Learning to See Stereokinetic Effects

Perception ◽  
1987 ◽  
Vol 16 (2) ◽  
pp. 187-192 ◽  
Author(s):  
Paola Bressan ◽  
Giorgio Vallortigara
Keyword(s):  
Rigid Body ◽  
Structure From Motion ◽  
Incubation Time ◽  
Stimulus Pattern ◽  
Circular Ring ◽  
Frontoparallel Plane ◽  
Stereokinetic Effect ◽  
Flat Pattern

The Saturn illusion is a stereokinetic effect that occurs when a flat pattern composed of a full ellipse with two symmetrical semirings is rotated slowly in the frontoparallel plane. Subjects report seeing an egg-shaped object inserted into a circular ring, and the two objects move solidly into 3-D space as a single rigid body. Inexperienced observers show a conspicuous delay before reaching this percept. Two experiments are reported in which it is shown that this incubation time progressively decreases with repeated exposures to the stimulus pattern. A certain amount of time (14 s on average) is, however, required to obtain the effect, even after six successive exposures. It is argued that this time, which is independent of the speed of rotation and is not further reducible, is a fixed entity and is needed to compute the most rigid 3-D solution from deformations in the 2-D image. The results are discussed in relation to current theories of perception of structure from motion.

Multiple 3-D Interpretations in a Classic Stereokinetic Effect

Perception ◽  
1986 ◽  
Vol 15 (4) ◽  
pp. 405-408 ◽  
Author(s):  
Paola Bressan ◽  
Giorgio Vallortigara
Keyword(s):  
Prolonged Exposure ◽  
Frontal Plane ◽  
Circular Disc ◽  
Frontoparallel Plane ◽  
Circular Trajectory ◽  
Axis Ratio ◽  
Stereokinetic Effect ◽  
Flat Pattern

It is known that a flat ellipse rotating in the frontoparallel plane sooner or later appears as a rigid circular disc tilting in 3-D space. An experiment is reported in which prolonged exposure to the same flat pattern produces a second previously unnoticed 3-D percept: an elongated egg slanted in 3-D space, which points towards the observer and the end parts of which describe a circular trajectory in the frontal plane. It is shown that the achievement of this alternative percept is not affected by the particular shape of the ellipse, although the time needed to reach it increases with an ellipse with a 2:3 axis ratio.

Stereokinesis with Moving Visual Phantoms

Perception ◽  
1987 ◽  
Vol 16 (1) ◽  
pp. 73-78 ◽  
Author(s):  
Paola Bressan ◽  
Giorgio Vallortigara
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Major Axis ◽  
Circular Ring ◽  
Frontoparallel Plane ◽  
Flat Pattern ◽  
Three Dimensional Space

When a flat pattern composed of a solid ellipse with two symmetrical semirings (corresponding to the visible parts of a contour ellipse whose major axis is perpendicular to that of the solid ellipse) is slowly rotated in the frontoparallel plane, a compelling three-dimensional impression occurs. Subjects report seeing an egg-shaped object that is inserted into a circular ring: the two objects move solidly into three-dimensional space and a moving visual phantom is generated so that the ring appears completed by an illusory curved bar in the region closest to the observer during rotation. A number of variations of this illusion are presented. It is shown that stereokinetic phantoms (i) maintain the shape of the inducing elements; (ii) appear only after the stereokinetic transformation has taken place; and (iii) depend on the organization of the three-dimensional percept as a whole. Relations between stereokinetic phantoms and other completion phenomena are presented and discussed.

scholarly journals A Heavy Elastic Circular Ring Partially Supported by a Rigid Body

1969 ◽  
Vol 12 (52) ◽  
pp. 709-714
Author(s):  
Katsuo SUGIURA
Keyword(s):  
Rigid Body ◽  
Circular Ring

Perception of Depth in Rotating Objects: 3. Asymmetry and Velocity as the Determinants of the Stereokinetic Effect

1968 ◽  
Vol 26 (3) ◽  
pp. 671-681 ◽  
Author(s):  
Betty A. Wieland ◽  
Roy B. Mefferd
Keyword(s):  
Internal Structure ◽  
Horizontal Axis ◽  
Apparent Depth ◽  
Frontoparallel Plane ◽  
Stereokinetic Effect ◽  
Rotating Objects

When a flat stimulus is rotated in the frontoparallel plane about a horizontal axis that is an extension of O's line of regard, the apparent depth of the stimulus is enhanced. The enhancement was entirely a function of peripheral asymmetry. The apparent depth in the static figure, internal structure, or taper in the periphery did not augment the rotation-enhanced depth. The magnitude of the enhancement was constant for any series of stimuli, such as a series of overlapping circles with increasing overlap. The apparent depth also increased as a function of the speed of rotation.

Rapid mapping accuracy assessment using low-cost UAV and open-source Structure from Motion

2020 ◽  
Vol 52 ◽  
pp. 55-61
Author(s):  
Ettore Potente ◽  
Cosimo Cagnazzo ◽  
Alessandro Deodati ◽  
Giuseppe Mastronuzzi
Keyword(s):  
Open Source ◽  
Structure From Motion ◽  
Accuracy Assessment ◽  
Low Cost ◽  
Mapping Accuracy ◽  
Rapid Mapping ◽  
Source Structure

IN VITRO UPTAKE OF RADIOACTIVE 131I LABELLED L-TRIIODOTHYRONINE BY HUMAN ERYTHROCYTES AS AN INDEX OF THYROID FUNCTION

1960 ◽  
Vol XXXIV (II) ◽  
pp. 305-311 ◽  
Author(s):  
M. G. Woldring ◽  
A. Bakker ◽  
H. Doorenbos
Keyword(s):  
Thyroid Function ◽  
Incubation Time ◽  
Clinical Results ◽  
Human Erythrocytes ◽  
Red Cell ◽  
Clinical Value ◽  
Blood Samples ◽  
In Vitro Uptake

ABSTRACT The red cell triiodothyronine uptake technique as used in our hospital is described. Incubation time is of almost no importance. The temperature during incubation should be 37° C. Further improvement of the technique is obtained when all blood samples are brought up to 40 % haematocrit prior to incubation. Clinical results are discussed. It is yet too early to give a definite assessment of its clinical value, but it is definitely superior to the measurement of the BMR.

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