Vision

2018 ◽  
Author(s):  
Nico Orlandi
Keyword(s):  
Visual Perception ◽  
Cognitive Science ◽  
Three Dimensional ◽  
Psychological State ◽  
Psychological Process ◽  
Two Dimensional ◽  
Vision Science ◽  
Psychological Theories ◽  
Black Surface ◽  
Obvious Manner

Why do things look to us as they do? This question, formulated by psychologist Kurt Koffka, identifies the main problematic of vision science. Consider looking at a black cat. We tend to see both the cat and its colour as the same at different times. Despite the ease with which this perception occurs, the process by which we perceive is fairly complex. The initial stimulation that gives rise to seeing, consists in a pattern of light that projects on the retina – a light-sensitive layer of the eye. The so-called ‘retinal image’ is a two-dimensional projection that does not correspond in any obvious manner to the way things look. It is not three-dimensional, coloured and shaped in a similar fashion to the objects of our experience. Indeed the light projected from objects is not just different from what we see, it is also both continuously changing and ambiguous. Because the cat moves around, the light it reflects changes from moment to moment. The cat’s projection on the retina correspondingly changes in size. We do not, however, see the cat as changing in size. We tend to see it as size-constant and uniformly coloured through time. How do we explain this constancy? Along similar lines, the cat’s white paws cause on the retina a patch of light that differs in intensity from the rest. This patch could also be caused by a change in illumination. A black surface illuminated very brightly can look like a white surface illuminated very dimly. This means that the light hitting the retina from the paws is underdetermined – it does not uniquely specify what is present. But, again, we tend to see the paws as consistently white. We do not see them as shifting from being white to being black, but illuminated brightly. How do we explain this stability? A central aim of theories of vision is to answer these questions. The science that attempts to address these queries is interdisciplinary. Traditionally, philosophical theories of vision have influenced psychological theories and vice versa. The collaboration between these disciplines eventually developed into what is now known as cognitive science. Cognitive science includes – in addition to philosophy and psychology – computer science, linguistics and neuroscience. Cognitive scientists aim primarily to understand the process by which we see. Philosophers are interested in this topic particularly as it connects to understanding the nature of our acquaintance with reality. Theories of vision differ along many dimensions. Giving a full survey is not possible in this entry. One useful difference is whether a theory presumes that visual perception involves a psychological process. Psychological theories of vision hold that in achieving perception – which is itself a psychological state – the organism uses other psychological material. Opponents of psychological theories prefer to make reference to physiological, mechanical and neurophysiological explanations.

scholarly journals Phenomenal Causality and Sensory Realism

i-Perception ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 204166952092703
Author(s):  
Kristof Meding ◽  
Sebastian A. Bruijns ◽  
Bernhard Schölkopf ◽  
Philipp Berens ◽  
Felix A. Wichmann
Keyword(s):  
Visual Perception ◽  
Three Dimensional ◽  
The Other ◽  
Two Dimensional ◽  
Perception Of Causality ◽  
Phenomenal Causality ◽  
Intuitive Physics ◽  
Three Dimensional Presentation ◽  
Cue Conflict ◽  
Motion Dynamics

One of the most important tasks for humans is the attribution of causes and effects in all wakes of life. The first systematical study of visual perception of causality—often referred to as phenomenal causality—was done by Albert Michotte using his now well-known launching events paradigm. Launching events are the seeming collision and seeming transfer of movement between two objects—abstract, featureless stimuli (“objects”) in Michotte’s original experiments. Here, we study the relation between causal ratings for launching events in Michotte’s setting and launching collisions in a photorealistically computer-rendered setting. We presented launching events with differing temporal gaps, the same launching processes with photorealistic billiard balls, as well as photorealistic billiard balls with realistic motion dynamics, that is, an initial rebound of the first ball after collision and a short sliding phase of the second ball due to momentum and friction. We found that providing the normal launching stimulus with realistic visuals led to lower causal ratings, but realistic visuals together with realistic motion dynamics evoked higher ratings. Two-dimensional versus three-dimensional presentation, on the other hand, did not affect phenomenal causality. We discuss our results in terms of intuitive physics as well as cue conflict.

Fictional Illustration Language with Reference to M. C. Escher and Istvan Orosz Examples

2017 ◽  
Vol 4 (11) ◽  
pp. 156-163
Author(s):  
Banu Bulduk Turkmen
Keyword(s):  
Visual Perception ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Technical Aspects ◽  
New Approaches ◽  
Alternative Approaches ◽  
The Subject ◽  
Three Dimensional Images

Alternative approaches in illustration language have constantly been developing in terms of material and technical aspects. Illustration languages also differ in terms of semantics and form. Differences in formal expressions for increasing the effect of the subject on the audience lead to diversity in the illustrations. M. C. Escher’s three-dimensional images to be perceived in a two-dimensional environment, together with mathematical and symmetry-oriented studies and the systematic formed by a numerical structure in its background, are associated with the notion of illustration in terms of fictional meaning. Istvan Orosz used the technique of anamorphosis and made it possible for people to see their perception abilities and visual perception sensitivities in different environments created by him. This study identifies new approaches and illustration languages based on the works of both artists, bringing an alternative proposition to illustration languages in terms of systematic sub-structure and fictional idea sketches. Keywords: Perception, illusion, illustration, fictional illustration, illustration languages, visual perception.

scholarly journals STRATEGIES TO EVALUATE THE VISIBILITY ALONG AN INDOOR PATH IN A POINT CLOUD REPRESENTATION

2017 ◽  
Vol IV-2/W4 ◽  
pp. 311-317 ◽  
Author(s):  
N. Grasso ◽  
E. Verbree ◽  
S. Zlatanova ◽  
M. Piras
Keyword(s):  
Visual Perception ◽  
Point Cloud ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Space Syntax ◽  
Point Of View ◽  
Indoor Environments ◽  
Two Dimensional ◽  
Visibility Graphs ◽  
Representations Of Space

Many research works have been oriented to the formulation of different algorithms for estimating the paths in indoor environments from three-dimensional representations of space. The architectural configuration, the actions that take place within it, and the location of some objects in the space influence the paths along which is it possible to move, as they may cause visibility problems. To overcome the visibility issue, different methods have been proposed which allow to identify the visible areas and from a certain point of view, but often they do not take into account the user’s visual perception of the environment and not allow estimating how much may be complicated to follow a certain path. In the field of space syntax and cognitive science, it has been attempted to describe the characteristics of a building or an urban environment by the isovists and visibility graphs methods; some numerical properties of these representations allow to describe the space as for how it is perceived by a user. However, most of these studies are directed to analyze the environment in a two-dimensional space. In this paper we propose a method to evaluate in a quantitative way the complexity of a certain path within an environment represented by a three-dimensional point cloud, by the combination of some of the previously mentioned techniques, considering the space visible from a certain point of view, depending on the moving agent (pedestrian , people in wheelchairs, UAV, UGV, robot).

scholarly journals Why does Necker Cube appear as the three-dimensional shape?

2020 ◽  
Author(s):  
Shohei Hidaka ◽  
Kohske Takahashi
Keyword(s):  
Visual Perception ◽  
Retinal Image ◽  
Dimensional Space ◽  
Necker Cube ◽  
3D Structure ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Adjoint Functors ◽  
Novel Theory ◽  
Multiple Structures

Visual perception, receiving a two-dimensional (2D) visual input, often constructs the three-dimensional (3D) perceptual image. Although there are generally multiple structures in the external world that give an equivalent two-dimensional retinal image, the perceptual process naturally and easily infer only one 3D structure as the solution. However, the following problems are not obvious at all: what kind of structure can be obtained as a 3D perceptual image from certain 2D information, and why do we get a three-dimensional perceptual image instead of a two-dimensional one. In the present study, we investigate this problem by untangling the Necker cube phenomenon, and propose a novel theory of three-dimensional visual perception from the viewpoint of the efficiency of information coding. Among the possible structures that can yield the 2D retinal image of the Necker cube, the structure of the typical three-dimensional perceptual image of the Necker cube maximizes the symmetry (in group theory). This maximization of symmetry is characterized by the pairs of adjoint functors (in category theory). Therefore, according to this proposed theory, "the Necker cube" in the three-dimensional space is perceived as the most efficient encoding of the two-dimensional retinal image.

scholarly journals A Quantitative Method for Estimation of Quality of Screens Color

2018 ◽  
pp. 39-46
Author(s):  
O. Kupko
Keyword(s):  
Visual Perception ◽  
Color Space ◽  
Three Dimensional ◽  
Dimensional Case ◽  
Two Dimensional ◽  
Color Spaces ◽  
Human Visual Perception ◽  
Insufficient Amount ◽  
History Of ◽  
The Difference

The history of the issue on creation of uniform color spaces is analyzed. It is noted that the calculations based on the results of spectral measurements do not adequately correspond to the human visual perception. For all existing color spaces, it has been proposed to create a uniform metric, a me­thod for determining the length, area and volume in the corresponding spaces, one that corresponds to the human visual perception. The metric is based on MacAdam ellipses, that is, on the threshold perception of the difference in colors. For each point of any color space (two or three measurements) is determined the area of space around each point, within which a person is not able to fix the difference in color. The area is characterized by either an ellipse (two-dimensional case) or an ellipsoid (three-dimensional case). To characterize an ellipse, it is necessary to have three parameters — two axes and the angle of slope. To characterize an ellipsoid, it is necessary to have five parameters — three axes and two angle of slope. The number of sections along a line, along a plane, or in a volume is a measure of length, a plane, or in a volume and sets a metric. The connection of the existing systems for determining color and visual perception of a person is carried out using scales. Scales associate the length, area or volume of any color system with a person’s visual perception. The scale depends on the point of space and the direction in which the movement takes place. As a result, a large number of scales (more than the number of colors, because it is necessary to know the angles of inclination of the ellipses) are needed, which must be agreed by the international community. To use this amount of data and for the corresponding calculations, it is necessary to have an agreed international calculation procedure. It is established, that as a result of the development of computing technology, a large amount of data and a large amount of computation are not a significant obstacle. The obstacle is an insufficient amount of consistent data, that is, it is necessary to perform additional measurements and approvals to determine the areas of space around each point of the color space within which a person is not able to fix the difference in color. A schematic diagram of the measurements and the equipment with the help of which it is possible to carry out the corresponding measurements are proposed. Estimates of the greatest labour intensity of such works are carried out. It is determined what is the most important part of these works is possible to carry out within a few years. For two-dimensional spaces (x, y and u, v), using the results of the classical work of McAdam, we determined the scales for connecting the lengths and areas in these spaces with the visual perception of the human eye. The directions in which the scales are largest or smallest are determined. For these two directions there are given scales that relate the distances and areas of the spaces (x,y and u,v) with the human visual perception. It is noted, that the work on creating the metrics has a clear phased structure, some parts of the work, i.e.: the development of software and programming, the development of stabilized radiation sources, the development of comparing tools and experimental research can be carried out independently. Conclusions and suggestions are made.

scholarly journals On three dimensional perceptions in the visual age

2015 ◽  
Vol 5 (1) ◽  
pp. 10
Author(s):  
Melek Sahan
Keyword(s):  
Visual Perception ◽  
Visual Arts ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Related Literature ◽  
Visual Arts Education ◽  
Starting Point ◽  
The Subject ◽  
High Level ◽  
Document Review

Aim of the study is to examine the values of the three dimensional perception and collect information about that. Starting point is the observation of differences in two and three dimensional perception abilities of individuals having education in visual arts. It has been observed that some students, who have high level of competency in two dimensional perception, do not have the same competency in three dimensional perception. This is considered important since it creates two and three dimensional perceptions and differences of expression between them. We tried to emphasize the importance of the subject particularly in terms of visual arts education in the current visual age. The study is a document review. In this study we addressed the characteristics of the age we are living in, perception, visual perception, and two and three dimensional perception. We summarized the differences in visual perception and included three dimensional comprehension. By examining the related literature, we came to the conclusion that the two and three dimensional perception processes and their requirements are different.   Keywords: sculpture, three dimensional perceptions, visual perception, visual age.

High Resolution Microscopy of Multi-Layered Biological Crystals

1982 ◽  
Vol 40 ◽  
pp. 80-83
Author(s):  
H.A. Cohen ◽  
T.W. Jeng ◽  
W. Chiu
Keyword(s):  
High Resolution ◽  
Low Dose ◽  
Three Dimensional ◽  
Data Interpretation ◽  
Two Dimensional ◽  
Biological Objects ◽  
Density Maps ◽  
Density Map ◽  
Complex Crystal ◽  
High Resolution Microscopy

This tutorial will discuss the methodology of low dose electron diffraction and imaging of crystalline biological objects, the problems of data interpretation for two-dimensional projected density maps of glucose embedded protein crystals, the factors to be considered in combining tilt data from three-dimensional crystals, and finally, the prospects of achieving a high resolution three-dimensional density map of a biological crystal. This methodology will be illustrated using two proteins under investigation in our laboratory, the T4 DNA helix destabilizing protein gp32*I and the crotoxin complex crystal.

Instrumentation For Quantitative Microscopy

1977 ◽  
Vol 35 ◽  
pp. 206-209
Author(s):  
B. Ralph ◽  
A.R. Jones
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Automatic Data ◽  
Phase Volume Fraction ◽  
Statistical Confidence ◽  
Resultant Data ◽  
Automatic Data Collection ◽  
Third Dimension ◽  
Evolution Of Microstructure

In all fields of microscopy there is an increasing interest in the quantification of microstructure. This interest may stem from a desire to establish quality control parameters or may have a more fundamental requirement involving the derivation of parameters which partially or completely define the three dimensional nature of the microstructure. This latter categorey of study may arise from an interest in the evolution of microstructure or from a desire to generate detailed property/microstructure relationships. In the more fundamental studies some convolution of two-dimensional data into the third dimension (stereological analysis) will be necessary.In some cases the two-dimensional data may be acquired relatively easily without recourse to automatic data collection and further, it may prove possible to perform the data reduction and analysis relatively easily. In such cases the only recourse to machines may well be in establishing the statistical confidence of the resultant data. Such relatively straightforward studies tend to result from acquiring data on the whole assemblage of features making up the microstructure. In this field data mode, when parameters such as phase volume fraction, mean size etc. are sought, the main case for resorting to automation is in order to perform repetitive analyses since each analysis is relatively easily performed.

A linearity test for thick specimens imaged by HVEM over a 180° angular range

1991 ◽  
Vol 49 ◽  
pp. 552-553
Author(s):  
Yu Liu
Keyword(s):  
Phase Contrast ◽  
Three Dimensional ◽  
Angular Range ◽  
Two Dimensional ◽  
Back Projection ◽  
Line Integral ◽  
Exponential Law ◽  
Transmission Electron ◽  
Absorption Law ◽  
Linearity Test

The image obtained in a transmission electron microscope is the two-dimensional projection of a three-dimensional (3D) object. The 3D reconstruction of the object can be calculated from a series of projections by back-projection, but this algorithm assumes that the image is linearly related to a line integral of the object function. However, there are two kinds of contrast in electron microscopy, scattering and phase contrast, of which only the latter is linear with the optical density (OD) in the micrograph. Therefore the OD can be used as a measure of the projection only for thin specimens where phase contrast dominates the image. For thick specimens, where scattering contrast predominates, an exponential absorption law holds, and a logarithm of OD must be used. However, for large thicknesses, the simple exponential law might break down due to multiple and inelastic scattering.

An Image Reconstruction System Applied to High Voltage Microscopy

1975 ◽  
Vol 33 ◽  
pp. 292-293
Author(s):  
D. E. Johnson
Keyword(s):  
High Voltage ◽  
Prior Information ◽  
Block Diagram ◽  
Three Dimensional ◽  
Real Space ◽  
Two Dimensional ◽  
Efficient Manner ◽  
Fourier Methods ◽  
Tilt Series ◽  
Methods Of Reconstruction

Increased specimen penetration; the principle advantage of high voltage microscopy, is accompanied by an increased need to utilize information on three dimensional specimen structure available in the form of two dimensional projections (i.e. micrographs). We are engaged in a program to develop methods which allow the maximum use of information contained in a through tilt series of micrographs to determine three dimensional speciman structure.In general, we are dealing with structures lacking in symmetry and with projections available from only a limited span of angles (±60°). For these reasons, we must make maximum use of any prior information available about the specimen. To do this in the most efficient manner, we have concentrated on iterative, real space methods rather than Fourier methods of reconstruction. The particular iterative algorithm we have developed is given in detail in ref. 3. A block diagram of the complete reconstruction system is shown in fig. 1.

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