<title>Temporal sampling requirements for stereoscopic displays</title>

Abstract

A series of three experiments examined temporal aliasing in stereoscopic displays. The first experiment compared aliasing in frontal plane motion of different disparities, while the second compared aliasing for motion in different depth directions. The results showed little effect of viewing conditions on perceived aliasing. The third experiment tested whether there was a binocular motion mechanism which integrated temporal sampling in the two eyes. The results were consistent with the first two studies in suggesting that aliasing is generated only by monocular motion signals. The data have both practical and theoretical implications: 1) motion produced by means of LCD glasses will require double the sampling rate needed for motion created by anaglyph methods and 2) the shortrange motion system is monocular. TEMPORAL ALIASINGDigital displays present spatially and temporally sampled versions of continuous images. Sampling, however, can create "aliasing" artifacts which result in unwanted image distortions and reduced fidelity. Because aliasing is such an important problem in image quality, there have been many studies examining the effects of spatial (e. g. , Nyman and Laurinen, 1982;Nyman and Laurinen, 1985) and temporal (e.g. , Watson et al. , 1986; Green 1992a) sampling in video displays. This is an important research topic because knowledge visual mechanisms which interpolate sampled signals may suggest new methods of image compression.The advent of stereoscopic displays presents a new opportunity to improve the realism -of video displays but also opens a new set of questions about sampling and aliasing. There has been some research on spatial sampling (e. g. , Tzelgov et al. , 1990) in stereoscopic displays but no studies on temporal sampling requirements.There are two possible ways that stereo displays might alter temporal sampling requirements. First, viewers usually verge on the plane of the image, so nonstereo displays present information to corresponding points on the two retinae. In stereo displays, however, the information may fall on noncorresponding points. This activates cortical disparity detectors in which are not involved in nonstereo viewing. There is clear psychophysical evidence that humans possess stereomotion detectors with very different properties from mechanisms for frontal plane motion (Regan, 1991).Moreover, there is other evidence (e. g., Tyler, 1971) that frontal plane and stereo motion mechanisms interact. Second, stereoscopic displays afford different ways to distribute the temporal sampling between the two eyes. In nonstereo displays, each eye receives images sampled at the same O-8194-0823-9/92/$4.OO SPIE Vol. 1669 Stereoscopic Displays andApplications III (1992) / 101 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/16/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx