At present, a general belief is that viewing and 3-D images causes eye fatigue and discomfort because of the inconsistency between accommodation and convergence. However, our previous research found that both accommodation and convergence follow the position of virtual 3D objects synchronously. This was especially true in the case of young subjects aged in their 20s.In this study, we simultaneously measured variation of accommodation and convergence and their dependence on pupil diameter by changing the intensity of illumination as well as the brightness of the viewing screen.As a result, in the strongly lit environment, both accommodation and convergence nearly focused on the position of vertical objects. In a weakly lit environment, accommodation tends to focus on a position slightly father than that of convergence which is explained by the variation of pupil diameter.

Recently we developed a device by combining a binocular autorefractometer and an eye mark recorder. Then, using the device together with images of very natural and high quality, we have carried out a sequence of experiments on simultaneous measurements of both accommodation and convergence while viewing virtual 3D objects.The results show that there is essentially no discrepancy in the dynamical behaviors of accommodation and convergence especially for young subjects and that they are hence very close to the case of natural viewing of real 3D objects.Following our previous experiments, we now investigate effects of longtime viewing of virtual 3D objects on the eye function of accommodation and convergence. We show that the synchronous dynamical behaviors of accommodation and convergence are definitely not a temporal effect but last for a long time.

Three-dimensional display technology has developed rapidly in recent years. This has been accompanied by increasing problems of visual complaints such as eye strain. There are also various types of digital signage, in which text information moves on a screen. In this paper, we conducted two experiments for the purpose of easy to read, dynamic characters that pop out when viewing 3D images, and safe and comfortable 3D viewing. We conducted a survey of accommodation and convergence of viewers when they watched a movie with a television opaque projector for large outward projection of characters. We also compared the results of a survey on the readability of characters that pop out and the proportion and the perception of the amount of protrusion. We examined the maximum distance in which subjects' eyes could recognize the 3D character representations without any difficulty or discomfort. The distance of the images as they popped out from the screen as a theoretical virtual target was compared with what the subjects recognized according to each age group. There was no significant difference between the theoretical and observed values in any age groups. In a second experiment, we performed objective measurements of accommodation and convergence for 3D character representation using original instruments. We then compared the values of the measurements of the subjects with the theoretical positions of emergence. When a subject recognized a 3D character representation, the position of his or her accommodative and convergent focus was closer to the theoretical position of the virtual object that projected out from the screen. Nearly all of the subjects recognized the 3D representation at even 3.8 degrees, which was the largest parallax condition. Cognitively, almost all of the subjects viewed the positions of the objects correctly without much difficulty.

No abstract

No abstract