Abstract
Immersive cinema relies on vision to orient and move the viewer through the portrayed scene. However some viewers are susceptible to cinema sickness, which has been linked to visually-induced percepts of self motion or vection. Recent advances have enabled cinematic frame rates much higher than the conventional 24 frames per second (fps). The resulting improved motion fidelity might promote vection with potentially positive (e.g., increased presence) or negative (e.g., cinema sickness) consequences. We measured the intensity of vection while observers watched stereoscopic 3-D computer graphics movies projected on a large screen. We fixed the refresh rate at 120 Hz (60 Hz per eye using shutter glasses), and manipulated the flash protocol to create 60 fps (single flash), 30 fps (double flash) and 15 fps (quadruple flash) for each eye. The stimuli simulated forward motion along a gently winding street at speeds of 20 and 40 km/h. The simulated camera exposure time was also varied (0, 8.33, 16.67 and 33.33 ms) to investigate effects of motion blur. Vection intensity was measured using a magnitude estimation technique for all conditions interleaved randomly. Results from eighteen observers showed that vection intensity was significantly higher at a simulated speed of 40 km/h than at 20 km/h, but there was no main effect of exposure time. For the no motion blur condition (0 s) at the slower speed, stronger vection was observed at higher frame rates as predicted. The lack of an effect of frame rate at the high speeds may have been due to a ceiling effect, as vection was much stronger in the fast conditions. The lack of influence of frame rate in the presence of motion blur is interesting and suggests that motion artefacts (such as judder) that are introduced at low frame rates could be hidden by motion blur.
Meeting abstract presented at VSS 2016