Visual depth perception

Abstract: Infants saw a textured light area expand and contract on a dark rear-projection screen. The texture elements (15 black dots) expanded and contracted radially from the center of the screen as though they were on a single surface (single-depth display) or independent (multiple-depth display). None of the texture elements was on a “collision” trajectory with the infant's face. The single-depth display elicited greater defensive reactions (blinking and backward head movement) on expansion than contraction trials in both 4- to 8-week-olds and 10- to 14-week-olds. A different group of 4- to 8-week-olds did not exhibit greater overall blinking or backward head movement to expansion versus contraction of the multiple-depth display. The findings suggest that young infants utilize flow field information to distinguish between approaching subjective surfaces and voids in the regions between sparse texture.

Abstract: The physical conditions of the display of single 2-D pictures, which produce images realistically, were studied by using the characteristics of the intake of the information for visual depth perception. Depth sensitivity, which is defined as the ratio of viewing distance to depth discrimination threshold, was introduced in order to evaluate the availability of various cues for depth perception: binocular parallax, motion parallax, accommodation, convergence, size, texture, brightness, and air-perspective contrast. The effects of binocular parallax in different conditions, the depth sensitivity of which is greatest at a distance of up to about 10 m, were studied with the new versatile stereoscopic display. From these results, four conditions to reinforce the perception of depth in single pictures were proposed, and these conditions are met by the old viewing devices and the new high-definition and wide television displays.

Abstract: The author presents a user interaction methodology based on a six degree of freedom interactive input device called the Spaceball. This methodology is geared for computer graphics applications that require items to be positioned or displaced in three-dimensional space in a purely visual and esthetic fashion. When the Spaceball device is used in conjunction with a common 2-D mouse-the Spaceball device held in one hand and the mouse in other-overall visual depth perception on traditional 2-D displays can be considerably enhanced by exploiting a technique called motion parallax, thereby promoting full three-dimensional user interaction. This paper focusses on the application of this methodology to sculpting highly irregular polygon mesh surfaces, such as character faces or any other surfaces of arbitrary shape. The Spaceball device is used to move the object being sculpted while the mouse carries out the picking and deformation work, all of which is projected onto the screen in real time. As case studies, three common operations in polygon mesh sculpting are described in detail (vertex creation, primitive selection and local surface deformations)

Abstract: to Section I.- 1 Form and Function in the Optical Structure of Bird Eyes.- 1.1 Introduction.- 1.2 The Bases of Diversity in Avian Eye Structure.- 1.3 Quantitative Descriptions of Eye Structures and Their Properties.- 1.4 Interpretations of Diversity.- 1.4.1 Shape and Size of Eyes.- 1.4.2 The Optical Design of Eyes.- 1.5 The Role of the Iris.- 1.5.1 Pupil Size and Image Brightness.- 1.5.2 Pupil Size and Image Quality.- 1.5.3 Pupil Size and Depth of Field.- 1.6 Visual Fields.- 1.6.1 Monocular Fields.- 1.6.2 Binocular and Panoramic Fields.- 1.6.3 Visual Fields and Amphibious Habits.- 1.7 Concluding Remarks.- References.- 2 Functional Accommodation in Birds.- 2.1 The Power and Precision of Accommodation as a Distance Cue.- 2.2 A Technique to Measure Accommodation in Unrestrained, Alert Birds.- 2.3 Mechanisms of Accommodation in Terrestrial Birds.- 2.3.1 Speed of Accommodation.- 2.3.2 Coupled and Uncoupled Accommodation and the Convergence of Information.- 2.4 Visual Guidance of Pecking Behaviour.- 2.5 Lower Field Myopia: an Adaptation That "Keeps the Ground in Focus"?.- 2.6 The Role of Accommodation in Judging Distances.- References.- 3 Binocular Depth Perception.- 3.1 Introduction.- 3.2 What Exactly is Stereopsis?.- 3.2.1 Retinal Disparity and Stereopsis.- 3.2.2 Types of Stereopsis.- 3.3 Stereopsis in Birds.- 3.3.1 Neural Mechanisms for Local Stereopsis in Birds.- 3.3.2 Behavioural Tests of Stereopsis in Birds.- 3.4 Binocular Vision and the Oculomotor System in Birds.- 3.4.1 The Position of the Binocular Field.- 3.4.2 The Visual Trident in Birds.- 3.4.3 Binocular Fixation and Fusion.- 3.4.4 Vergence Eye Movements.- 3.4.5 Stereoscopic Limits Imposed Through the Oculomotor System.- 3.5 Role of Binocular Vision in the Guidance of Avian Behaviour.- 3.5.1 Guidance of the Peck Movement.- 3.5.2 Dependence of Behaviour on the Frame of Reference.- 3.6 Conclusions.- References.- 4 Sound Cues to Distance: The Perception of Range.- 4.1 Introduction.- 4.2 Why Range?.- 4.3 Ranging Cues.- 4.4 The Experimental Evidence for Ranging Ability.- 4.5 Mechanisms of Degradation Perception.- 4.6 Ranging and Honesty.- 4.7 Some Developments of Ranging Studies.- 4.7.1 Ranging as a Component of Other Signalling Behaviour.- 4.7.2 Resolution of Ranging.- 4.8 Conclusions.- References.- 5 Avian Orientation: Multiple Sensory Cues and the Advantage of Redundancy.- 5.1 Theoretical Considerations.- 5.2 Compass Mechanisms and Their Interrelation.- 5.2.1 The Magnetic Compass of Birds.- 5.2.2 The Interrelation Between Magnetic Compass and Sun Compass.- 5.2.3 Directional Orientation at Night.- 5.2.4 Integrating Directional Orientation.- 5.3 Mechanism for Determining the Home Direction.- 5.3.1 Navigation by Route-Specific Information.- 5.3.2 Site-Specific Information - the Navigational "Map".- 5.3.3 Different Strategies Supplement Each Other.- 5.4 Determining the Migratory Direction.- 5.4.1 Reference Systems for the Migratory Direction.- 5.4.2 The Interrelation Between Celestial Rotation and the Magnetic Field During Ontogeny.- 5.5 Conclusion.- References.- to Section II.- 6 Neuroembryology of Motor Behaviour in Birds.- 6.1 Introduction.- 6.2 The Environment Within the Egg.- 6.3 Embryonic Motor Behaviours.- 6.3.1 Type I Embryonic Motility.- 6.3.2 Type II and Type III Embryonic Motility.- 6.4 Role of Sensory Information During Ongoing Embryonic Behaviours.- 6.4.1 What Sensory Information Is Available?.- 6.4.2 How Is Sensory Information Used?.- 6.5 Role of Sensory Input at Transitions in Behaviour.- 6.6 Role of Prior Sensory Input in Development of Later Behaviours.- 6.7 Conclusions.- References.- 7 Pre- and Postnatal Development of Wing-Flapping and Flight in Birds: Embryological, Comparative and Evolutionary Perspectives.- 7.1 Introduction.- 7.2 Prenatal Development of Spontaneous Wing-Flapping.- 7.3 Neural Basis of Embryonic Behaviour.- 7.4 Effect of Spontaneous Embryonic Behaviour on Muscle and Joint Development.- 7.5 Naturally Occurring Motor Neuron Death.- 7.6 Comparative Development of Wing-Flapping and Flight: Effects of Domestication.- 7.7 Experimental Studies of the Postnatal Development of Wing-Flapping and Flight.- 7.8 Bilateral Wing Coordination: Studies of Induced Bilateral Asymmetry.- 7.9 Development of Wing-Flapping and Flight in Dystrophic Chickens.- 7.10 Wing-Flapping in Flightless Birds: Evolutionary Insights.- 7.11 Centripetal Hypothesis of Neurobehavioural Evolution.- References.- 8 Development of Prehensile Feeding in Ring Doves (Streptopelia risoria): Learning Under Organismic and Task Constraints.- 8.1 Introduction.- 8.2 Thrusting and Grasping During Feeding in the Adult.- 8.3 Evidence for Plasticity and Skill in Adult Columbidae.- 8.4 The Transition from Dependent to Independent Feeding in the Ring Dove.- 8.5 Development of Pecking.- 8.5.1 Behavioural Analysis of the Development of Pecking.- 8.6 Behavioural Processes Underlying Development of Prehensile Feeding.- 8.7 The Viewpoint That Prehensile Feeding Is a Preorganized Response.- 8.8 Task Analysis.- 8.9 Summary.- References.- 9 Ingestive Behaviour and the Sensorimotor Control of the Jaw.- 9.1 Introduction.- 9.2 Ingestive Behaviour: Descriptive Analysis.- 9.3 Functional Considerations.- 9.4 Kinematic Analysis of Ingestive Jaw Movement Patterns.- 9.4.1 Kinematics of Drinking.- 9.4.2 Kinematics of Eating.- 9.5 Morphology and Myology of the Pigeon Jaw.- 9.6 Electromyographic Analysis of Ingestive Jaw Movements.- 9.6.1 Jaw Muscle Activity Patterns During Eating.- 9.6.2 Jaw Muscle Activity Patterns During Drinking.- 9.7 Response Topography and the Modulation of Jaw Movement Patterns.- 9.8 Conclusions.- References.- 10 Motor Organization of the Avian Head-Neck System.- 10.1 Introduction.- 10.2 Osteo-Muscular Design of the Avian Cervical Column.- 10.2.1 Osteology.- 10.2.2 Arthrology.- 10.2.3 Myology.- 10.3 Design Modifications of the Avian Cervical Column.- 10.3.1 Ligamentum Elasticum Cervicale.- 10.4 Patterning Head-Neck Movement and Motor Action.- 10.4.1 Postures: Minimal Flexion Model.- 10.4.2 Motion: Least Motion Model.- 10.4.3 Major Motion Principles.- 10.4.4 Motor Patterns.- 10.5 Control of Head-Neck Movements.- 10.5.1 Comparator Model of Head-Neck Control.- 10.5.2 Connections in the Central Nervous System.- 10.5.3 Network Control.- 10.6 Conclusions.- References.- to Section III.- 11 Course Control During Flight.- 11.1 Introduction: The Avian Flight Control System.- 11.2 Fundamentals of Avian Aeromechanics of Course Control.- 11.3 Head Stabilization and Head-Wing-Trunk Correlations During Slow Turning Flight.- 11.4 Head Deflection and Activity of Flight Control Muscles in the Flow-Stimulated Pigeon.- 11.5 Effects of Control Muscle Activity During Flight.- 11.6 Minimum Model of the Functional Organization of Course Control.- 11.7 The Extended Model: The Influence of Visceral and Vestibular Afferences on the Activity of Flight Control Muscles.- 11.8 Improvement of Head Stabilization by Airflow Stimuli.- References.- 12 The Analysis of Motion in the Visual Systems of Birds.- 12.1 Introduction.- 12.1.1 Local Motion, Figure-Ground Segregation and Camouflage.- 12.1.2 Trajectory and Spin.- 12.1.3 Self-Induced Motion.- 12.2 Object Motion in the Tectum and Tectofugal Pathway.- 12.2.1 Relative Motion.- 12.2.2 Figure-Ground Segregation Through Motion.- 12.2.3 Motion in Depth and Time to Collision.- 12.3 Visual Analysis of Self-Motion by the Accessory Optic System.- 12.3.1 Cardinal Directions of Optic Flow.- 12.3.2 Binocular Integration of Self-Induced Flow.- 12.4 Future Directions.- References.- 13 An Eye or Ear for Flying.- 13.1 Introduction.- 13.2 Flying by Eye.- 13.2.1 Stabilizing Vision.- 13.2.2 The Tau Function.- 13.2.3 Other Optical Specifications of ?(Z).- 13.2.4 More General Tau.- 13.2.5 Timing Interceptive Acts Under Acceleration.- 13.2.6 Action-Scaling Space.- 13.2.7 Theory of Control of Velocity of Approach.- 13.2.8 Experiments on Control of Velocity of Approach by Eye.- 13.3 Flying by Ear.- 13.3.1 Acoustic Taus.- 13.3.2 Experiments on Control of Velocity of Approach by Ear.- 13.4 Concluding Remarks.- References.- 14 Directional Hearing in Owls: Neurobiology, Behaviour and Evolution.- 14.1 Introduction.- 14.2 Bilateral Ear Asymmetry and Sound Localization in Owls.- 14.3 Neural Mechanisms for Sound Localization in Barn Owls.- 14.4 Comparative Physiology of Sound Localization Among the Owls.- 14.5 Evolution of Bilateral Ear Asymmetry.- 14.6 Future Directions.- References.- 15 Tuning of Visuomotor Coordination During Prey Capture in Water Birds.- 15.1 Introduction.- 15.2 Surface Plungers and Strikers.- 15.2.1 Light Reflection.- 15.2.2 Light Refraction.- 15.2.3 Surface Movement.- 15.2.4 Coping with Light Reflection and Surface Movement.- 15.3 Coping with Refraction: The Case of Herons and Egrets.- 15.3.1 Prey Capture by Little Egrets in the Field.- 15.3.2 Prey Capture by Reef Herons in Captivity.- 15.3.3 A Model for Coping with Light Refraction and Its Verification.- 15.3.4 Prey Capture in Cattle Egrets and Squacco Herons in Captivity.- 15.4 Visually Guided Prey Capture in Pied Kingfishers.- 15.4.1 Estimation of Prey Depth.- 15.4.2 Effect of Prey Movement on Capture Success.- 15.5 Concluding Remarks.- References.- 16 Multiple Sources of Depth Information: An Ecological Approach.- 16.1 Depth Perception and the Control of Behaviour.- 16.2 Models of Visual Depth Perception.- 16.2.1 The Hierarchical Model.- 16.2.2 The Heterarchical Model.- 16.2.3 The Integration of Multiple Depth Cues.- 16.3 Conclusions.- References.