barraza
    Departamento de Luminotectina, Luz y Vision. Universidad Nacional de Tucuman and CONICET- Argentina
  • Luis A. Issolio
    Departamento de Luminotectina, Luz y Vision. Universidad Nacional de Tucuman and CONICET- Argentina
Journal of Vision June 2006, Vol.6, 1047. doi:10.1167/6.6.1047
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      Andres Martin, Jose F. Barraza, Luis A. Issolio; Velocity constancy in natural images. Journal of Vision 2006;6(6):1047. doi: 10.1167/6.6.1047.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose. Previous experiments showed that for realistic artificially generated stimuli depth cues such as parallax motion, disparity, size, perspective, and texture are necessary for velocity constancy. However, the relative size produced by relative distances would be sufficient to rescale retinal velocity. An ambiguity appears because a more distant object may be also interpreted as a smaller object located at the same distance unless one knows that those are the same object that did not change its size. Natural images provide this certainty. We investigated whether size is sufficient for velocity constancy in natural images. Methods. We performed a matching speed experiment to evaluate velocity constancy in natural images. Stimuli were generated by filming from different distances an athlete walking on a platform, which could move forward or backward at variable speeds. We processed the movies to remove all the cues except the size. Results. Results show high constancy factors for all subjects (ranging from 80 to 90%) with 83% mean. Although a little bias towards retinal velocity appears in this experiment, this is smaller than those obtained in the same condition using artificial stimuli. Conclusion. The relative size produced by the relative distance between objects provides more than 80% of the information used for velocity constancy in natural images. This suggests that the visual system would trust more on size information in natural than in artificial images perhaps, because in nature objects do not change its size.

Martin, A. Barraza, J. F. Issolio, L. A. (2006). Velocity constancy in natural images [Abstract]. Journal of Vision, 6(6):1047, 1047a, http://journalofvision.org/6/6/1047/, doi:10.1167/6.6.1047. [CrossRef] [PubMed]
Footnotes
 This work was supported by an ANPCyT-Argentina grant PICT 1315190 to AM and LAI and by ANPCyT grant PICT 0311687 and Fund Antorchas grant 14306/2 to JFB
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