Constructing Virtual Cities by Using Panoramic Images

Simultaneously acquired omni-directional images contain rays of 360 degree viewing directions. To take advantage of this unique characteristic, we have been developing several methods for constructing virtual cities. In this paper, we first describe a system to generate the appearance of a virtual city; the system, which is based on image-based rendering (IBR) techniques, utilizes the characteristics of omni-directional images to reduce the number of samplings required to construct such IBR images. We then describe a method to add geometric information to the IBR images; this method is based on the analysis of a sequence of omni-directional images. Then, we describe a method to seamlessly superimpose a new building model onto a previously created virtual city image; the method enables us to estimate illumination distributions by using an omni-directional camera. Finally, to demonstrate the methods' effectiveness, we describe how we implemented and applied them to urban scenes.     

Separating reflection components of textured surfaces using a single image

In inhomogeneous objects, highlights are linear combinations of diffuse and specular reflection components. To our knowledge, all methods that use a single input image require explicit color segmentation to deal with multicolored surfaces. Unfortunately, for complex textured images, current color segmentation algorithms are still problematic to segment correctly. Consequently, a method without explicit color segmentation becomes indispensable and This work presents such a method. The method is based solely on colors, particularly chromaticity, without requiring any geometrical information. One of the basic ideas is to iteratively compare the intensity logarithmic differentiation of an input image and its specular-free image. A specular-free image is an image that has exactly the same geometrical profile as the diffuse component of the input image and that can be generated by shifting each pixel's intensity and maximum chromaticity nonlinearly. Unlike existing methods using a single image, all processes in the proposed method are done locally, involving a maximum of only two neighboring pixels. This local operation is useful for handling textured objects with complex multicolored scenes. Evaluations by comparison with the results of polarizing filters demonstrate the effectiveness of the proposed method.     

Estimation of F-Matrix and image rectification by double quaternion

Fundamental Matrix, or F-Matrix, is one of the most important and elemental tools in the field of computer vision. In conventional methods for estimating the F-Matrix, an eight-point algorithm is adopted. First, an approximate F-Matrix is calculated by a linear solver using at least eight corresponding pairs. Since this linear optimization method excludes an essential property, the rank 2 constraint, a method based on a singular value decomposition (SVD) is applied to impose the constraint. This last step with SVD, however, provides additional noise in the F-Matrix. Several methods introduce parameterizations taking into account the rank 2 constraint and optimized nonlinearly without SVD. In this paper, we propose a novel parameterization for the nonlinear optimization which includes this constraint. We adopt double quaternion (DQ) and a scalar as the parameter set. Experimental results show that the nonlinear optimization with our parameterization is competitive with other parameterization methods. Moreover, through the proposed parameterization, we can obtain two transformations for the two input images. These transformations lead to a novel method to estimate epipolar lines and to rectify the image pairs. This rectification method can deal with any image pairs in the same manner whether the epipoles are inside or outside the images.     

A note on deterministic three-way tape-bounded two-dimensional Turing machines

In this paper, we first investigate the relationship between the accepting powers of four-way two-dimensional finite automata and deterministic three-way tape-bounded two-dimensional Turing machines whose input tapes are restricted to square ones. The second part of this paper solves several open problems concerning closure properties of deterministic three-way tape-bounded two-dimensional Turing machines.     

The Great Buddha Project: Digitally Archiving,Restoring, and Analyzing Cultural Heritage Objects

This paper presents an overview of our research project on digital preservation of cultural heritage objects and digital restoration of the original appearance of these objects. As an example of these objects, this project focuses on the preservation and restoration of the Great Buddhas. These are relatively large objects existing outdoors and providing various technical challenges. Geometric models of the great Buddhas are digitally achieved through a pipeline, consisting of acquiring data, aligning multiple range images, and merging these images. We have developed two alignment algorithms: a rapid simultaneous algorithm, based on graphics hardware, for quick data checking on site, and a parallel alignment algorithm, based on a PC cluster, for precise adjustment at the university. We have also designed a parallel voxel-based merging algorithm for connecting all aligned range images. On the geometric models created, we aligned texture images acquired from color cameras. We also developed two texture mapping methods. In an attempt to restore the original appearance of historical objects, we have synthesized several buildings and statues using scanned data and a literature survey with advice from experts.     

Effect of lubrication on impact drive mechanism

The impact drive mechanism (IDM) device moves utilizing impulsive force caused by rapid deformations of piezoelectric elements and friction. Most of the devices utilizing impulsive force and frictional force are used on only a dry base. In this paper, the movement performance of the IDM on fluid lubricated surfaces is investigated. The movement on fluid lubricated surfaces and that in oil are as minute as that on a dry base. In experiments, the movement of the device of the IDM on a fluid lubricated surface is the same as the calculated movement by assuming a dry surface. The standard deviation of movement on a fluid lubricated surface is smaller than that on a dry surface. Considering the small distribution of the movement and the antirust of the devices, the devices utilizing impulsive force should be driven under the boundary lubrication.     

Two-dimensional automata with rotated inputs

This paper introduces a new type of automata on a two-dimensional tape, which decides acceptance or rejection of an input tape x by scanning the tape x from various sides by various automata. The accepting power of such an automaton is investigated. This paper mainly concentrates on investigating the accepting power of two-dimensional automata which consist of four parallel/sequential array automata, say M₁, M₂, M₃, and M₄, and which accept an input tape x if and only if x, x^R, (x^R)^R, and ((x^R)^R)^R are accepted by M₁, M₂, M₃, and M₄, respectively, where for any tape y, y^R is the tape obtained by rotating y clockwise 90°.     

Nonclosure property of nondeterministic two-dimensional finite automata under cyclic closure

It was unknown whether or not the class of sets of square tapes accepted by nondeterministic two-dimensional finite automata is closed under cyclic closure. This short paper solves this problem, and shows that the class is not closed under row or column cyclic closure.     

Deuterium retention in SiC coated graphite by D2+ implantation

The doped graphite tiles bolted to the active cooling heat sink, made of GBST1308 (1% B₄C, 2.5% Si, 7.5% Ti) coated with SiC, are now being used as the only plasma facing material (PFM) for the EAST device since the campaign of 2008. From the plasma density and fueling point of view, it is important to study thoroughly the hydrogen isotope retention in this kind of SiC-coated doped graphite. D₂⁺ implantations into the SiC coated doped graphite were performed at Shizuoka University. The chemical states of Si and C were studied by means of X-ray photoelectron spectroscopy (XPS), and the thermal desorption behavior of deuterium was analyzed by thermal desorption spectroscopy (TDS). It was found that deuterium was trapped by both C and Si in the SiC coatings. In the previous studies, Oya et al. reported the deuterium retention behavior in polycrystalline β-SiC. In this paper, difference of retention behavior in β-SiC and SiC coating will be also discussed.