Tadashi Ichikawa

Acquisition of 3D image representation in multimedia ambiance communication using 3D laser scanner and digital camera

This paper addresses a new scheme of acquisition of 3D image representation from range data and texture data. The concept of a layered structure defined for painting, such as long- range, mid-range, and short-range views, that can be applied to a 3D image. Long and mid-range views are located at a reasonable distance, and therefore do not require the perfect 3D structure. Instead of describing the perfect 3D structure, an image can be represented more simply with range information through a plane-model approximation. Setting representation can be used like stage setting to approximate objects and describe a 3D structure by plane- model. It is effective as a simplified means of describing 3D image space as in long and mid-range views that does not require a detailed 3D structure. We can obtain the parameters of plane shape from the integration of range data measured by a 3D laser scanner and a number of still images captured by a digital camera.

Multimedia ambiance communication

The photo-realistic 3-D image space of multimedia ambiance communication offers enhanced interpersonal communication. Formed by taking the laws of perspective and the characteristics of human visual perception into account, the space provides a natural environment that users can feel to be a part of. It is based on the concept of a three-layer structure, with long-, mid-, and short-range views. We constructed a testbed for multimedia ambiance communication consisting of a high-speed graphics computer and a curved screen onto which images are stereoscopically projected from the rear, and developed a three-camera system for capturing environment images. In addition, we developed the two-plane expression for processing backdrop views and highly efficient mid-range views. Finally, we constructed a photo-realistic 3-D image space using these image processing techniques.

Structure analysis of natural scenes using census transform and region competition

In this paper we propse an approach to generate a panorama depth map which is dense enough to be used as a template for cutting out a texture image by the depth, i.e. structuring the scene into layers to construct a shared 3-D image space. For depth estimation, we make use of census transform for robust determination of correspondence of a stereo pair. To interpolate unknown disparities, we introduced a process influenced by the K-means algorithm. For densification of the depth data, we make use of Region Competition. During the stitching, the confidence of the data is improved for the overlapped areas by multiple evaluation of the disparity data.

High-quality stereo panorama generation using a three-camera system

A method for high quality stereo panorama mosaicing is presented. The surrounding scene is captured by our original 3-camera system as stereo moving picture sequences, and the images are stitched after improvement of the texture quality. The multi-purpose 3-camera system features accurate frame synchronization between 3 channels, and can be used outdoors through battery operation. For registration of panorama stitching, under the newly investigated distortion- free condition. Affine parameters are estimated through the overlapped areas by the steepest descent algorithm. The texture improvement has two steps, one is vertical resolution recovery by field integration, and the other is image enhancement by 2D quadratic Volterra filter which satisfies Weber-Fechners law. The presented method enables high quality stereo mosaicing with accurate mutual disparities between the channel and without visible distortion of textures.

Generation of a disparity panorama using a 3-camera capturing system

This paper presents a method to create a panorama disparity map of a natural environment from stereo images captured by our original multi-purpose 3-camera panorama capturing system which features accurate frame synchronization between 3 channels and can be used outdoors through battery operation. For robust determination of correspondences of a stereo pair, we make use of a census transform, a kind of non-parametric local transform. The census transform summarizes local image structure as a bit string, and gives very good stereo-matching results without such processes as image pyramids, bi-directional search, complicated matching evaluation, and too much edge detection dependent interpolation. To interpolate unknown disparities, we introduced a process influenced by the K-means algorithm. Then, use of 3-channel images and overlapping of the maps give multiple disparity values for one pixel, which enables screening of very confident values. We have obtained very good results on such complex scenes as contain branches and leaves of trees.

Multimedia ambience communication based on actual moving pictures in a steroscopic projection display environment

Multi-media Ambiance Project of TAO has been researching and developing an image space, that can be shared by people in different locations and can lend a real sense of presence. The image space is mainly based on photo-realistic texture, and some deformations which depend on human vision characteristics or pictorial expressions are being applied. We aim to accomplish shared-space communication by an immersive environment consisting of the image space stereoscopically projected on an arched screen. We refer to this scheme as ambiance communication. The first half of this paper presents global descriptions on basic concepts of the project, the display system and the 3-camera image capturing system. And the latter half focuses on two methods to create a photo-realistic image space using the captured images of a natural environment. One is the divided expression of the long-range view and ground, which not only gives more realistic setting of the ground but commands more natural view when synthesized with other objects and gives potentialities of deformations for some purposes. The other is the high quality panorama generation based on even-odd field integration and image enhancement by a two dimensional quadratic Volterra filter.

Multi-media ambiance communication based on actual moving pictures

Multi-media ambiance communication refers to a means of shared-space communication, that makes use of actual moving pictures captured by video camera, combined with the laws of perspective, as used in painting and the visual characteristics of human beings, to establish a photo-realistic quality three-dimensional image space that users can naturally feel part of. We aim to enable this ambiance communication by basing the shared-space on actual moving pictures rather than on an accurate three-dimensional image space, such as is used in computer graphics.

Wireless video communication system using PHS

In japan, with the start of the personal handy phone system service in 1995, there has been increased activity aimed at developing on mobile-multimedia communication services that take advantage of the systems high 32-kbps speed. Since wireless transmission paths suffer from fading errors, an important task in the implementation of mobile-multimedia communication services will be to guarantee high-efficiency communication despite the error-laden transmission channel. We present a study of a highly error-tolerant re- transmission-control method.

Three-dimensional image capturing and representation for multimedia ambiance communication

Multimedia Ambiance Communication is as a means of achieving shared-space communication in an immersive environment consisting of an arch-type stereoscopic projection display. Our goal is to enable shared-space communication by creating a photo-realistic three-dimensional (3D) image space that users can feel a part of. The concept of a layered structure defined for painting, such as long-range, mid-range, and short-range views, can be applied to a 3D image space. New techniques, such as two-plane expression, high quality panorama image generation and setting representation for image processing, 3D image representation and generation for photo- realistic 3D image space have been developed. Also, we propose a life-like avatar within the 3D image space. To obtain the characteristics of users body, a human subject is scanned using a CyberwareTM whole body scanner. The output from the scanner, a range image, is a good start for modeling the avatars geometric shape. A generic human surface model is fitted to the range image. The obtained model is topologically equivalent even if our method is applied to another subject. If a generic model with motion definitions is employed, and common motion rules can be applied to all models made from the generic model.