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This study investigates the influence of cross-modal interaction, particularly auditory stimuli, on perceived rendering quality thresholds in high-fidelity rendering. The experiment involved 48 volunteers and compared preferences between images rendered with and without related sound and noise. Results showed that unrelated sound and noise reduced the perceived rendering threshold, emphasizing the importance of audio in virtual reality scenarios.
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The Influence of Cross-modal Interaction on Perceived Rendering Quality Thresholds Vedad Hulusić, Matt Aranha, Alan Chalmers Warwick Digital Laboratory, University of Warwick, UK
Introduction • High-fidelity rendering COMPUTATIONALLY DEMANDING! • High-fidelity animation • …in real time?!?
Introduction • High-fidelity rendering COMPUTATIONALLY DEMANDING! • High-fidelity animation • …in real time?!? Rendering time:1h 48minutes Rendering resolution: 2048x1536 Frames rendered: 1440 No. of processors: 175-200
Human vision, perception and cross-modal interaction • Human Visual System • Angular sensitivity (internal spotlight) • Inattentional blindness • Cross-modal interaction • Importance of the sound in VR scenarios • Effect of audio on visual attention and perception “There is usually only one object in play at only one time … task involving more than a few objects can be handled by rapidly switching attention between the objects.”[1] [1] Rensink, R., 2000. Seeing, sensing and scrutinizing. Vision Research 40, 1469-1487.
Imperceptibly decreasing rendering quality • Selective rendering – point-of-gaze prediction • Saliency map • Tolerance (Aleph) map • Importance map • Rendering threshold • Altering the number of rays per pixel
Imperceptibly decreasing rendering quality • Selective rendering – point-of-gaze prediction • Saliency map • Tolerance (Aleph) map • Importance map • Rendering threshold • Altering the number of rays per pixel
Imperceptibly decreasing rendering quality • Employment of other senses – Auditory • Sound emitting objects (SEO) • Background music • Related and unrelated sound • High-quality audio
Imperceptibly decreasing rendering quality • Employment of other senses – Auditory • Sound emitting objects (SEO) • Background music • Related and unrelated sound • High-quality audio
Imperceptibly decreasing rendering quality • Our research: • Rendering thresholds • Altering the number of rays per pixel • Employment of other senses – Auditory • Related and unrelated sound
Experiment • 48 volunteers: 33 male, 15 female • Age 18-63 (avg. 25) • Each subject participated in only one (random) group • Three groups: no sound, related sound and noise • 28 pairs of images in random order per group • 2AFC (2-Alternative Force Choice) • Each sequence 16 seconds (3+5+3+5+?)
Visual stimuli • 4 scenes: 3 realistic environments + control scene • Rendered with modified Radiance “rpict”[*] • 1, 4, 9, 16, 25, 36 and 49 rays per pixel • Resolution 1024x768px [*] Developed by Debattista, K.
Audio stimuli • Scene related sound • Noise • White noise • Gray noise • Pink noise
Hardware and rendering time • Rendering hardware • Intel Core2Duo E6650 at 2.33GHz • 2GB DDR2 PC6400 RAM • Rendering times (seconds)
Visual difference predictor (VDP) • Comparison of each image with the gold standard image (49rpp) • HDR VDP[*] • Map of perceivable difference Mask image Target image Difference map [*] Mantiuk et al., Visible difference predictor for high dynamic range images, October 2004. IEEE
Results • Hypothesis: Each pair of images should have equal preference. • Pearson’s Chi-Square with Yates’ correction • Probability bound = 0.05 • Critical value = 3.841 • Degrees of freedom = 1
Results: Visual difference predictor • Assumes significant viewing time • Problems with random sampling method • Visually equivalent images[*] • Noticeable artefacts on the edges of the objects [*]Ramanarayanan et al., Visual equivalence: towards a new standard of image fidelity, SIGGRAPH 2007
Conclusion • Cross-modal interaction has significant affect on perceived threshold • Unrelated sound • noise reduces the perceived threshold • Related sound • heightened awareness of differences between rendering qualities
Future work • Greater granularity of rpp levels • Apply to animation • Higher quality of audio • 3D sound • Volume levels • BASIS OF CROSS-MODAL AWARE RENDERING FRAMEWORK
Thank you for your attention. Vedad Hulusić, University of Warwick V.Hulusic@warwick.ac.uk