Stereopsis Prof. Fred Kingdom Department Ophthalmology

Total Page：16

File Type：pdf, Size：1020Kb

Stereopsis Prof. Fred Kingdom Department Ophthalmology Reading Chapter in Adler’s on binocular vision Lecture PPT on http://www.mcgill.ca/mvr/resident/ Seeing Depth Part I Cues to depth Part II Stereopsis Part III Clinical tests for stereopsis !! !! Part I. Cues to depth Position in field of view! Occlusion/Interposition! Object size! Cues to depth Texture gradients! Linear perspective! Shading! Texture gradients/Perspective Atmospheric: Occlusion/Interposition Blueing with distance Depth from shading Kurt Wenner Part II. Stereopsis -Definition - Retinal disparity - Horopters - Stereoacuity - Stereoscopes and anaglyphs - Form-from-stereopsis - Correspondence problem - Autostereograms !! definition……….. Stereopsis is the means by which we determine the relative depth of objects by virtue of the fact that our two eyes view the world from a slightly different angle. ! Retinal! disparity! !! more definitions……. Retinal disparity is the difference in angle subtended by the image of an object betwen the two eyes, relative to fixation. Stereoacuity is the minimal detectable stereoscopic depth in units of disparity. Normal = 5-15 secs of arc; best is 2 secs. Fusion limit is the largets disparity that can be fused Diplopia is the experience of double vision Stereoacuity: Normal: 5-15 arc secs of arc; best is 2 secs. Fusion Limit (Panum’s limit): 1.5 - 20 arc mins Development: Abrupt onset of stereopsis at 3-5 months Horopters Wheatstone stereoscope Perceived Principle of anaglyphs image F Screen F Perceived image filter Crossed disparity Uncrossed disparity Effect of disparity Random-dot stereogram Figural stereogram Random-dot Stereogram ‘global’ stereopsis Figural Stereogram ‘local’ stereopsis Figural stereogram Random-dot-stereogram ‘Local’ stereopsis ‘Global’ stereopsis ‘False-target’ or stereo-correspondence problem Autostereogram Autostereogram Clinical aspects Development: Abrupt onset of stereopsis at 3-5 months Critical periods: Infancy 6-10 months Childhood 10 months – 9 years Clinical aspects Stereoanomaly: Persons with a selective deficit in either crossed or uncrossed disparities (Richards, 1971), apparently unlinked to amblyopia Amblyopia: Strabismus and Anisometropia Tests for binocular vision and stereopsis Worth 4 dot: Test for binocular function Stereo Fly test: Test for ‘local’ stereopsis Stereo Butterfly: Test for ‘global’ stereopsis TNO: Test for ‘global’ stereopsis Randot E: Test for ‘global’ stereopsis .

Copy Link

Recommended publications

CS 534: Computer Vision Stereo Imaging Outlines
CS 534 A. Elgammal Rutgers University CS 534: Computer Vision Stereo Imaging Ahmed Elgammal Dept of Computer Science Rutgers University CS 534 – Stereo Imaging - 1 Outlines • Depth Cues • Simple Stereo Geometry • Epipolar Geometry • Stereo correspondence problem • Algorithms CS 534 – Stereo Imaging - 2 1 CS 534 A. Elgammal Rutgers University Recovering the World From Images We know: • 2D Images are projections of 3D world. • A given image point is the projection of any world point on the line of sight • So how can we recover depth information CS 534 – Stereo Imaging - 3 Why to recover depth ? • Recover 3D structure, reconstruct 3D scene model, many computer graphics applications • Visual Robot Navigation • Aerial reconnaissance • Medical applications The Stanford Cart, H. Moravec, 1979. The INRIA Mobile Robot, 1990. CS 534 – Stereo Imaging - 4 2 CS 534 A. Elgammal Rutgers University CS 534 – Stereo Imaging - 5 CS 534 – Stereo Imaging - 6 3 CS 534 A. Elgammal Rutgers University Motion parallax CS 534 – Stereo Imaging - 7 Depth Cues • Monocular Cues – Occlusion – Interposition – Relative height: the object closer to the horizon is perceived as farther away, and the object further from the horizon is perceived as closer. – Familiar size: when an object is familiar to us, our brain compares the perceived size of the object to this expected size and thus acquires information about the distance of the object. – Texture Gradient: all surfaces have a texture, and as the surface goes into the distance, it becomes smoother and finer. – Shadows – Perspective – Focus • Motion Parallax (also Monocular) • Binocular Cues • In computer vision: large research on shape-from-X (should be called depth from X) CS 534 – Stereo Imaging - 8 4 CS 534 A.
[Show full text]
Interacting with Autostereograms
See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/336204498 Interacting with Autostereograms Conference Paper · October 2019 DOI: 10.1145/3338286.3340141 CITATIONS READS 0 39 5 authors, including: William Delamare Pourang Irani Kochi University of Technology University of Manitoba 14 PUBLICATIONS 55 CITATIONS 184 PUBLICATIONS 2,641 CITATIONS SEE PROFILE SEE PROFILE Xiangshi Ren Kochi University of Technology 182 PUBLICATIONS 1,280 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Color Perception in Augmented Reality HMDs View project Collaboration Meets Interactive Spaces: A Springer Book View project All content following this page was uploaded by William Delamare on 21 October 2019. The user has requested enhancement of the downloaded file. Interacting with Autostereograms William Delamare∗ Junhyeok Kim Kochi University of Technology University of Waterloo Kochi, Japan Ontario, Canada University of Manitoba University of Manitoba Winnipeg, Canada Winnipeg, Canada [email protected] [email protected] Daichi Harada Pourang Irani Xiangshi Ren Kochi University of Technology University of Manitoba Kochi University of Technology Kochi, Japan Winnipeg, Canada Kochi, Japan [email protected] [email protected] [email protected] Figure 1: Illustrative examples using autostereograms. a) Password input. b) Wearable e-mail notification. c) Private space in collaborative conditions. d) 3D video game. e) Bar gamified special menu. Black elements represent the hidden 3D scene content. ABSTRACT practice. This learning effect transfers across display devices Autostereograms are 2D images that can reveal 3D content (smartphone to desktop screen). when viewed with a specific eye convergence, without using CCS CONCEPTS extra-apparatus.
[Show full text]
Stereoscopic Label Placement
Linköping Studies in Science and Technology Dissertations, No. 1293 Stereoscopic Label Placement Reducing Distraction and Ambiguity in Visually Cluttered Displays Stephen Daniel Peterson Department of Science and Technology Linköping University SE-601 74 Norrköping, Sweden Norrköping, 2009 Stereoscopic Label Placement: Reducing Distraction and Ambiguity in Visually Cluttered Displays Copyright © 2009 Stephen D. Peterson [email protected] Division of Visual Information Technology and Applications (VITA) Department of Science and Technology, Linköping University SE-601 74 Norrköping, Sweden ISBN 978-91-7393-469-5 ISSN 0345-7524 This thesis is available online through Linköping University Electronic Press: www.ep.liu.se Printed by LiU-Tryck, Linköping, Sweden 2009 Abstract With increasing information density and complexity, computer displays may become visually cluttered, adversely affecting overall usability. Text labels can significantly add to visual clutter in graphical user interfaces, but are generally kept legible through specific label placement algorithms that seek visual separation of labels and other ob- jects in the 2D view plane. This work studies an alternative approach: can overlap- ping labels be visually segregated by distributing them in stereoscopic depth? The fact that we have two forward-looking eyes yields stereoscopic disparity: each eye has a slightly different perspective on objects in the visual field. Disparity is used for depth perception by the human visual system, and is therefore also provided by stereoscopic 3D displays to produce a sense of depth. This work has shown that a stereoscopic label placement algorithm yields user per- formance comparable with existing algorithms that separate labels in the view plane. At the same time, such stereoscopic label placement is subjectively rated significantly less disturbing than traditional methods.
[Show full text]
Stereopsis and Stereoblindness
Exp. Brain Res. 10, 380-388 (1970) Stereopsis and Stereoblindness WHITMAN RICHARDS Department of Psychology, Massachusetts Institute of Technology, Cambridge (USA) Received December 20, 1969 Summary. Psychophysical tests reveal three classes of wide-field disparity detectors in man, responding respectively to crossed (near), uncrossed (far), and zero disparities. The probability of lacking one of these classes of detectors is about 30% which means that 2.7% of the population possess no wide-field stereopsis in one hemisphere. This small percentage corresponds to the probability of squint among adults, suggesting that fusional mechanisms might be disrupted when stereopsis is absent in one hemisphere. Key Words: Stereopsis -- Squint -- Depth perception -- Visual perception Stereopsis was discovered in 1838, when Wheatstone invented the stereoscope. By presenting separate images to each eye, a three dimensional impression could be obtained from two pictures that differed only in the relative horizontal disparities of the components of the picture. Because the impression of depth from the two combined disparate images is unique and clearly not present when viewing each picture alone, the disparity cue to distance is presumably processed and interpreted by the visual system (Ogle, 1962). This conjecture by the psychophysicists has received recent support from microelectrode recordings, which show that a sizeable portion of the binocular units in the visual cortex of the cat are sensitive to horizontal disparities (Barlow et al., 1967; Pettigrew et al., 1968a). Thus, as expected, there in fact appears to be a physiological basis for stereopsis that involves the analysis of spatially disparate retinal signals from each eye. Without such an analysing mechanism, man would be unable to detect horizontal binocular disparities and would be "stereoblind".
[Show full text]
Algorithms for Single Image Random Dot Stereograms
Displaying 3D Images: Algorithms for Single Image Random Dot Stereograms Harold W. Thimbleby,† Stuart Inglis,‡ and Ian H. Witten§* Abstract This paper describes how to generate a single image which, when viewed in the appropriate way, appears to the brain as a 3D scene. The image is a stereogram composed of seemingly random dots. A new, simple and symmetric algorithm for generating such images from a solid model is given, along with the design parameters and their influence on the display. The algorithm improves on previously-described ones in several ways: it is symmetric and hence free from directional (right-to-left or left-to-right) bias, it corrects a slight distortion in the rendering of depth, it removes hidden parts of surfaces, and it also eliminates a type of artifact that we call an “echo”. Random dot stereograms have one remaining problem: difficulty of initial viewing. If a computer screen rather than paper is used for output, the problem can be ameliorated by shimmering, or time-multiplexing of pixel values. We also describe a simple computational technique for determining what is present in a stereogram so that, if viewing is difficult, one can ascertain what to look for. Keywords: Single image random dot stereograms, SIRDS, autostereograms, stereoscopic pictures, optical illusions † Department of Psychology, University of Stirling, Stirling, Scotland. Phone (+44) 786–467679; fax 786–467641; email [email protected] ‡ Department of Computer Science, University of Waikato, Hamilton, New Zealand. Phone (+64 7) 856–2889; fax 838–4155; email [email protected]. § Department of Computer Science, University of Waikato, Hamilton, New Zealand.
[Show full text]
Visual Secret Sharing Scheme with Autostereogram*
Visual Secret Sharing Scheme with Autostereogram* Feng Yi, Daoshun Wang** and Yiqi Dai Department of Computer Science and Technology, Tsinghua University, Beijing, 100084, China Abstract. Visual secret sharing scheme (VSSS) is a secret sharing method which decodes the secret by using the contrast ability of the human visual system. Autostereogram is a single two dimensional (2D) image which becomes a virtual three dimensional (3D) image when viewed with proper eye convergence or divergence. Combing the two technologies via human vision, this paper presents a new visual secret sharing scheme called (k, n)-VSSS with autostereogram. In the scheme, each of the shares is an autostereogram. Stacking any k shares, the secret image is recovered visually without any equipment, but no secret information is obtained with less than k shares. Keywords: visual secret sharing scheme; visual cryptography; autostereogram 1． Introduction In 1979, Blakely and Shamir[1-2] independently invented a secret sharing scheme to construct robust key management scheme. A secret sharing scheme is a method of sharing a secret among a group of participants. In 1994, Naor and Shamir[3] firstly introduced visual secret sharing * Supported by National Natural Science Foundation of China (No. 90304014) ** E-mail address: [email protected] (D.S.Wang) 1 scheme in Eurocrypt’94’’ and constructed (k, n)-threshold visual secret sharing scheme which conceals the original data in n images called shares. The original data can be recovered from the overlap of any at least k shares through the human vision without any knowledge of cryptography or cryptographic computations. With the development of the field, Droste[4] provided a new (k, n)-VSSS algorithm and introduced a model to construct the (n, n)-combinational threshold scheme.
[Show full text]
Chromostereo.Pdf
ChromoStereoscopic Rendering for Trichromatic Displays Le¨ıla Schemali1;2 Elmar Eisemann3 1Telecom ParisTech CNRS LTCI 2XtremViz 3Delft University of Technology Figure 1: ChromaDepth R glasses act like a prism that disperses incoming light and induces a differing depth perception for different light wavelengths. As most displays are limited to mixing three primaries (RGB), the depth effect can be signiﬁcantly reduced, when using the usual mapping of depth to hue. Our red to white to blue mapping and shading cues achieve a signiﬁcant improvement. Abstract The chromostereopsis phenomenom leads to a differing depth per- ception of different color hues, e.g., red is perceived slightly in front of blue. In chromostereoscopic rendering 2D images are produced that encode depth in color. While the natural chromostereopsis of our human visual system is rather low, it can be enhanced via ChromaDepth R glasses, which induce chromatic aberrations in one Figure 2: Chromostereopsis can be due to: (a) longitunal chro- eye by refracting light of different wavelengths differently, hereby matic aberration, focus of blue shifts forward with respect to red, offsetting the projected position slightly in one eye. Although, it or (b) transverse chromatic aberration, blue shifts further toward might seem natural to map depth linearly to hue, which was also the the nasal part of the retina than red. (c) Shift in position leads to a basis of previous solutions, we demonstrate that such a mapping re- depth impression. duces the stereoscopic effect when using standard trichromatic dis- plays or printing systems. We propose an algorithm, which enables an improved stereoscopic experience with reduced artifacts.
[Show full text]
Binocular Vision
BINOCULAR VISION Rahul Bhola, MD Pediatric Ophthalmology Fellow The University of Iowa Department of Ophthalmology & Visual Sciences posted Jan. 18, 2006, updated Jan. 23, 2006 Binocular vision is one of the hallmarks of the human race that has bestowed on it the supremacy in the hierarchy of the animal kingdom. It is an asset with normal alignment of the two eyes, but becomes a liability when the alignment is lost. Binocular Single Vision may be defined as the state of simultaneous vision, which is achieved by the coordinated use of both eyes, so that separate and slightly dissimilar images arising in each eye are appreciated as a single image by the process of fusion. Thus binocular vision implies fusion, the blending of sight from the two eyes to form a single percept. Binocular Single Vision can be: 1. Normal – Binocular Single vision can be classified as normal when it is bifoveal and there is no manifest deviation. 2. Anomalous - Binocular Single vision is anomalous when the images of the fixated object are projected from the fovea of one eye and an extrafoveal area of the other eye i.e. when the visual direction of the retinal elements has changed. A small manifest strabismus is therefore always present in anomalous Binocular Single vision. Normal Binocular Single vision requires: 1. Clear Visual Axis leading to a reasonably clear vision in both eyes 2. The ability of the retino-cortical elements to function in association with each other to promote the fusion of two slightly dissimilar images i.e. Sensory fusion. 3. The precise co-ordination of the two eyes for all direction of gazes, so that corresponding retino-cortical element are placed in a position to deal with two images i.e.
[Show full text]
From Stereogram to Surface: How the Brain Sees the World in Depth
Spatial Vision, Vol. 22, No. 1, pp. 45–82 (2009) © Koninklijke Brill NV, Leiden, 2009. Also available online - www.brill.nl/sv From stereogram to surface: how the brain sees the world in depth LIANG FANG and STEPHEN GROSSBERG ∗ Department of Cognitive and Neural Systems, Center for Adaptive Systems and Center of Excellence for Learning in Education, Science, and Technology, Boston University, 677 Beacon St., Boston, MA 02215, USA Received 19 April 2007; accepted 31 August 2007 Abstract—When we look at a scene, how do we consciously see surfaces infused with lightness and color at the correct depths? Random-Dot Stereograms (RDS) probe how binocular disparity between the two eyes can generate such conscious surface percepts. Dense RDS do so despite the fact that they include multiple false binocular matches. Sparse stereograms do so even across large contrast-free regions with no binocular matches. Stereograms that define occluding and occluded surfaces lead to surface percepts wherein partially occluded textured surfaces are completed behind occluding textured surfaces at a spatial scale much larger than that of the texture elements themselves. Earlier models suggest how the brain detects binocular disparity, but not how RDS generate conscious percepts of 3D surfaces. This article proposes a neural network model that predicts how the layered circuits of visual cortex generate these 3D surface percepts using interactions between visual boundary and surface representations that obey complementary computational rules. The model clarifies how interactions between layers 4, 3B and 2/3A in V1 and V2 contribute to stereopsis, and proposes how 3D perceptual grouping laws in V2 interact with 3D surface filling-in operations in V1, V2 and V4 to generate 3D surface percepts in which figures are separated from their backgrounds.
[Show full text]
The Effects of 3D Movies to Our Eyes
Bridge This Newsletter aims to promote communication between schools and Sept 2013 Issue No.60 Published by the Student Health Service, Department of Health the Student Health Service of the Department of Health Editiorial Continuous improvement in technology has made 3D film and 3D television programme available. It rewards our life with more advance visual experience. But at the same time, we should be aware of the risk factors of 3D films when we are enjoying them. In this issue, we would like to provide some information on “Evolution of Binocular vision”, “Principal of 3D Films” and “Common Side Effects of Viewing 3D Films”. Most important, we would like to enhance readers’ awareness on taking necessary precautions. We hope our readers could enjoy 3D films as well as keep our eyes healthy. Editorial Board Members: Dr. HO Chun-luen, David, Ms. LAI Chiu-wah, Phronsie, Ms. CHAN Shuk-yi, Karindi, Ms. CHOI Choi-fung, Ms. CHAN Kin-pui Tel : 2349 4212 / 3163 4600 Fax : 2348 3968 Website : http://www.studenthealth.gov.hk 1 Health Decoding Optometrist: Lam Kin Shing, Wallace Cheung, Rita Wong, Roy Wong Introduction 3D movies are becoming more popular nowadays. The brilliant box record of the 3D movie “Avatar” has led to the fast development of 3D technology. 3D technology not only affects the film industry but also extends to home televisions, video game products and many other goods. It certainly enriches our visual perception and gives us entertainment. Evolution of Binocular vision Mammals have two eyes. Some prey animals, e.g. rabbits, buffaloes, and sheep, have their two eyes positioned on opposite sides of their heads to give the widest possible field of view.
[Show full text]
Construction of Autostereograms Taking Into Account Object Colors and Its Applications for Steganography
Construction of Autostereograms Taking into Account Object Colors and its Applications for Steganography Yusuke Tsuda Yonghao Yue Tomoyuki Nishita The University of Tokyo ftsuday,yonghao,[email protected] Abstract Information on appearances of three-dimensional ob- jects are transmitted via the Internet, and displaying objects q plays an important role in a lot of areas such as movies and video games. An autostereogram is one of the ways to represent three- dimensional objects taking advantage of binocular paral- (a) SS-relation (b) OS-relation lax, by which depths of objects are perceived. In previous Figure 1. Relations on an autostereogram. methods, the colors of objects were ignored when construct- E and E indicate left and right eyes, re- ing autostereogram images. In this paper, we propose a L R spectively. (a): A pair of points on the screen method to construct autostereogram images taking into ac- and a single point on the object correspond count color variation of objects, such as shading. with each other. (b): A pair of points on the We also propose a technique to embed color informa- object and a single point on the screen cor- tion in autostereogram images. Using our technique, au- respond with each other. tostereogram images shown on a display change, and view- ers can enjoy perceiving three-dimensional object and its colors in two stages. Color information is embedded in we propose an approach to take into account color variation a monochrome autostereogram image, and colors appear of objects, such as shading. Our approach assign slightly when the correct color table is used.
[Show full text]
Durham E-Theses
Durham E-Theses Stereoscopic 3D Technologies for Accurate Depth Tasks: A Theoretical and Empirical Study FRONER, BARBARA How to cite: FRONER, BARBARA (2011) Stereoscopic 3D Technologies for Accurate Depth Tasks: A Theoretical and Empirical Study, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/3324/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk 2 Stereoscopic 3D Technologies for Accurate Depth Tasks: A Theoretical and Empirical Study by Barbara Froner A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy School of Engineering and Computing Sciences Durham University United Kingdom Copyright °c 2011 by Barbara Froner Abstract Stereoscopic 3D Technologies for Accurate Depth Tasks: A Theoretical and Empirical Study Barbara Froner In the last decade an increasing number of application ¯elds, including medicine, geoscience and bio-chemistry, have expressed a need to visualise and interact with data that are inherently three-dimensional.
[Show full text]