Extraction of relief from visual motion

Werkhoven, Peter; Veen, H.A.H.C. van

doi:10.3758/bf03213270

Cited by 17 publications

(10 citation statements)

References 19 publications

(29 reference statements)

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“…Moreover, experiments have been presented assessing internal consistency of the metric judgments in shape from shading (Koenderik, van Doom, & Kappers, 1992) and full cues environmerits (F. N. Norman, Todd, Perotti, & Tittle, 1996). This issue has been addressed only recently for structure-from-motion (SFM) displays by Werkhoven and van Veen (1995), who found that observers are inaccurate in making depth relief judgments. …”

Section: The Modelmentioning

confidence: 99%

Recovery of 3-D structure from motion is neither euclidean nor affine.

Domini¹,

Braunstein²

1998

Journal of Experimental Psychology: Human Perception and Perfor

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The relationship between simulated and judged depth separations for pairs of probe dots on planar surface patches was examined in a series of 6 experiments. The simulated slant of the patches was varied without varying the simulated depth separation of the probe dots by varying the depth gradient orthogonal to the direction determined by the probe dots on the image plane. Judged depth separation varied with mean slant for constant simulated depth separations. When observers judged depth separations along a closed path, the integral of the signed depths did not sum to zero, as would be required in Euclidean geometry. These results are inconsistent with the view that the mapping between simulated and perceived 3-D structure is alfme and indicate that, in general, the perceived structure cannot be represented in either a Euclidean space or an affine space. Moreover, these results are consistent with a first-order temporal analysis of the optic flow. A pattern of moving two-dimensional (2-D) features on a flat screen can give rise to a compelling impression of three-dimensionality. This phenomenon has been called the kinetic depth effect (Wallach & O'Connell, 1953) or structure from motion (Uliman, 1979). Numerous attempts have been made to understand the underlying perceptual process and to answer the question of how the three-dimensional (3-D) properties of the perceived object are related to characteristics of the moving pattern. Much of the research on this topic has been influenced by the computational approach to vision (Marr, 1982) and has sought algorithms that could recover the real structure of the distal objects from moving patterns. Indeed, the main issue has been to find the minimal conditions and constraints that are sufficient for an ideal observer to recover the 3-D Euclidean structure of an object from 2-D moving images and to investigate the psychological validity of the theoretical findings (see Braunstein, Hoffman, Shapiro, Andersen, & Bennett, 1987, for a discussion). Recently, the view that the structure derived by the perceptual system has the same Euclidean properties as the Fulvio Domini, Cognitive Technology Laboratory (a collaboration between the

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Section: The Modelmentioning

confidence: 99%

Recovery of 3-D structure from motion is neither euclidean nor affine.

Domini¹,

Braunstein²

1998

Journal of Experimental Psychology: Human Perception and Perfor

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“…Perceived shape in this condition is usually nonveridical. Previous studies indicate that SFM is recovered from the first-order velocity field, which implies that shape is recoverable only up to a scaling factor in depth (Norman & Todd, 1993;Todd, 1998;Todd & Norman, 1991;Werkhoven & van Veen, 1995). Hence, accuracy is low for judgments requiring veridical perception of Euclidean metric structure, such as judgments of lengths or angles (Braunstein, Liter, & Tittle, 1993;Cornilleau-Peres & Droulez, 1989;Eagle & Blake, 1995;Hogervorst, Kappers, & Koenderink, 1993;Liter, Braunstein, & Hoffman, 1993;Norman & Lappin, 1992;Todd & Bressan, 1990).…”

Section: Introductionmentioning

confidence: 99%

Shape constancy and depth-order violations in structure from motion: A look at non-frontoparallel axes of rotation

Fernandez

Farell

2007

Journal of Vision

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Humans can recover the structure of a 3D object from motion cues alone. Recovery of structure from motion (SFM) from the projected 2D motion field of a rotating object has been studied almost exclusively in one particular condition, that in which the axis of rotation lies in the frontoparallel plane. Here, we assess the ability of humans to recover SFM in the general case, where the axis of rotation may be slanted out of the frontoparallel plane. Using elliptical cylinders whose cross section was constant along the axis of rotation, we find that, across a range of parameters, subjects accurately matched the simulated shape of the cylinder regardless of how much the axis of rotation is inclined away from the frontoparallel plane. Yet, we also find that subjects do not perceive the inclination of the axis of rotation veridically. This combination of results violates a relationship between perceived angle of inclination and perceived shape that must hold if SFM is to be recovered from the instantaneous velocity field. The contradiction can be resolved if the angular speed of rotation is not consistently estimated from the instantaneous velocity field. This, in turn, predicts that variation in object size along the axis of rotation can cause depth-order violations along the line of sight. This prediction was verified using rotating circular cones as stimuli. Thus, as the axis of rotation changes its inclination, shape constancy is maintained through a trade-off. Humans perceive the structure of the object relative to a changing axis of rotation as unchanging by introducing an inconsistency between the perceived speed of rotation and the first-order optic flow. The observed depth-order violations are the cost of the trade-off.

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“…In contrast, we have shown that biases in recovered three-dimensional dihedral angle can be explained from an analysis in which all geometric relevant information is used without relying on prior preferences for particular dihedral angles. We have also developed a simple model of the noise on early motion measurements to explore the consequences for threedimensional shape recovery which, with some exceptions (Nakayama 1985;Eagle & Blake 1995;Werkhoven & van Veen 1995;Eagle & Hogervorst 1997), have largely been ignored. Thus, the biases emerge naturally when a realistic model of SFM estimation is considered.…”

Section: Discussionmentioning

confidence: 99%

Biases in three–dimensional structure–from–motion arise from noise in the early visual system

Hogervorst

Eagle

1998

Proc. R. Soc. Lond. B

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The projected pattern of retinal-image motion supplies the human visual system with valuable information about properties of the three-dimensional environment. How well three-dimensional properties can be recovered depends both on the accuracy with which the early motion system estimates retinal motion, and on the way later processes interpret this retinal motion. Here we combine both early and late stages of the computational process to account for the hitherto puzzling phenomenon of systematic biases in three-dimensional shape perception. We present data showing how the perceived depth of a hinged plane (`an open book') can be systematically biased by the extent over which it rotates. We then present a Bayesian model that combines early measurement noise with geometric reconstruction of the three-dimensional scene. Although this model has no in-built bias towards particular threedimensional shapes, it accounts for the data well. Our analysis suggests that the biases stem largely from the geometric constraints imposed on what three-dimensional scenes are compatible with the (noisy) early motion measurements. Given these ¢ndings, we suggest that the visual system may act as an optimal estimator of three-dimensional structure-from-motion.

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Extraction of relief from visual motion

Cited by 17 publications

References 19 publications

Recovery of 3-D structure from motion is neither euclidean nor affine.

Recovery of 3-D structure from motion is neither euclidean nor affine.

Shape constancy and depth-order violations in structure from motion: A look at non-frontoparallel axes of rotation

Biases in three–dimensional structure–from–motion arise from noise in the early visual system

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