A new theory of structure-from-motion perception

Fernandez, Julian M.; Farell, Bart

doi:10.1167/9.11.23

Cited by 4 publications

(1 citation statement)

References 41 publications

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“…In this paradigm, the observer is assumed stationary and the three-dimensional structure of the environment is to be recovered. While initial theories attempted to recover object geometry from an inversion of the rules of (orthogonal or perspective) projection, more recently, theories have been proposed using local deformation of the retinal motion vector field (Domini & Caudek, 2003) or template matching (Fernandez & Farell, 2009). The distinction between ego-motion perception and structure from motion has been resolved in computer vision where algorithms have been developed solving both problems simultaneously (e.g., Luong & Faugeras, 1997).…”

Section: Introduction Ego-accelerationmentioning

confidence: 99%

Detection of linear ego-acceleration from optic flow

et al. 2012

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Human observers are able to estimate various ego-motion parameters from optic flow, including rotation, translational heading, time-to-collision (TTC), time-to-passage (TTP), etc. The perception of linear ego-acceleration or deceleration, i.e., changes of translational velocity, is less well understood. While time-to-passage experiments indicate that ego-acceleration is neglected, subjects are able to keep their (perceived) speed constant under changing conditions, indicating that some sense of ego-acceleration or velocity change must be present. In this paper, we analyze the relation of ego-acceleration estimates and geometrical parameters of the environment using simulated flights through cylindrical and conic (narrowing or widening) corridors. Theoretical analysis shows that a logarithmic ego-acceleration parameter, called the acceleration rate ρ, can be calculated from retinal acceleration measurements. This parameter is independent of the geometrical layout of the scene; if veridical ego-motion is known at some instant in time, acceleration rate allows updating of ego-motion without further depth-velocity calibration. Results indicate, however, that subjects systematically confuse ego-acceleration with corridor narrowing and ego-deceleration with corridor widening, while veridically judging ego-acceleration in straight corridors. We conclude that judgments of ego-acceleration are based on first-order retinal flow and do not make use of acceleration rate or retinal acceleration.

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Section: Introduction Ego-accelerationmentioning

confidence: 99%

Detection of linear ego-acceleration from optic flow

et al. 2012

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Discerning nonrigid 3D shapes from motion cues

Jain

Zaidi²

2011

Proc. Natl. Acad. Sci. U.S.A.

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Many organisms and objects deform nonrigidly when moving, requiring perceivers to separate shape changes from object motions. Surprisingly, the abilities of observers to correctly infer nonrigid volumetric shapes from motion cues have not been measured, and structure from motion models predominantly use variants of rigidity assumptions. We show that observers are equally sensitive at discriminating cross-sections of flexing and rigid cylinders based on motion cues, when the cylinders are rotated simultaneously around the vertical and depth axes. A computational model based on motion perspective (i.e., assuming perceived depth is inversely proportional to local velocity) predicted the psychometric curves better than shape from motion factorization models using shape or trajectory basis functions. Asymmetric percepts of symmetric cylinders, arising because of asymmetric velocity profiles, provided additional evidence for the dominant role of relative velocity in shape perception. Finally, we show that inexperienced observers are generally incapable of using motion cues to detect inflation/deflation of rigid and flexing cylinders, but this handicap can be overcome with practice for both nonrigid and rigid shapes. The empirical and computational results of this study argue against the use of rigidity assumptions in extracting 3D shape from motion and for the primacy of motion deformations computed from motion shears.optic-flow | structure-from-motion

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Advancement of motion psychophysics: Review 2001-2010

Nishida

2011

Journal of Vision

121

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This is a survey of psychophysical studies of motion perception carried out mainly in the last 10 years. It covers a wide range of topics, including the detection and interactions of local motion signals, motion integration across various dimensions for vector computation and global motion perception, second-order motion and feature tracking, motion aftereffects, motion-induced mislocalizations, timing of motion processing, cross-attribute interactions for object motion, motion-induced blindness, and biological motion. While traditional motion research has benefited from the notion of the independent "motion processing module," recent research efforts have been also directed to aspects of motion processing in which interactions with other visual attributes play critical roles. This review tries to highlight the richness and diversity of this large research field and to clarify what has been done and what questions have been left unanswered.

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A new theory of structure-from-motion perception

Cited by 4 publications

References 41 publications

Detection of linear ego-acceleration from optic flow

Detection of linear ego-acceleration from optic flow

Discerning nonrigid 3D shapes from motion cues

Advancement of motion psychophysics: Review 2001-2010

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