1. On Seeing Transparent Surfaces in Stereoscopic Displays Inna Tsirlin-Zaharescu, Robert S. Allison and Laurie M. Wilcox

2. Motivation Stereo-transparency presents a difficult problem both theoretically and computationally Small number of psychophysical studies addressed stereo-transparency (Akerstrom & Todd 1988, Gepshtein & Cooperman 1998, Wallace & Mamassian 2004) Goals –Investigate the number of overlaid planes limiting the perception of stereo- transparency –Study the combined effects of density, disparity and number of planes on the percept of stereo- transparency.

3. Stimuli were 12.6 o square RDS’s depicting n overlaid planes of dots with inter-plane depth separation d. In Glass planes dots were arranged in a horizontal-shift Glass pattern. Task: the observers were asked to report the number of planes and the number of Glass planes they perceived. Stimulus parameters: Density: 2, 6.3, 10, 15.7 dots/deg 2 Inter-plane separation: 1.9’, 3.8’, 5.7’, 7.6’ Number of planes: 2, 3, 4, 5, 6 Methods

4. DEMO

5. 1.9 3.8 5.7 7.6 2 PLANES3 PLANES 5 PLANES 4 PLANES 6 PLANES PERCENT CORRECT INTER-PLANE DISPARITY (min. of arc) 100 50 0 100 50 0 100 50 0 100 50 0 100 50 0 1.9 3.8 5.7 7.6 6.3 dots/deg 2 10 dots/deg 2 15.7 dots/deg 2 2 dots/deg 2 DENSITY PERCENT CORRECT INTER-PLANE DISPARITY (min. of arc) 1.9 3.8 5.7 7.6 100 50 0 5 PLANES 6.3 dots/deg 2 10 dots/deg 2 15.7 dots/deg 2 2 dots/deg 2 DENSITY

6. Possible explanation Detrimental effects on stereo-transparency Increase in the number of planes Increase in density Size-disparity correlation Adapted from McKee & Verghese 2002 Increase in disparity beyond an optimal value Disparity poolingSmall disparities Discussion

7. Akerstrom and Todd (1988) Wallace and Mamassian (2004) Effect of increase in disparity Performance decreased No effect Stimuli parameters 28.7 dots per square degree 7.08’ dot size 112’ max. disparity 8.9 dots per square degree 4.5’ dot size 60’ max. disparity Density-disparity interaction

8. We are able to segregate up to 3 planes under all conditions and up to 5 planes under optimal conditions. Increasing the number of planes, density and disparity beyond an optimal value degrades performance The interaction of these parameters plays an important role in stereo-transparency and cannot be ignored in future research Conclusions Stereoscopic modeling based on a combination of position- shift and phase-shift energy detectors cannot account for the experimental results.

9. Thank you! Questions?

10. Motivation Stereo-transparency presents a difficult problem both theoretically and computationally Left image Right image Uniqueness constraint Continuity constraint Small number of psychophysical studies addressed stereo-transparency –Used RDS stimuli with only 2 overlaid planes –Varied RDS parameters in isolation

11. Types of stereo-transparency True TransparencyPseudo- transparency