Nobuyoshi Terashima

Virtual Space Teleconferencing : Real - time reproduction of 3D human images

Abstract Real-time reproduction of 3D human images is realized by an experimental system recently built as a prototype for virtual space teleconferencing, in which participants at different sites can feel as if they are colocated and can work cooperatively. At each sending and receiving site of the teleconferencing system, a 3D model of each participant is constructed from a wire frame model mapped by color texture and is rendered on a 3D display. In the current experimental system, real-time detection of facial features at the sending site is achieved by visually tracking tape marks pasted to the participants face. Movements of the head, body, hands, and fingers are detected in real time using magnetic sensors and data gloves. At the receiving site, the detected motion parameters are used to move nodes in the wire frame model to reproduce the movements of the participants at each sending site. Realistic facial expressions are reproduced through the use of simple motion rules applied to the tape mark tracking information. Through experimental evaluation, the optimal number of nodes for best quality has been obtained. Reproduction of facial expressions and synthesis of arm movements are examined. The reproduction speed using the optimal human model is approximately 6 frames/s. Examples of cooperative work by participants using the experimental system illustrate the effectiveness of virtual space teleconferencing.

Real-time reproduction of 3D human images in virtual space teleconferencing

Real-time reproduction of a 3D human image is realized by an experimental system built for the realization of virtual space teleconferencing, in which participants at different sites can feel as if they are at one site and can work cooperatively. In the teleconferencing system, a 3D model of a participant is constructed by a wire-frame model mapped by color texture and is displayed on 3D screen at the receiving site. In the experimental system, to realize real-time detection of facial features at the sending site, tape marks are attached to facial muscles, and the marks are tracked visually. To detect movements of the head, body, hands and fingers in real-time, magnetic sensors and data glove are used. When the movements of the participant are reproduced at the receiving site, the detected results are used to drive the nodes in the wire frame model. Using the experimental system, the optimum number of nodes for real-time reproduction is obtained. Results for real-time cooperative work using the experimental system are demonstrated.<<ETX>>

Mechanism of color breakup in field-sequential-color projectors

— To investigate color breakup in field-sequential-color projectors, we measured the threshold of color fusion frequency relative to retinal velocity of the moving edge on the color flicker field. The characteristic changed as the velocity approached saccade. The result suggests that the mechanism of color breakup differs according to the velocity of the image on the retina.

Parallax distribution for ease of viewing in stereoscopic HDTV

In order to identify the conditions which make stereoscopic images easier to view, we analyzed the psychological effects using a stereoscopic HDTV system, and examined the relationship between this analysis and the parallax distribution patterns. First, we evaluated the impression of 3-D pictures of the standard 3-D test chart and past 3-D video programs using some evaluation terms. Two factors were thus extracted, the first related to the sense of presence and the second related to ease of viewing. Secondly, we applied principal component analysis to the parallax distribution of the stereoscopic images used in the subjective evaluation tests, in order to extract the features of the parallax distribution, then we examined the relationship between the factors and the features of the parallax distribution. The results indicated that the features of the parallax distribution are strongly related to ease of viewing, and for ease of viewing 3-D images, the upper part of the screen should be located further away from the viewer with less parallax irregularity, and the entire image should be positioned at the back.

Mechanism of Color Breakup on Field‐Sequential Color Projectors

To investigate color breakup on field-sequential color projector, we measured threshold of color fusion frequency to retinal velocity of the moving edge on the color flicker filed. The characteristic changed in the velocity as saccade. The result suggests that the mechanism of color breakup differs by range of retinal velocity.

Experiment of virtual space distance education system using the objects of cultural heritage

Lecture exchanges are increasing year by year. To promote this distance education systems have been developed and put into practical use. As a step further, a virtual space distance education platform called HyperClass has been proposed. HyperClass is a class where a teacher and students who are at different locations, in reality their avatars, are brought together through the communication network, and they can have classes and do cooperative work as if they were attending the same classroom. Any multimedia materials for education can be introduced into HyperClass. HyperClass is based on HyperReality (HR). HR is the concept of combination of virtual reality and real reality. A prototype system for HyperClass has been developed and the 3D (three dimensional) objects of Japanese heritage were introduced into HyperClass. To evaluate the efficiency and effectiveness of HyperClass, an experiment has been carried out by interconnecting between Waseda University and Victoria University of Wellington through the Internet. Good results have been obtained.

Adaptive resolution image acquisition using image mosaicing technique from video sequence

We propose a layered image mosaicing method from a video sequence to acquire an adaptive resolution image. In research of art, for example, researchers often desires the full view of a painting and the details of certain regions, where fine brush-strokes are in it. The proposed method is to acquire the region of special interest at a fine resolution and the remaining image space at a coarser resolution by using a hand-held video camera which repeats moving, panning, tilting, zooming in and zooming out. To integrate video frames, image mosaicing methods can be used. However, existing mosaicing methods, in general, have a defect, where they perform inefficiently because wide angle image frames are registered after magnification. To solve this problem, the layered image mosaicing method is proposed. The proposed method can reduce processing time while it makes a mosaic image accurately. In this paper, the concept, algorithm and experiments are described. The experiments showed that the method was efficient and accurate for acquisition of an adaptive resolution image.

A method of automatic state acquisition for conflict detection of telecommunication service descriptions

Abstract The detection and elimination of telecommunication service interactions are still urgent problems. Conflict, which is discussed in this paper, is one of the problems that comes under heading of telecommunication service interactions. The main problem in detecting conflict is due to the difficulty of grasping and predicting states when services are combined. This paper describes a method of automatically acquiring these states. Telecommunication service behaviors are assumed to be described as a set of rules. When acquiring the states by applying rules, it is necessary to know whether an arbitrary terminal state is synchronized with the other terminal states. Although determining synchronization among multiple terminal states is ordinarily difficult for the designer, by using the proposed method, states can be automatically generated without the designers intervention.

Construction of realistic three dimensional facial images using video images

A method for constructing 3D human facial images which maintains the characteristics of video input image is proposed. First, a personalized 3D polygonal facial model is constructed from two orthogonal facial images. Video input frames are modified, and the movements of facial feature points are tracked and measured based on the contraction rule of facial muscles. The vertices of the 3D polygons are altered accordingly, and the modified input frame is texture mapped directly onto to the forementioned model. This method was implemented using an ordinary CCD camera and computer, and an experiment using one persons data showed that realistic facial images is reconstructed with high speed and precision.

Construction of facial expressions using a muscle-based feature model

An efficient method for constructing facial images for use in telecommunication applications is proposed. This method uses a simple 3D feature model, which consists of polygons, which describe the shape of the face, and elastic linear springs, which simulate the natural movements of facial muscles. This method requires only two orthogonal facial images, and could easily be implemented on a relatively low-spec PC. Experimental results showed good results that various facial expressions could be synthesized and displayed from arbitrary directions.