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Stereoscopic Viewing. Summarized by Geb Thomas. Learning Objectives. Learn how to calculate retinal disparity Understand the variety of cues that provide depth perception Understand the main stereo viewing devices and the differences between them
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Stereoscopic Viewing Summarized by Geb Thomas
Learning Objectives • Learn how to calculate retinal disparity • Understand the variety of cues that provide depth perception • Understand the main stereo viewing devices and the differences between them • Understand how to calculate important engineering parameters of stereoscopic display systems
Computation of Retinal Disparity • Cormack and Fox • Images of objects nearer or farther than fixation fall on noncorresponding points on the retinas -- retinal disparity • Typically Assume that all points are on the horizontal fixation plane
Fixation Angle 1 = ATN[J+Af/Df] Angle 2 = ATN[J-Af/Df] Convergence = Ang1 + Ang2
Target Angle 3 = ATN[J+At/Dt] Angle 4 = ATN[J-At/Dt] ct = Ang3 + Ang4 r = angle cf - angle ct
Stereoscopic Displays • “3D visual display systems for virtual environments,” McKenna and Zeltzer • Display Characteristics • 5 Display Designs
Visual Cues and Display Attributes • Field of View -- angle subtended by viewing surface (human eye 120x180) • Spatial Resolution -- pixels (1280x1024 for many monitors; human has fovial region for 1-2 deg, sensitivity of 2-4 cycles/degree ~ 30 arc-sec) • Refresh and Update rates -- critical fusion frequency ~60Hz, 10-15Hz update rate for motion.
Visual Cues and Display Attributes, Cont. • Brightness -- from 1-1000 mL, response follows Weber’s law at ~2% contrast. Most displays range from 2-8 to 20-60mL. • Color -- Trichromatic color reproduction is somewhat noisy process, limits range of color reproduction. • Information Rate and Bandwidth -- Human eye info rate -- 4.3Mbits/sec along nerve pathways, monitor has 2 Gbits/sec.
Visual Cues and Display Attributes, Cont • Viewing Zone/ Volume Extent • Number of Views
Depth Perception and Depth Cues • Stereoscopic vrs. Autostereoscopic • Oculomotor cues -- vergence and accomodation • Binocular disparity • Binocular depth resolution • Motion parallax • Pictorial Depth Cues -- Overlap, image size, linear perspective (position), texture gradient, aerial perspective, shading
Learning Objectives • Learn how to calculate retinal disparity • Understand the variety of cues that provide depth perception • Understand the main stereo viewing devices and the differences between them • Understand how to calculate important engineering parameters of stereoscopic display systems