some issues on the relation between visual localization and eye movements were discussed. Visual mislocalization contingent upon saccadic eye movements has been sometimes explained as showing inaccuracy of an eye position signal originated from the central oculomotor system. Recent psychophysical studies suggested that the time course of extraretinal eye position signals is not consistent with that of actual eye position and that the visual stability which we experience in the everyday life is not explained in terms of extraretinal eye position signals. Some other possible explanations were presented. It was also shown that the extraretinal eye position signal for pursuit eye movements is inaccurate and not sufficient for informing us of the distance the eye tracked. Finally, the role of vergence eye movements in depth perception was discussed. It was stressed that a small fluctuation of vergence results in a large change of the fixated position and that vergence cannot be a strong cue for depth perception.
This paper introduces three types of medical systems applied 3-D technologies. We first propose a 3-D system for images taken by a binocular microscope. The proposed system displays images on 3-D monitor and allows many people view it at the same time to obtain depth information for the precise operation. The second discussion is about images by an endoscope. The developed system converts from originally 2-D image into a 3-D image by 2D/3D real-time conversion technique. We also discuss on MRA images such as blood vessels. Our 3-D system gives clearly complicated positioning between vessels. We believe 3-D medical imaging could open up new stage in medical fields.
In this age of advanced and complicated clinical dentistry, knowledge acquisition through books and training methods using mannikins cannot provide adequate training results. With Virtual Reality (VR) system, our approach is to develop a "therapeutic simulator" whereby the skill of remedy of expert dentists can be inherited intuitively by dental trainees. The digitizer has 7 links with 7 degrees of freedom like the human arm, and an electric rotary encoder was set to evaluate the movement of the handpiece with accuracy better than 0.5mm. The application of virtual reality provides the advantages of 1) supplementing intermediate and mannikin-based training in the process of practical education, 2) enables training in abnormal cases as when the patient's tongue moves suddenly, and 3) enables three-dimensional recording of the process of tooth cutting, which can be played back later for review. This study was supported by the Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture in Japan (No. (A) (1) 05507004).