Acknowledgments ix
Introduction xi
Chapter 1. Principles of Depth and Shape Perception 1
1.1. Function of the eye 1
1.2. Depth perception without stereoscopy 2
1.2.1. Monocular cues 2
1.2.2. Proprioceptive cues 7
1.3. Depth perception through stereoscopic vision 9
1.4. Perception of inclinations and curves 10
1.4.1. Perception of inclination and obliqueness 10
1.4.2. Perception of curves 14
1.5. Artificial stereoscopic vision 22
Chapter 2. Technological Elements 25
2.1. Taking a picture 25
2.2. Reproduction 26
2.2.1. Colorimetric differentiation 27
2.2.2. Differentiation by polarization 28
2.2.3. Active glasses 30
2.2.4. Auto-stereoscopic screens 31
2.2.5. Virtual reality headsets 33
2.3. Motion parallax restitution 34
2.3.1. Pseudoscopic movement 34
2.3.2. Correcting pseudoscopic movements 35
2.3.3. Monoscopic motion parallax 40
Chapter 3. Causes of Visual Fatigue in Stereoscopic Vision 41
3.1. Conflict between accommodation and convergence 41
3.2. Too much depth 44
3.3. High spatial frequencies 46
3.3.1. Limits of fusion 49
3.3.2. Comfort and high frequencies. 50
3.4. High temporal frequency 52
3.5. Conflicts with monoscopic cues 52
3.6. Vertical disparities 53
3.7. Improper device settings 55
3.7.1. Quality of image and display 55
3.7.2. Differences between left and right images 56
3.7.3. Speed of correction of pseudoscopic movements 57
Chapter 4. Short- and Long-term Consequences 59
4.1. Short-term effects 59
4.1.1. Decreasing ease of accommodation 59
4.1.2. Decrease in stereoscopic acuity 59
4.1.3. Effects on the punctum proximum 61
4.1.4. More subjective effects 61
4.2. Long-term consequences 62
4.2.1. Long-term effects on children 62
Chapter 5. Measuring Visual Fatigue 63
5.1. Visual acuity 63
5.1.1. Different possible measurements 64
5.1.2. Optotypes 64
5.2. Proximum accommodation function 65
5.3. Ease of accommodation 66
5.4. Stereoscopic acuity 67
5.4.1. Tests of distance vision 67
5.4.2. Tests of near vision 68
5.5. Disassociated heterophorias 71
5.6. Fusional reserves 72
5.7. Subjective tests 74
Chapter 6. Reducing Spatial Frequencies 75
6.1. Principle 75
6.2. Technical solution 75
6.2.1. Wavelets 76
6.2.2. BOX FILTER 92
6.2.3. Using a rolling average and other "blurs" 98
6.2.4. Comparison of algorithms 103
6.2.5. Chosen solution 114
6.3. Experiment 116
6.3.1. The task 116
6.4. Measurements of fatigue taken 118
6.4.1. Objective measurements 118
6.4.2. Procedure 119
6.4.3. The subjects 120
6.5. Result 120
6.5.1. Proximum accommodation function 120
6.5.2. Ease of accommodation 121
6.5.3. Stereoscopic acuity 122
6.5.4. Effectiveness in execution of the task 122
6.5.5. Subjective measurements 123
6.5.6. Conclusions 124
6.5.7. Discussion 124
Chapter 7. Reducing the Distance Between the Virtual Cameras 131
7.1. Principle 131
7.1.1. Usefulness of stereoscopy in depth perception 132
7.1.2. The objects 133
7.1.3. Hypothesis 142
7.2. Experiment 142
7.2.1. Tasks 142
7.2.2. Experimental conditions 143
7.2.3. Subjects 144
7.2.4. Measurements 144
7.3. Results 145
7.3.1. Results for fatigue 145
7.3.2. Perception results 147
7.4. Discussion 152
7.4.1. Influence on visual fatigue 152
7.4.2. Influence on visual perception 153
Conclusion 155
Bibliography 157
Index 167
