Nature Neuroscience
1, 275 - 277 (1998)
doi:10.1038/1089
Three-dimensional object recognition is viewpoint dependentMichael J. Tarr1, Pepper Williams2, William G. Hayward3
& Isabel Gauthier41
Brown University, Department of Cognitive and Linguistic
Sciences, Box 1978, Providence, Rhode
Island 02912, USA
2
University of Massachusetts, Department of Psychology
, 100 Morrissey Boulevard, Boston,
Massachusetts 02125-3393, USA
3
University of Wollongong, Department of Psychology
, Northfields Avenue, Wollongong, NSW
2552, Australia
4
Yale University, Department of Psychology,
PO Box 208205, New Haven, Connecticut 06520-8205
, USA
Correspondence should be addressed to Michael J. Tarr Michael_Tarr@brown.eduThe human visual system is faced with the computationally difficult problem
of achieving object constancy: identifying three-dimensional (3D) objects
via two-dimensional (2D) retinal images that may be altered when the same
object is seen from different viewpoints1. A widely accepted
class of theories holds that we first reconstruct a description of the object's
3D structure from the retinal image, then match this representation to a remembered
structural description. If the same structural description is reconstructed
from every possible view of an object, object constancy will be obtained.
For example, in Biederman's2 oft-cited recognition-by-components
(RBC) theory, structural descriptions are composed of sets of simple 3D volumes
called geons (Fig. 1), along with the spatial
relations in which the geons are placed. Thus a mug is represented in RBC
as a noodle attached to the side of a cylinder, and a suitcase as a noodle
attached to the top of a brick. The attraction of geons is that, unlike more
complex objects, they possess a small set of defining properties that appear
in their 2D projections when viewed from almost any position (e.g., all three
views of the brick in Fig. 1 include a straight main
axis, parallel edges, and a straight cross section). According to the RBC
theory, a complex object can therefore be recognized from its constituent
geons, which can themselves be recognized from any viewpoint.
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