Kunio Yamada

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.

Motion Segmentation with Census Transform

This paper presents a new approach to motion segmentation. Unlike most other methods, the proposed approach relies on summarized local image structure obtained by census transform, and not on absolute luminance values. We apply census transform for two frames from the sequence which are registered to the sub-pixel accuracy regarding to the moving target object. The registration is carried out by estimation of affine parameters. The two sets of resulting local image structures, in the forms of bit strings, give good and dense correspondence on the object to segment the region. We study the effectiveness of the sub-pixel registration compared to the pixel unit registration. We show segmentation results for natural scenes.

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.

Virtual view generation of natural panorama scenes by setting representation

This paper proposes a technique to generate virtual views of a natural panorama scene. The scene is captured by an original 3-camera system. The images are stitched into a stereo panorama and the depth is estimated. The texture panorama is segmented into regions, each of which can be regarded to be approximated as a plane. The planar parameter set of the region for setting representation is calculated depending on the depth data. According to the representation the virtual views are generated using center panorama texture, and left and right panoramas are used for occlusion compensation.

Laser Fabrication of Nanomaterials in Solution

We developed new methods to form small nanomaterials in a solution, which include a liquid-phase laser ablation and laser-induced structural change of the nanomaterials. Here, we report our recent advances of the methods on gold as the typical example, and on manganese as an application.

Integral 3D imaging system using monocular 2D video and depth data

An autostereoscopic imaging system, which displays moving actual images created from 2D video and depth data, is proposed. The system consists of a depth camera, signal processing algorithms, and an integral display prototype. The specifications are as follows: (a) Depth camera: a monocular VGA video camera with optical distance sensor captures 2D texture image and its depth map simultaneously. (b) Signal processing: 10x10 parallax images are created from the video stream, and the angle between two neighboring parallax images is 0.8 degrees. (c) Display: The display device is contact type (LCD) or projection type (LCOS), and the optical device is a microlens-array. 2D resolution of the 3D image is 720 cycle/radian at a viewing distance, and a viewing zone is about 8 degrees. Noticeable defects due to occlusions are not found within the viewing zone. The method of transmission of texture and depth data has higher compatibility with conventional coding technologies than transmission using compressed parallax images. And the transmission method enables the users to choose various types of displays and the way of displaying the contents. Therefore we believe that this system is a candidate for the future 3D television system.

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.