Illusory Volumes from Conformation

Perception ◽  
1998 ◽  
Vol 27 (8) ◽  
pp. 977-992 ◽  
Author(s):  
Peter Ulric Tse
Keyword(s):  
Visual System ◽  
Surface Curvature ◽  
Local Surface ◽  
Supporting Surface ◽  
Illusory Contours ◽  
Flat Surfaces ◽  
Contour Surface ◽  
Inferential Processing ◽  
Global Surface

The purpose of this paper is to offer demonstrations of ‘illusory volumes’ in the spirit of the illusory flat surfaces described by Kanizsa. These demonstrations of illusory volumes exploit a new cue to the recovery of surface curvature from ambiguous images: conformation. In assuming conformation, the visual system assumes that the surface of a volume conforms to the curvature of its neighboring, underlying, or supporting surface, in the absence of image cues to the contrary. Demonstrations that exploit the assumption of conformation provide several insights into the nature of the inferential processing that underlies contour, surface, and volume formation. In particular, these demonstrations imply that the visual system does not calculate local surface curvature, illusory contours, or occlusion relationships before it analyzes global surface relationships.

Amodal Completion and the Perception of Depth without Binocular Correspondence

Perception ◽  
10.1068/p3305 ◽  
2002 ◽  
Vol 31 (9) ◽  
pp. 1037-1045 ◽  
Author(s):  
Benoit A Bacon ◽  
Pascal Mamassian
Keyword(s):  
Amodal Completion ◽  
Correspondence Problem ◽  
Illusory Contours ◽  
Binocular Matching ◽  
Partially Occluded ◽  
Global Surface

Half-occlusions and illusory contours have recently been used to show that depth can be perceived in the absence of binocular correspondence and that there is more to stereopsis than solving the correspondence problem. In the present study we show a new way for depth to be assigned in the absence of binocular correspondence, namely amodal completion. Although an occluder removed all possibility of direct binocular matching, subjects consistently assigned the correct depth (convexity or concavity) to partially occluded ‘folded cards’ stimuli. Our results highlight the importance of more global, surface-based processes in stereopsis.

scholarly journals Perception and misperception of surface opacity

2017 ◽  
Vol 114 (52) ◽  
pp. 13840-13845 ◽  
Author(s):  
Phillip J. Marlow ◽  
Juno Kim ◽  
Barton L. Anderson
Keyword(s):  
Visual System ◽  
Fundamental Problem ◽  
Surface Orientation ◽  
The Body ◽  
Local Surface ◽  
Significant Information ◽  
Scene Structure ◽  
The Relationship ◽  
Opaque Surface ◽  
Insight Into

A fundamental problem in extracting scene structure is distinguishing different physical sources of image structure. Light reflected by an opaque surface covaries with local surface orientation, whereas light transported through the body of a translucent material does not. This suggests the possibility that the visual system may use the covariation of local surface orientation and intensity as a cue to the opacity of surfaces. We tested this hypothesis by manipulating the contrast of luminance gradients and the surface geometries to which they belonged and assessed how these manipulations affected the perception of surface opacity/translucency. We show that (i) identical luminance gradients can appear either translucent or opaque depending on the relationship between luminance and perceived 3D surface orientation, (ii) illusory percepts of translucency can be induced by embedding opaque surfaces in diffuse light fields that eliminate the covariation between surface orientation and intensity, and (iii) illusory percepts of opacity can be generated when transparent materials are embedded in a light field that generates images where surface orientation and intensity covary. Our results provide insight into how the visual system distinguishes opaque surfaces and light-permeable materials and why discrepancies arise between the perception and physics of opacity and translucency. These results suggest that the most significant information used to compute the perceived opacity and translucency of surfaces arise at a level of representation where 3D shape is made explicit.

scholarly journals ALIGNING METHOD OF STRUCTURES DURING INSTALLATION IN VERTICAL PLANE

2020 ◽  
Vol 5 (443) ◽  
pp. 63-70
Author(s):  
Goltsev Anatoly Grigoryevich, ◽  
◽  
Kurmangaliyev Timur Bolatovich, ◽  
Sherov Karibek Tagayevich, ◽  
Sikhimbayev Muratbay Ryzdikbayevich, ◽  
...  
Keyword(s):  
Visual System ◽  
Research Methods ◽  
Vertical Plane ◽  
Plumb Line ◽  
Building Structures ◽  
Flat Surfaces ◽  
Straight Line ◽  
Wall Panels ◽  
Laser Devices ◽  
Principle Of Similarity

This article presents the results of the research methods of structures aligning during installation in the vertical plane. The analysis and research of existing methods of structures alignment in the vertical plane, used in the conditions of enterprises engaged in the installation of metal tanks. The results of the research showed that the applied alignment methods in the vertical plane have some drawbacks, in particular, after aligning, additional calculations are required. And also for alignment of sliding timbering, columns and wall panels use some theodolites, including vertical allotment. Laser devices and theodolites with visual system were also investigated. However, all the methods considered with the use of these devices are quite time-consuming and a significant number of tools and equipment are used. A device is proposed to control the shape and location of flat surfaces using the principle of similarity of triangles allowing obtaining a straight line of intersection of lasers in space parallel to the plumb line. Developed devices are cheap, easy to use and manufacture. With the use of the proposed technique, there is no need to use several working and expensive devices. The developed devices can significantly reduce the alignment time of building structures in the vertical and horizontal planes.

Optimization of the Modified Yoshida Buckling Test to Investigate the Influence of Curvature

2016 ◽  
Vol 1140 ◽  
pp. 67-74
Author(s):  
Sven Schreyer ◽  
Wolfram Volk
Keyword(s):  
Sheet Thickness ◽  
Surface Curvature ◽  
Drawing Process ◽  
Simple Test ◽  
Local Surface ◽  
Test Form ◽  
Compressive Stresses ◽  
Factors Influencing ◽  
Test Geometry ◽  
Buckling Test

During deep drawing process compressive stresses are induced in the sheet metal, which can cause undesirable wrinkling. On the other hand a high sheet thickness and high local surface curvature counteract the wrinkling tendency by stabilizing the blank. To investigate these factors influencing the wrinkling initiation experimentally, a modified and the requirements customized test form based on a simple test geometry, the so called Yoshida buckling test, is created. This enables to take into account surface curvature in the region of instability.

scholarly journals Flat surfaces machining by the magneto-abrasive method with permanent magnet end-type heads 3. The influence of the types of the working heads on the effectiveness of the magneto-abrasive machining

2021 ◽  
Vol 5 (1) ◽  
pp. 97-102
Author(s):  
Victor Maiboroda ◽  
Dmytro Dzhulii ◽  
Andrii Zelinko ◽  
Aleksey Burikov
Keyword(s):  
Permanent Magnet ◽  
Magnetic Induction ◽  
Feed Rate ◽  
Machining Process ◽  
Abrasive Machining ◽  
Technological Parameters ◽  
Supporting Surface ◽  
Flat Surfaces ◽  
Torus Type ◽  
Kinetics Of

Investigations of the magneto-abrasive machining (MAM) process of ferromagnetic flat surfaces by three types of end heads were carried out. The nature of the change in the magnitude of the magnetic induction in the working zones was determined. The influence of technological parameters of the machining process was investigated, such as the feed rate of the working heads, the frequency of their rotation about their axis, the size of the working gaps on the change in the parameters of the microroughness of the machined surfaces - Sa, Sp, Sv, the frequency distribution of heights microroughness and size of the supporting surface of the profile. It was shown that the level of roughness achieved after MAM is practically the same and does not exceed, under rational conditions of the MAM process, the values Sa = 0.05-0.07 μm, Sp = 0.2 μm and Sv = 0.39 μm with the only difference that the MAM process by the heads of the "brush-half of torus" type are being realized with increased productivity, especially in terms of reducing waviness and individual elements of the heredity of machining, determined by such factors as depth and feed rate during milling. The kinetics of the formation of a microprofile of surfaces is shown under various technological conditions of the MAM process.

The Discriminability of Local Surface Structure

Perception ◽  
1996 ◽  
Vol 25 (4) ◽  
pp. 381-398 ◽  
Author(s):  
J Farley Norman ◽  
James T Todd
Keyword(s):  
Visual System ◽  
Surface Structure ◽  
Human Visual System ◽  
Binocular Disparity ◽  
Qualitative Difference ◽  
Surface Orientation ◽  
Sources Of Information ◽  
Local Surface ◽  
Projected Image ◽  
Image Separation

The ability of observers to discriminate depth and orientation differences between separated local regions on object surfaces was examined. The objects were defined by many optical sources of information simultaneously, including shading, texture, motion, and binocular disparity. Despite the full-cue nature of the displays, the observers' performance was relatively poor, with Weber fractions ranging from 10% to 40%. The Weber fractions were considerably lower for discriminations of surface-orientation differences than for similar discriminations of depth differences. The ability of observers to discriminate surface-orientation differences was approximately invariant over the separation of the regions in the projected image. In contrast, the ability to discriminate depth differences was highly influenced by the amount of image separation. This qualitative difference between the perception of depth intervals and surface-orientation differences suggests that knowledge of depths and orientations may be represented separately within the human visual system.

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