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The University of Tokyo 0.305 0.988 0.675 0.740 0.013 0.524 0.535 0.738 0.000 0.309 0.687 1.000 + = 0.816 0.571 0.582 0.000 0.241 0.845 1.000 0.361 0.574 0.962 0.557 0.598 Figure 1: Locating optimal viewpoints by individually estimating the visibility quality of each feature subvolume. The value under each image represents its corresponding estimate normalized to [0.0, 1.0]. ABSTRACTOptimal viewpoint selection is an important task because it considerably influences the amount of information contained in the 2D projected images of 3D objects, and thus dominates their first impressions from a psychological point of view. Although several methods have been proposed that calculate the optimal positions of viewpoints especially for 3D surface meshes, none has been done for solid objects such as volumes. This paper presents a new method of locating such optimal viewpoints when visualizing volumes using direct volume rendering. The major idea behind our method is to decompose an entire volume into a set of feature components, and then find a globally optimal viewpoint by finding a compromise between locally optimal viewpoints for the components. As the feature components, the method employs interval volumes and their combinations that characterize the topological transitions of isosurfaces according to the scalar field. Furthermore, opacity transfer functions are also utilized to assign different weights to the decomposed components so that users can emphasize features of specific interest in the volumes. Several examples of volume datasets together with their optimal positions of viewpoints are exhibited in order to demonstrate that the method can effectively guide naive users to find optimal projections of volumes.

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This paper describes initial results of a 3D field topology analysis for automating transfer function design aiming at comprehensible volume rendering. The conventional Reeb graph-based approach to describing topological features of 3D surfaces is extended to capture the topological skeleton of a volumetric field. Based on the analysis result, which is represented in the form of a hyper Reeb graph, a procedure is proposed for designing appropriate color/opacity transfer functions. Two analytic volume datasets are used to preliminarily prove the feasibility of the present design methodology.

This paper takes advantage of a 3D eld topology analysis for automating visualization design aiming at volume data mining. The conventional Reeb graph-based approach to describe the topological features of 3D surfaces is extended to capture the topological skeleton of a v olumetric eld. Based on the analysis results, which are represented in the form of hyper Reeb graph, we propose two methods for eective geometric object tting and two principles to design appropriate color/opacity transfer functions for direct volume rendering. Feasibility study of the present methodology is performed with a large scale 4D simulated dataset from atomic collision research.

The effect of audiovisual interactions on size perception has yet to be examined, despite its fundamental importance in daily life. Previous studies have reported that object length can be estimated solely on the basis of the sounds produced when an object is dropped. Moreover, it has been shown that people typically and easily perceive the correspondence between object sizes and sound intensities. It is therefore possible that auditory stimuli may act as cues for object size, thereby altering the visual perception of size. Thus, in the present study we examined the effects of auditory stimuli on the visual perception of size. Specifically, we investigated the effects of the sound intensity of auditory stimuli, the temporal window of audiovisual interactions, and the effects of the retinal eccentricity of visual stimuli. The results indicated that high-intensity auditory stimuli increased visually perceived object size, and that this effect was especially strong in the peripheral visual field. Additional consideration indicated that this effect on the visual perception of size is induced when the cue reliability is relatively higher for the auditory than for the visual stimuli. In addition, we further suggest that the cue reliabilities of visual and auditory stimuli relate to retinal eccentricity and sound intensity, respectively.

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