DOCSLIB.ORG

Neural Mechanisms of Binocular Motion in Depth Perception

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Neural Mechanisms of Binocular Motion in Depth Perception Neural mechanisms of binocular motion in depth perception Milena Kaestner PhD University of York Psychology May 2018 1 2 Abstract Motion in depth (MID) can be cued by two binocular sources of information. These are changes in retinal disparity over time (changing disparity, CD), and binocular opponent velocity vectors (inter-ocular velocity difference, IOVD). This thesis presents a series of psychophysical and fMRI experiments investigating the neural pathways supporting the perception of CD and IOVD. The first two experiments investigated how CD and IOVD mechanisms draw on information encoded in the magnocellular, parvocellular and koniocellular pathways. The chromaticity of CD and IOVD-isolating stimuli was manipulated to bias activity in these three pathways. Although all stimulus types and chromaticities supported a MID percept, fMRI revealed an especially dominant koniocellular contribution to the IOVD mechanism. Because IOVD depends on eye-specific velocity signals, experiment three sought to identify an area in the brain that encodes motion direction and eye of origin information. Classification and multivariate pattern analysis techniques were applied to fMRI data, but no area where both types of information were present simultaneously was identified. Results suggested that IOVD mechanisms inherit eye-specific information from V1. Finally, experiment four asked whether activity elicited by CD and IOVD stimuli could also be modulated by an attentional task where participants were asked to detect changes in MID or local contrast. fMRI activity was strongly modulated by attentional state, and activity in motion-selective areas was predictive of whether participants correctly identified the change in CD or IOVD MID. This suggests that these areas contain populations of neurons that are crucial for detecting, and behaviourally responding to, both types of MID. The work presented in this thesis detail a thorough investigation of the neural pathways that underlie the computation of CD and IOVD cues to MID. 3 List of Contents Abstract……………………………………………………………………………………………….. 3 List of Contents……………………………………………………………………………………… 4 List of Tables……………………………………………………………………………………..….. 8 List of Figures……………………………………………………………………………………….. 9 Acknowledgements……………………………………………………………………………….. 12 Author’s declaration………………………………………………………………………………..13 Chapter 1. Introduction ................................................................................................... 15 1.1 Fundamentals of visual processing: retina to cortex ........................................ 16 1.1.1 Retinal physiology ........................................................................................... 16 1.1.2 The primary visual pathways: retina to V1 ....................................................... 18 1.2 Binocularity and stereopsis................................................................................. 22 1.3 Stereograms and kinematograms: the separate study of depth and motion ... 24 1.4 Binocular cues to motion in depth perception ................................................... 26 1.4.1 Changing disparity........................................................................................... 26 1.4.2 Inter-ocular velocity difference ......................................................................... 27 1.4.3 Isolating CD and IOVD cues: stimulus design ................................................. 29 1.4.4 Evidence for the CD mechanism ..................................................................... 31 1.4.5 Evidence for the IOVD mechanism .................................................................. 32 1.4.6 Relative contributions of CD and IOVD to 3D motion perception ..................... 34 1.4.7 Spatiotemporal tuning of binocular MID mechanisms ...................................... 35 1.5 Neural encoding of 3D motion ............................................................................. 36 1.5.1 Motion and depth encoding ............................................................................. 36 1.5.2 Cortical and subcortical routes into MT ............................................................ 37 1.5.3 Evidence for MID processing in MT ................................................................. 39 1.6 Summary and outstanding questions ................................................................. 43 1.7 Outline of this thesis ............................................................................................ 44 1.8 Supplementary information ................................................................................. 45 Chapter 2. Chromatic disparity and velocity cues contribute to motion in depth perception ........................................................................................................................ 47 2.1 Abstract ................................................................................................................ 47 2.2 Introduction .......................................................................................................... 48 2.2.1 Binocular cues to motion in depth .................................................................... 48 2.2.2 Chromatic cues to motion perception .............................................................. 50 2.3 Methods ................................................................................................................ 51 4 2.3.1 Participants ...................................................................................................... 51 2.3.2 Materials .......................................................................................................... 52 2.3.3 Stimulus design ............................................................................................... 52 2.3.4 CD stimuli ........................................................................................................ 54 2.3.5 IOVD stimuli .................................................................................................... 55 2.3.6 Participant training ........................................................................................... 55 2.3.7 Procedure ........................................................................................................ 56 2.4 Results .................................................................................................................. 57 2.4.1 Contrast thresholding....................................................................................... 57 2.4.2 Coherence thresholding ................................................................................... 58 2.4.3 Achromatic masking ........................................................................................ 61 2.5 Discussion ............................................................................................................ 62 2.5.1 Chromatic input to MID mechanisms ............................................................... 62 2.5.2 Properties of the CD and IOVD mechanisms ................................................... 64 2.5.3 Conclusions ..................................................................................................... 64 Chapter 3. Distinct response patterns for achromatic and S-cone inputs to cortical motion in depth mechanisms ............................................................................................ 67 3.1 Abstract ................................................................................................................. 67 3.2 Introduction .......................................................................................................... 68 3.3 Materials and methods ......................................................................................... 70 3.3.1 Participants ...................................................................................................... 70 3.3.2 Apparatus ........................................................................................................ 71 3.3.3 Stimulus design ............................................................................................... 72 3.3.4 CD stimulus ..................................................................................................... 73 3.3.5 CD control stimulus ......................................................................................... 74 3.3.6 IOVD stimulus ................................................................................................. 74 3.3.7 IOVD control stimulus ...................................................................................... 75 3.3.8 Isoluminance setting ........................................................................................ 75 3.3.9 MRI parameters ............................................................................................... 76 3.3.10 fMRI procedure and task ................................................................................. 77 3.3.11 Mapping regions of interest ............................................................................. 79 3.3.12 Whole-brain analysis ....................................................................................... 81 3.3.13 ROI analysis .................................................................................................... 82 3.4 Results .................................................................................................................. 83 3.4.1 Whole-brain results .........................................................................................
Load more

Recommended publications
  • Motion-In-Depth Perception and Prey Capture in the Praying Mantis Sphodromantis Lineola
    © 2019. Published by The Company of Biologists Ltd | Journal of Experimental Biology (2019) 222, jeb198614. doi:10.1242/jeb.198614 RESEARCH ARTICLE Motion-in-depth perception and prey capture in the praying mantis Sphodromantis lineola Vivek Nityananda1,*, Coline Joubier1,2, Jerry Tan1, Ghaith Tarawneh1 and Jenny C. A. Read1 ABSTRACT prey as they come near. Just as with depth perception, several cues Perceiving motion-in-depth is essential to detecting approaching could contribute to the perception of motion-in-depth. or receding objects, predators and prey. This can be achieved Two of the motion-in-depth cues that have received the most using several cues, including binocular stereoscopic cues such attention in humans are binocular: changing disparity and as changing disparity and interocular velocity differences, and interocular velocity differences (IOVDs) (Cormack et al., 2017). monocular cues such as looming. Although these have been Stereoscopic disparity refers to the difference in the position of an studied in detail in humans, only looming responses have been well object as seen by the two eyes. This disparity reflects the distance to characterized in insects and we know nothing about the role of an object. Thus as an object approaches, the disparity between the stereoscopic cues and how they might interact with looming cues. We two views changes. This changing disparity cue suffices to create a used our 3D insect cinema in a series of experiments to investigate perception of motion-in-depth for human observers, even in the the role of the stereoscopic cues mentioned above, as well as absence of other cues (Cumming and Parker, 1994).
    [Show full text]
  • Stereoscopic Viewing Enhances Visually Induced Motion Sickness
    Behrang Keshavarz* Stereoscopic Viewing Enhances Heiko Hecht Department of General Visually Induced Motion Sickness Experimental Psychology but Sound Does Not Johannes Gutenberg-University 55099 Mainz, Germany Abstract Optic flow in visual displays or virtual environments often induces motion sickness (MS). We conducted two studies to analyze the effects of stereopsis, background sound, and realism (video vs. simulation) on the severity of MS and related feelings of immersion and vection. In Experiment 1, 79 participants watched either a 15-min-long video clip taken during a real roller coaster ride, or a precise simulation of the same ride. Additionally, half of the participants watched the movie in 2D, and the other half in 3D. MS was measured using the Simulator Sickness Questionnaire (SSQ) and the Fast Motion Sickness Scale (FMS). Results showed a significant interaction for both variables, indicating highest sickness scores for the real roller coaster video presented in 3D, while all other videos provoked less MS and did not differ among one another. In Experiment 2, 69 subjects were exposed to a video captured during a bicycle ride. Viewing mode (3D vs. 2D) and sound (on vs. off) were varied between subjects. Response measures were the same as in Experiment 1. Results showed a significant effect of stereopsis; MS was more severe for 3D presentation. Sound did not have a significant effect. Taken together, stereoscopic viewing played a crucial role in MS in both experiments. Our findings imply that stereoscopic videos can amplify visual dis- comfort and should be handled with care. 1 Introduction Over the past decades, the technological progress in entertainment sys- tems has grown rapidly.
    [Show full text]
  • Durham E-Theses
    Durham E-Theses Validating Stereoscopic Volume Rendering ROBERTS, DAVID,ANTHONY,THOMAS How to cite: ROBERTS, DAVID,ANTHONY,THOMAS (2016) Validating Stereoscopic Volume Rendering, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/11735/ 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 Validating Stereoscopic Volume Rendering David Roberts A Thesis presented for the degree of Doctor of Philosophy Innovative Computing Group School of Engineering and Computing Sciences Durham University United Kingdom 2016 Dedicated to My Mom and Dad, my sisters, Sarah and Alison, my niece Chloe, and of course Keeta. Validating Stereoscopic Volume Rendering David Roberts Submitted for the degree of Doctor of Philosophy 2016 Abstract The evaluation of stereoscopic displays for surface-based renderings is well established in terms of accurate depth perception and tasks that require an understanding of the spatial layout of the scene.
    [Show full text]
  • Stereoscopic 3D Videos and Panoramas Stereoscopic 3D Videos and Panoramas
    Christian Richardt Stereoscopic 3D Videos and Panoramas Stereoscopic 3D videos and panoramas 1. Capturing and displaying stereo 3D videos 2. Viewing comfort considerations 3. Editing stereo 3D videos (research papers) 4. Creating stereo 3D panoramas 2017-08-03 Christian Richardt – Stereoscopic 3D Videos and Panoramas 2 Stereo camera rigs Parallel Converged (‘toed-in’) 2017-08-03 Christian Richardt – Stereoscopic 3D Videos and Panoramas 3 Stereo camera rigs Parallel Converged (‘toed-in’) Kreylos Kreylos Oliver Oliver 2012 2012 © ©2012 Oliver 2017-08-03 Christian Richardt – Stereoscopic 3D Videos and Panoramas 4 Computational stereo 3D camera system et al./ACM et Computational stereo camera system with programmable control loop S. Heinzle, P. Greisen, D. Gallup, C. Chen, D. Saner, A. Smolic, A. Burg, W. Matusik & M. Gross Heinzle ACM Transactions on Graphics (SIGGRAPH), 2011, 30(4), 94:1–10 2011 © 2017-08-03 Christian Richardt – Stereoscopic 3D Videos and Panoramas 5 Commercial stereo 3D projection Polarised projection Wavelength multiplexing e.g. RealD 3D, MasterImage 3D e.g. Dolby 3D 3.0 - SA - BY - Commons/CC Wilkinson/Sound and Vision and Wilkinson/Sound NK, 3dnatureguy/Wikimedia Raoul Raoul ©2011 ©2011 Scott © 2017-08-03 Christian Richardt – Stereoscopic 3D Videos and Panoramas 6 Medium-scale stereo 3D displays Active shutter glasses Autostereoscopy e.g. NVIDIA 3D Vision, 3D TVs 3.0 - SA - BY - ©2011 ©2011 MTBS3D/NVIDIA /Wikimedia Commons/CC /Wikimedia Cmglee © 2017-08-03 Christian Richardt – Stereoscopic 3D Videos and Panoramas 7 Other stereo 3D displays Head-mounted displays (HMDs) Anaglyph stereo e.g. HTC Vive, Oculus Rift, Google Cardboard e.g. red cyan glasses, ColorCode 3-D, Inficolor 3D ©2016 HTC Corporation ©2016 HTC Taringa 2016 2016 © 2017-08-03 Christian Richardt – Stereoscopic 3D Videos and Panoramas 8 Cinema 3D Narrow angular range that spans a single seat et al.
    [Show full text]
  • A Method for the Assessment of the Quality of Stereoscopic 3D Images Raluca Vlad
    A Method for the Assessment of the Quality of Stereoscopic 3D Images Raluca Vlad To cite this version: Raluca Vlad. A Method for the Assessment of the Quality of Stereoscopic 3D Images. Signal and Image Processing. Université de Grenoble, 2013. English. tel-00925280v2 HAL Id: tel-00925280 https://tel.archives-ouvertes.fr/tel-00925280v2 Submitted on 10 Jan 2014 (v2), last revised 28 Feb 2014 (v3) HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. THÈSE pour obtenir le grade de DOCTEUR DE L’UNIVERSITÉ DE GRENOBLE Spécialité : Signal, Image, Parole, Télécommunications (SIPT) Arrêté ministériel : 7 août 2006 Présentée par Mlle Raluca VLAD Thèse dirigée par Mme Anne GUÉRIN-DUGUÉ et Mme Patricia LADRET préparée au sein du laboratoire Grenoble - Images, Parole, Signal, Automatique (GIPSA-lab) dans l’école doctorale d’Électronique, Électrotechnique, Automatique et Traitement du signal (EEATS) Une méthode pour l’évaluation de la qualité des images 3D stéréoscopiques Thèse soutenue publiquement le 2 décembre 2013, devant le jury composé de : Patrick LE CALLET
    [Show full text]
  • Perceiving Self-Motion in Depth: the Role of Stereoscopic Motion and Changing-Size Cues
    Perception & Psychophysics 1996,58 (8), JJ68-JJ76 Perceiving self-motion in depth: The role of stereoscopic motion and changing-size cues STEPHEN PALMISANO University ofNew South Wales, Kensington, New South Wales, Australia During self-motions, different patterns of optic flow are presented to the left and right eyes. Previ­ ous research has, however, focused mainly on the self-motion information contained in a single pattern of optic flow. The present experiments investigated the role that binocular disparity plays in the visual perception of self-motion, showing that the addition of stereoscopic cues to optic flow significantly im­ proves forward linear vection in central vision. Improvements were also achieved by adding changing­ size cues to sparse (but not dense) flow patterns. These findings showedthat assumptions in the head­ ing literature that stereoscopic cues facilitate self-motion only when the optic flow has ambiguous depth ordering do not apply to vection. Rather, it was concluded that both stereoscopic and changing­ size cues provide additional motion-in-depth information that is used in perceiving self-motion. Ofall the senses known to be involved in self-motion During self-motions, different patterns of optic flow perception-the vestibular, auditory, somatosensory, pro­ are presented to the left and right eyes (due to the sepa­ prioceptive, and visual systems-visionappears to play the ration ofthe eyes and their different angles ofregard; see dominant role (Benson, 1990; Howard, 1982). This is Figure 1). Theorists have, however, generally focused only demonstrated by the fact that compelling illusions of on the motion-perspective information contained in a sin­ self-motion can be induced by visual information alone.
    [Show full text]
  • Visual 3D Motion Acuity Predicts Discomfort in 3D Stereoscopic Environments Q ⇑ Brian Allen 1, Taylor Hanley 1, Bas Rokers ,1, C
    Entertainment Computing 13 (2016) 1–9 Contents lists available at ScienceDirect Entertainment Computing journal homepage: ees.elsevier.com/entcom Visual 3D motion acuity predicts discomfort in 3D stereoscopic environments q ⇑ Brian Allen 1, Taylor Hanley 1, Bas Rokers ,1, C. Shawn Green 1,2 Department of Psychology, University of Wisconsin – Madison, United States article info abstract Article history: A major hindrance in the popularization of 3D stereoscopic media is the high rate of motion sickness Received 9 July 2015 reported during use of VR technology. While the exact factors underlying this phenomenon are unknown, Revised 30 November 2015 the dominant framework for explaining general motion sickness (‘‘cue-conflict” theory) predicts that Accepted 9 January 2016 individual differences in sensory system sensitivity should be correlated with experienced discomfort Available online 14 January 2016 (i.e. greater sensitivity will allow conflict between cues to be more easily detected). To test this hypoth- esis, 73 participants successfully completed a battery of tests to assess sensitivity to visual depth cues as Keywords: well as a number of other basic visual functions. They then viewed a series of 3D movies using an Oculus Virtual reality Rift 3D head-mounted display. As predicted, individual differences, specifically in sensitivity to dynamic Simulator sickness 3D motion visual cues to depth, were correlated with experienced levels of discomfort. These results suggest a Cue-conflict theory number of potential methods to reduce VR-related motion sickness in the future. Ó 2016 Published by Elsevier B.V. 1. Introduction myriad, one issue that consistently appears in both anecdotal accounts, and in the few scientific reports on the topic, is that Just four to five years ago, stereo 3D technology was being stereo 3D environments make a significant proportion of viewers hailed as the next major development in entertainment media.
    [Show full text]
  • The Stereoscopic Cinema: from Film to Digital Projection
    TECHNICAL PAPER The Stereoscopic Cinema: From Film to Digital Projection By Lenny Lipton Lenny Lipton A noteworthy improvement in the projection of stereoscopic moving awaited the invention of commercial- images is taking place; the image is clear and easy to view. Moreover, the quality sheet polarizers by Edwin setup of projection is simplified, and requires no tweaking for continued Land, who applied the material to 3 performance at a high-quality level. The new system of projection relies stereoscopic eyewear. on the Texas Instruments Digital Micromirror Device (DMD), and the The Norling approach became the model for the theatrical motion pic- basis for this paper is the Christie Digital Mirage 5000 projector and ture stereoscopic boom of the early StereoGraphics selection devices, CrystalEyes and the ZScreen. 1950s. In those days theaters had two projectors in the booth for changeover from reel to reel, provid- tereoscopic cinema has not problems of the past to better appreci- ing an opportunity to modify the Sbecome an accepted part of the ate the virtues of the improvement setup to run interlocked left and right neighborhood theatrical experience described. projectors (Fig. 1). because the technology hasn’t been Polarization Efforts It may well be that problems in the perfected to the point where it is satis- projection booth bear the major share fying for either the exhibitor or the The first successful (and influential) of responsibility for this short-lived viewer. However, the medium has commercial use of full-color stereo- effort. Polaroid researchers Jones and become widely accepted in theme scopic movie projection in the U.S.
    [Show full text]
  • The Role of Stereoscopic Motion and Changing-Size Cues
    University of Wollongong Research Online Faculty of Social Sciences - Papers Faculty of Arts, Social Sciences & Humanities 1996 Perceiving self-motion in depth: the role of stereoscopic motion and changing-size cues Stephen Palmisano University of Wollongong, [email protected] Follow this and additional works at: https://ro.uow.edu.au/sspapers Part of the Education Commons, and the Social and Behavioral Sciences Commons Recommended Citation Palmisano, Stephen, "Perceiving self-motion in depth: the role of stereoscopic motion and changing-size cues" (1996). Faculty of Social Sciences - Papers. 1142. https://ro.uow.edu.au/sspapers/1142 Research Online is the open access institutional repository for the University of Wollongong. For further information contact the UOW Library: [email protected] Perceiving self-motion in depth: the role of stereoscopic motion and changing- size cues Abstract During self-motions different patterns of optic flow are presented to the left and right eyes. Previous research has, however, focussed mainly on the self-motion information contained in a single pattern of optic flow. The current studies investigated the role that binocular disparity plays in the visual perception of self-motion, showing that the addition of stereoscopic cues to optic flow significantly improves forwards linear vection in central vision. Improvements were also achieved by adding changing-size cues to sparse (but not dense) flow patterns. These findings showed that assumptions in the heading literature that stereoscopic cues only facilitate self-motion when the optic flow has ambiguous depth ordering, do not apply to vection. Rather, it was concluded that both stereoscopic and changing-size cues provide additional motion in depth information which is used in perceiving self-motion.
    [Show full text]
  • Stereo from Shading
    Eurographics Symposium on Rendering - Experimental Ideas & Implementations (2015) J. Lehtinen and D. Nowrouzezahrai (Editors) Stereo from Shading Alexandre Chapiro1;2, Carol O’Sullivan3, Wojciech Jarosz 2, Markus Gross1;2, Aljoscha Smolic2, 1 ETH Zurich, 2 Disney Research Zurich , 3 Disney Research LA A A B B Figure 1: Stereo from Shading: the anaglyph image on the right is assembled from a single view (center) with no parallax disparity, but with different shading (left), producing a 3D impression. The inset represents the difference between eye renders. Abstract A We present a new methodB for creating and enhancing the stereoscopic 3D (S3D) sensation without using the parallax disparity between an image pair. S3D relies on a combination of cues to generate a feeling of depth, but only a few of these cues can easily be modified within a rendering pipeline without significantly changing the content. We explore one such cue—shading stereopsis—whwhich to date has not been exploited for 3D rendering. By changing only the shading of objects between the left and right eye renders, we generate a noticeable increase in perceived depth. This effect can be used to create depth when applied to flat images, and to enhance depth when applied to shallow depth S3D images. Our method modifies the shading normals of objects or materials, such that it can be flexibly and selectively applied in complex scenes with arbitrary numbers and types of lights and indirect illumination. Our results show examples of rendered stills and video, as well as live action footage. Categories and Subject Descriptors (according to ACM CCS): Hardware Architecture [I.3.1]: Three-dimensional displays—; Computer Graphics [I.3.3]: Three-Dimensional Graphics and Realism—Display Algorithms; Image Processing and Computer Vision [I.4.8]: Scene Analysis—Stereo; 1.
    [Show full text]
  • PROCESSES in BIOLOGICAL VISION: Including
    PROCESSES IN BIOLOGICAL VISION: including, ELECTROCHEMISTRY OF THE NEURON This material is excerpted from the full β-version of the text. The final printed version will be more concise due to further editing and economical constraints. A Table of Contents and an index are located at the end of this paper. James T. Fulton Vision Concepts [email protected] April 30, 2017 Copyright 2004 James T. Fulton Dynamics of Vision 7- 1 7 Dynamics of Vision 1 The dynamics of the visual process have not been assembled and presented in a cogent manner within the academic vision literature. On the other hand, several authors have presented cogent descriptions applicable to the clinical level. The material assembled by Salmon at Northeastern State University2 in Oklahoma is exemplary (but superficial for the purpose at hand). The dynamics associated with the mechanism of interpreting symbols and character groups, called reading, has not been presented at all. Only the major eye movements related to reading have been studied in significant detail. Even the adaptation characteristic of vision as a function of illumination level has not been presented from a theoretical perspective, and the empirical data has not been analyzed in sufficient detail to provide a coherent understanding of the process. When assembled as a group, the mechanisms and processes associated with forming the chromophores of vision provide a new, interesting and unique perspective on the formation of those chromophores. This Chapter will assemble the pertinent data with respect to a variety of processes where their dynamic aspects are crucial to the visual function. 7.1 Characteristics & Dynamics of Retinoids in the body The following material is based on extensive empirical investigations that were largely lacking with regard to any contiguous theory of what the goals of the mechanisms involved were from the perspective of the visual modality.
    [Show full text]
  • Processes in Biological Vision
    PROCESSES IN BIOLOGICAL VISION: including, ELECTROCHEMISTRY OF THE NEURON This material is excerpted from the full β-version of the text. The final printed version will be more concise due to further editing and economical constraints. A Table of Contents and an index are located at the end of this paper. James T. Fulton Vision Concepts [email protected]/vision April 30, 2017 Copyright 2000 James T. Fulton Environment & Coordinates 2- 1 2. Environment, Coordinate Reference System and First Order Operation 1 The beginning of wisdom is to call things by their right names. - Chinese Proverb The process of communication involves a mutual agreement on the meaning of words. - Charley Halsted, 1993 [xxx rationalize azure versus aqua before publishing ] The environment of the eye can be explored from several points of view; its radiation environment, its thermo- mechanical environment, its energy supply environment and its output signal environment. To discuss the operation of the eye in such environments, establishing certain coordinate systems, functional relationships and methods of notation is important. That is the purpose of this chapter. The reader is referred to the original source for more details on the environment and the coordinate systems. Extensive references are provided for this purpose. Details relative to the various functional operations in vision will be explored in the chapters to follow. Because of the unique integration of many processes by the photoreceptor cells of the retina, which are explored individually in different chapters, a brief section is included here to coordinate this range of material. 2.1 Physical Environment The study of the visual system requires exploring a great many parameters from a variety of perspectives.
    [Show full text]