scholarly journals Blur Discrimination and its Relation to Blur-Mediated Depth Perception

Perception ◽  
10.1068/p3254 ◽  
2002 ◽  
Vol 31 (10) ◽  
pp. 1211-1219 ◽  
Author(s):  
George Mather ◽  
David R R Smith
Keyword(s):  
Depth Perception ◽  
Three Dimensional ◽  
The Other ◽  
Retinal Images ◽  
Apparent Depth ◽  
Depth Of Focus ◽  
Depth Cue ◽  
Series Of Experiments ◽  
Different Levels ◽  
Depth Ordering

Retinal images of three-dimensional scenes often contain regions that are spatially blurred by different amounts, owing to depth variation in the scene and depth-of-focus limitations in the eye. Variations in blur between regions in the retinal image therefore offer a cue to their relative physical depths. In the first experiment we investigated apparent depth ordering in images containing two regions of random texture separated by a vertical sinusoidal border. The texture was sharp on one side of the border, and blurred on the other side. In some presentations the border itself was also blurred. Results showed that blur variation alone is sufficient to determine the apparent depth ordering. A subsequent series of experiments measured blur-discrimination thresholds with stimuli similar to those used in the depth-ordering experiment. Weber fractions for blur discrimination ranged from 0.28 to 0.56. It is concluded that the utility of blur variation as a depth cue is constrained by the relatively mediocre ability of observers to discriminate different levels of blur. Blur is best viewed as a relatively coarse, qualitative depth cue.

Effect of Relative Positions of Segments on Strength of the Mueller-Lyer Illusion

1971 ◽  
Vol 33 (3_suppl) ◽  
pp. 1051-1058 ◽  
Author(s):  
Clive M. Davis ◽  
Marshall H. Segall
Keyword(s):  
Visual Field ◽  
Depth Perception ◽  
Interaction Effects ◽  
The Other ◽  
Relative Height ◽  
Lyer Illusion ◽  
Main Effect ◽  
Depth Cue

Segall, Campbell, and Herskovits (1966) postulated that the Mueller-Lyer illusion results from the misapplication of normally valid visual inference habits related to depth perception. To test the hypothesis that the depth cue of the relative height of the Mueller-Lyer segments in the visual field affects susceptibility, 100 Ss were presented two identical sets of 15 slides of Mueller-Lyer stimuli, one set with the >—–< above the <——> and the other set in the reverse orientation. Placement of the >—–< above the <—–> produced significantly greater illusion susceptibility, as predicted by the depth cue hypothesis. Females were more susceptible than males, but there were no interaction effects of sex with figure orientation or trials nor a main effect for trials. The results were interpreted as supporting an empiricistic explanation of the Mueller-Lyer illusion.

Evaluvation of artificially dried grass as a source of energy for sheep:II. The energy value of cocksfoot, timothy and two strains of rye-grass at varying stages of maturity

1964 ◽  
Vol 62 (3) ◽  
pp. 399-416 ◽  
Author(s):  
D. G. Armstrong
Keyword(s):  
The Other ◽  
Energy Value ◽  
The Third ◽  
Stages Of Growth ◽  
Rye Grass ◽  
Series Of Experiments ◽  
Different Levels

1. Four cuts of rye.grass S 23, three cuts each of cocksfoot S 37 and timothy S 48 and two cuts of rye-grass S 24 taken at different stages of growth and artificially (heat) dried were fed to mature sheep in a series of experiments designed to measure their value as sources of energy. The four cuts of rye-grass S 23 were each given to three sheep–two of the animals receiving it at five different levels of intake and the third at two levels. The other grasses were each given to four sheep at two levels of intake. The fasting heat productions of the sheep were measured at the beginning and end of the grass feeding periods. Altogether 152 experiments were made.

scholarly journals Cells and building structures. Part I.

2020 ◽  
Vol 11 (2) ◽  
pp. 123-134
Author(s):  
Géza Lámer
Keyword(s):  
Building Materials ◽  
Three Dimensional ◽  
Building Construction ◽  
The Other ◽  
List Type ◽  
Building Structures ◽  
Dimensional Boundary ◽  
Surface Construction ◽  
Different Levels ◽  
Dimensional Cell

AbstractThe rooms of each building can be interpreted as three-dimensional cells. Borders (sides, edges) of rooms can be identified as the two-, one-, or zero-dimensional boundary cells of the three dimensional cell. The building structures identified as two-, one-, or zero-dimensional cells can be modeled by distinguished geometrical forms, surface-, line-, and point-like bodies. In accordance with the latter, building materials (finished products) can also be considered as surface-, line-, and point-like bodies.The aim of the study is to create compliance between the cell elements and the building structures. It will be done at different levels:– interpretation of relationship between building construction and cells,– interpretation of relationship between building construction and selected bodies,– interpretation the loadbearing's structure using cells,– structure of the surface-construction and the cells,– interpretation building types using cells.In this paper (as part I) the first two items will be studied. The other three cases will be studied in another paper (as part II).

scholarly journals Effects of cortical damage on binocular depth perception

2016 ◽  
Vol 371 (1697) ◽  
pp. 20150254 ◽  
Author(s):  
Holly Bridge
Keyword(s):  
Depth Perception ◽  
Three Dimensional ◽  
Stereoscopic Vision ◽  
Temporal Lobectomy ◽  
Cortical Atrophy ◽  
Retinal Images ◽  
Posterior Cortical Atrophy ◽  
Retinal Input ◽  
The Brain ◽  
Binocular Depth

Stereoscopic depth perception requires considerable neural computation, including the initial correspondence of the two retinal images, comparison across the local regions of the visual field and integration with other cues to depth. The most common cause for loss of stereoscopic vision is amblyopia, in which one eye has failed to form an adequate input to the visual cortex, usually due to strabismus (deviating eye) or anisometropia. However, the significant cortical processing required to produce the percept of depth means that, even when the retinal input is intact from both eyes, brain damage or dysfunction can interfere with stereoscopic vision. In this review, I examine the evidence for impairment of binocular vision and depth perception that can result from insults to the brain, including both discrete damage, temporal lobectomy and more systemic diseases such as posterior cortical atrophy. This article is part of the themed issue ‘Vision in our three-dimensional world’.

scholarly journals Comparisons of Effective Fields of Two Ultra-Widefield Ophthalmoscopes, Optos 200Tx and Clarus 500

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Yoshitsugu Matsui ◽  
Atsushi Ichio ◽  
Asako Sugawara ◽  
Eriko Uchiyama ◽  
Hitomi Suimon ◽  
...  
Keyword(s):  
Retinal Imaging ◽  
Retinal Vessel ◽  
Effective Field ◽  
Eye Diseases ◽  
The Other ◽  
Retinal Images ◽  
Single Image ◽  
Depth Of Focus ◽  
Temporal Quadrant

Purpose. To compare the effective fields of the Optos 200Tx® and Clarus 500™, two ultra-widefield ophthalmoscopes, based on their ability to image branches of retinal vessel in the four retinal quadrants. Methods. Ninety retinal images from 90 patients with various eye diseases were studied. All patients had undergone 200° retinal imaging to obtain a single image of Optos (O) and the montage of two images of the Clarus (C). The highest number of traceable vessel branches in the four retinal quadrants was determined by two masked raters. An image was classified as “O > C” when the number of identifiable branch was greater in the Optos than the Clarus, as “O = C” when the number was equal and as “O < C” when the number was fewer in the Optos than the Clarus. Results. The appearance probability of “O > C” was significantly higher at the upper temporal quadrant than “O < C” (p<0.01 for both raters). In contrast, the appearance probability of “O < C” was significantly higher at the lower nasal quadrant than “O > C” (p<0.01 for both raters). There were no significant differences in the appearance probability between “O > C” and “O < C” at the other two retinal quadrants (p>0.50 for both raters). Conclusions. These results demonstrate that the effective field of views was different between the two devices at different retina quadrants. Further studies are needed to clarify possible factors such as artifacts by the eyelashes, differences in the depth of focus, motion of the device, and different locations of the images on the effective field of views.

The myth of visual depth cues V: Motion parallax

2021 ◽  
Author(s):  
Lydia Maniatis
Keyword(s):  
Depth Perception ◽  
Motion Parallax ◽  
Convincing Evidence ◽  
The Other ◽  
Visual Depth ◽  
Independent Factor ◽  
Depth Cues ◽  
Depth Cue

Motion parallax is conventionally described as a “depth cue.” Rogers &amp; Graham (1979) are credited with providing fairly convincing evidence for this view. Here, I argue that, just as in the case of the other so-called “depth cues,” the claim that “motion parallax” constitutes an independent factor supporting shape and depth perception is circular. Authors offering apparent demonstrations of this cue fail to properly distinguish between proximal and distal stimulus and overlook the fundamental confound of figural organization.

Effect of Expertise on 3D Force Application During the Starting Block Phase and Subsequent Steps in Sprint Running

2014 ◽  
Vol 30 (3) ◽  
pp. 390-400 ◽  
Author(s):  
Mitsuo Otsuka ◽  
Jae Kun Shim ◽  
Toshiyuki Kurihara ◽  
Shinsuke Yoshioka ◽  
Makoto Nokata ◽  
...  
Keyword(s):  
Reaction Force ◽  
Three Dimensional ◽  
The Other ◽  
Whole Body ◽  
Force Application ◽  
Maximum Effort ◽  
The Mean ◽  
Anterior Direction ◽  
Different Levels ◽  
Block Start

In sprinters with different levels of block acceleration, we investigated differences in their three-dimensional force application in terms of the magnitude, direction, and impulse of the ground reaction force (GRF) during the starting block phase and subsequent two steps. Twenty-nine participants were divided into three groups (well-trained, trained, and nontrained sprinters) based on their mean anteroposterior block acceleration and experience with a block start. The participants sprinted 10 m from a block start with maximum effort. Although the mean net resultant GRF magnitude did not differ between the well-trained and trained sprinters, the net sagittal GRF vector of the well-trained sprinters was leaned significantly further forward than that of the trained and nontrained sprinters during the starting block phase. In contrast, during the starting block phase and the subsequent steps, the transverse GRF vectors which cause the anteroposterior and mediolateral acceleration of the whole-body was directed toward the anterior direction more in the well-trained sprinters as compared with the other sprinters. Therefore, a more forward-leaning GRF vector and a greater anteroposterior GRF may particularly allow well-trained sprinters to generate a greater mean anteroposterior block acceleration than trained and nontrained sprinters.

Investigation of Errors in Perception of Stereoscopically Presented Virtual Object Locations in Real Display Space

1994 ◽  
Vol 38 (4) ◽  
pp. 250-254 ◽  
Author(s):  
Akira Utsumi ◽  
Paul Milgram ◽  
Haruo Takemura ◽  
Fumio Kishino
Keyword(s):  
Depth Perception ◽  
Binocular Disparity ◽  
Virtual Object ◽  
Perceptual Error ◽  
Virtual Objects ◽  
Object Locations ◽  
Depth Cue ◽  
Series Of Experiments ◽  
Image Blur ◽  
Source Of Error

This paper describes studies on perception of virtual object locations. It explores the behavior of some factors related to depth perception, especially the effect of inter-pupillary distance (IPD) mismatch and the interplay of image blur and binocular disparity. IPD mismatch (which is caused by errors in estimation of the parameter) results in a certain perceptual error of virtual objects' depth. Blur of images is also a source of error in depth representation. It was found, in some cases, to be a very strong depth cue. The results of a series of experiments conducted on IPD mismatch and image blur are also presented.

The Relationship between Apparent Depth and Disparity in Rivalrous-Texture Stereograms

Perception ◽  
1978 ◽  
Vol 7 (6) ◽  
pp. 661-678 ◽  
Author(s):  
John P Frisby ◽  
John E W Mayhew
Keyword(s):  
Random Noise ◽  
Significant Degree ◽  
Convincing Evidence ◽  
Apparent Depth ◽  
Depth Effect ◽  
Complex Stimuli ◽  
Depth Cue ◽  
Series Of Experiments ◽  
The Relationship ◽  
Binocular Depth

A series of experiments is reported on rivalrous-texture stereograms composed of narrow-band-filtered random noise. Experiment 1 found that the apparent depth—disparity function for such stereograms was different from that observed with similar but nonrivalrous stimuli. In particular, rivalrous divergent disparities produced the same depth as rivalrous zero disparity and this latter disparity itself produced a significant degree of protruding (i.e. ‘convergent’) depth in a certain type of rivalrous-texture stereogram. Free inspection was permitted and disparities were in the range 16 min convergent to 16 min divergent. Experiment 2 found no convincing evidence for reliable qualitative depth discriminations from tachistoscopic presentations of rivalrous-texture stereograms, using a forced-choice task requiring a discrimination between 16 min convergent and 16 min divergent conditions. This task was solved easily for equivalent nonrivalrous stimuli. Experiment 3 measured a hitherto unreported binocular depth effect, termed ‘paradepth’, which is produced by presenting a target in one field only. This effect appears to be a genuine binocular depth effect and not just the result of an ordinary monocular masking depth cue. The size of the depth effect was found to be a function of the width of the target. The overall conclusion derived from the series of experiments is that rivalrous-texture stereograms are complex stimuli capable of yielding curious and unexpected depth effects which are not readily explained in detail within any existing theoretical framework.

Three-dimensional image analysis and visualization in confocal light microscopy

1993 ◽  
Vol 51 ◽  
pp. 158-159
Author(s):  
J. K. Samarabandu ◽  
R. Acharya ◽  
D. R. Pareddy ◽  
P. C. Cheng
Keyword(s):  
Depth Perception ◽  
Computer Graphic ◽  
Three Dimensional ◽  
Cellular Organization ◽  
Data Set ◽  
Computational Burden ◽  
Interactive Operation ◽  
Cell Organization ◽  
Confocal Images ◽  
3D Digitization

In the study of cell organization in a maize meristem, direct viewing of confocal optical sections in 3D (by means of 3D projection of the volumetric data set, Figure 1) becomes very difficult and confusing because of the large number of nucleus involved. Numerical description of the cellular organization (e.g. position, size and orientation of each structure) and computer graphic presentation are some of the solutions to effectively study the structure of such a complex system. An attempt at data-reduction by means of manually contouring cell nucleus in 3D was reported (Summers et al., 1990). Apart from being labour intensive, this 3D digitization technique suffers from the inaccuracies of manual 3D tracing related to the depth perception of the operator. However, it does demonstrate that reducing stack of confocal images to a 3D graphic representation helps to visualize and analyze complex tissues (Figure 2). This procedure also significantly reduce computational burden in an interactive operation.

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