論文 - 松山　克胤

Co-Ordinate: Reconstruction of Three Dimensional Geometric Diagrams from a Single Image

Katsutsugu Matsuyama, Kouichi Konno

The Journal of the Society for Art and Science   13 ( 2 ) 85 - 96   2014年06月  [査読有り]

学会誌  共著・分担

We designed a new algorithm for reconstructing three-dimensional (3D) geometric diagrams. By extracting the orthogonality of the coordinate axes, the contents of labels, the positional relationships between labels and other elements, and direct and indirect connection relationships between elements, we define a score function and derive the optimal parameters that minimize it. This allows the elements to be reconstructed in 3D space and allows the system to create diagrams with different viewpoints. In our system, the reconstructed elements are redrawn with explicit orthogonal coordinate axes. The user can directly move the axes as an interface for changing viewpoints. The system allows the user to edit and attach elements to the diagram interactively.

Pairwise matching of 3D fragments using fast fourier transform

Enkhbayar Altantsetseg, Katsutsugu Matsuyama, Kouichi Konno

The Visual Computer   30 ( 6-8 ) 929 - 938   2014年05月  [査読有り]

学術誌  共著・分担

In this paper, we introduce a new method for pairwise matching of broken fragments from unorganized point clouds. We use a new descriptor that contains not only the cluster of feature points but also curves along the principal directions of the cluster. In our method, feature points are extracted by using the curvature values of points. Curves of the descriptor are approximated using Fourier series. The main idea is motivated by comparing descriptor curves between each cluster of matching faces. For comparing curves, the Fourier coefficients of each curve are computed by using Fast Fourier Transform and total energies of curves are compared.

An Estimation of Earthenware's Surface Shape Using Quadric Surfaces

Tsutomu Kinoshita, Katsutsugu Matsuyama, Kouichi Konno

The Journal of the Society for Art and Science   13 ( 1 ) 21 - 33   2014年03月  [査読有り]

学会誌  共著・分担

In most cases, earthenware is broken when it is excavated from ruins. This situation requires restoration for assembling the earthenware's pieces. The point clouds measured by a three-dimensional device are useful to restore the earthenware. Some methods to find adjacent pieces of earthenware using a computer have been proposed. These methods aim to restore broken earthenware by connecting adjacent pieces with using digital data. If, however, earthenware with large missing portions is restored, it is impossible to estimate the adjacent piece using local adjacency. Due to this, it is necessary to estimate the whole shape of earthenware. It is also possible to continue sequential local estimation for estimating whole shape of earthenware, but the distortion occurs in many cases. In this paper, we propose a method to estimate the whole shape of earthenware with quadric surfaces. Since most earthenware is produced to be as close as rotational shapes, quadric surfaces are suitable to represent rotational shapes. In our method, the uneven pattern on the surface is removed in the first step according to the Taubin's smoothing method. Next, the point cloud from which uneven patterns are removed is divided into several groups. After that, each point cloud is fitted to quadric surfaces represented by the algebraic equation. Finally, the sequences of points generated from quadric surfaces are interpolated and the free-form surfaces corresponding to the surface of the earthenware are generated.

Reconstruction method of trimmed surfaces with maintaining G1-continuity with adjacent surfaces

Yuta Muraki, Katsutsugu Matsuyama, Kouichi Konno, Yoshimasa Tokuyama

Computer Aided Design and Applications   11 ( 2 ) 165 - 171   2013年10月  [査読有り]

学術誌  共著・分担

In 3D CAD systems, reconstruction of trimmed surfaces is one of the important research topics. When 3D CAD data is exchanged between different CAD systems, it does not deliver the specifications of CAD systems completely. Therefore, we have to correct the CAD data, such as moving the point in order to fill gaps. Generally, CAD data is expressed by set of trimmed surfaces. Then, we need to modify the trimmed surfaces. It is necessary, however, to modify the trimmed surface shape so as to maintain geometrical consistency of the boundary edges and surfaces in direct modeling, and this is a big restriction. It is effective to apply a new free-form surface to a closed region enclosed with the modified edges because the consistency of a trimmed surface can be maintained. Many shapes with holes or concave shapes are included in CAD data. Moreover, it is necessary to consider maintaining G1-continuity with adjacent surfaces, but it is difficult to reconstruct the trimmed surface by the conventional surface fitting method. In this paper, we propose the reconstruction method of trimmed surfaces with maintaining G1-continuity with adjacent surfaces. In the proposed method, boundary edges are input and surfaces are output. Two surfaces are connected with G1-continuity by using the control points at the connection section obtained from cross boundary derivatives. In addition, the control points in the region or on the discontinuous boundaries are obtained by approximating sample points, and the proposed method can also be applied to shapes with holes or concave shapes.

High-quality Approximation Technique for Two G1-continuous Offset Surfaces

Naoyuki Satoh, Katsutsugu Matsuyama, Kouichi Konno, Yoshimasa Tokuyama

Computer Aided Design and Applications   11 ( 1 ) 78 - 89   2013年09月  [査読有り]

学術誌  共著・分担

This paper proposes a technique for approximating two G1-continuous offset surfaces. Since offset surfaces are in general not rational representation, spline approximations of offset surfaces are widely used. However, when two G1-continuous offset surfaces are approximated using existing methods, the shape data quality is reduced because gaps or creases arise between two approximated surfaces. Our technique generates two G1-continuous approximated surfaces represented by C1-continuous bicubic B-spline surfaces. The approximated surfaces are higher quality than those generated using existing methods, because no gaps or creases arise between those surfaces.

Data Compression Method for Trimmed Surfaces Based on Surface Fitting with Maintaining G1 Continuity with Adjacent Surfaces

Yuta Muraki, Katsutsugu Matsuyama, Kouichi Konno, Yoshimasa Tokuyama

Computer-Aided Design and Applications   9 ( 6 ) 811 - 824   2013年08月  [査読有り]

学術誌  共著・分担

We propose a data compression method based on surface fitting method. Our method enables efficient surface data compression by using the surface fitting method. With the approximation method that uses boundary curves and sample points based on a tangent plane at the boundary edges, the surface fitting method can also be applied to shapes with holes or concave shapes. Moreover, in order to maintain G1 continuity with adjacent surfaces, the cross boundary derivatives obtained by the surface interpolation method are applied to the connection section with adjacent surfaces. When a surface is generated in good accuracy, the original surface element can be deleted and data size can be drastically reduced.

分散軽量化手法の計算負荷を考慮した大規模ポリゴンモデルの領域分割手法

塩谷大樹，松山克胤，今野晃市，徳山喜政

芸術科学会論文誌   12 ( 2 ) 82 - 91   2013年06月  [査読有り]

学会誌  共著・分担

筆者らは、ＱＥＭ手法を高速に実行することができる、分散ＱＥＭ手法を提案している。分散ＱＥＭ手法は、データを分散させて、複数のＰＣで並列にＱＥＭ手法を適用することにより高速化を実現したものである。本研究は、既提案の分散ＱＥＭ手法の拡張を行うも のであり、新たな領域分割手法の開発により、分散化効率の向上および適用可能なデータサイズの向上を行うものである。既提案手法では単純にサーバあたりのポリゴン数が均等になるように領域分割が行われているのに対し、本手法では、ポリゴンモデルの局所的な特徴が領域ごとに異なる事実に着目し、効率的な分散化のための領域分割を行う。また、既提案手法ではクライアントＰＣで領域分割を行っていたのに対し、各サーバで分散的に データ読み込みを行うことで、より大規模なデータに対しても分散ＱＥＭ手法を適用可能にする。分散軽量化の処理時間は、領域分割処理と軽量化処理にかかる時間の合算である。本手法は従来の手法に比べて、領域分割処理にかかる時間は増大したが、軽量化処理にかかる時間については大幅な改善が行われ、結果として計算時間の短縮を行うことができた。

Feature Line Extraction from Unorganized Noisy Point Clouds Using Truncated Fourier Series

Enkhbayar Altantsetseg, Yuta Muraki, Katsutsugu Matsuyama, Kouichi Konno

The Visual Computer   29 ( 6-8 ) 617 - 626   2013年04月  [査読有り]

学術誌  共著・分担

The detection of feature lines is important for representing and understanding geometric features of 3D models. In this paper, we introduce a new and robust method for extracting feature lines from unorganized point clouds. We use a one-dimensional truncated Fourier series for detecting feature points. Each point and its neighbors are approximated along the principal directions by using the truncated Fourier series, and the curvature of the point is computed from the approximated curves. The Fourier coefficients are computed by Fast Fourier Transform (FFT). We apply low-pass filtering to remove noise and to compute the curvature of the point robustly. For extracting feature points from the detected potential feature points, the potential feature points are thinned using a curvature weighted Laplacian-like smoothing method. The feature lines are constructed through growing extracted points and then projected onto the original point cloud. The efficiency and robustness of our approach is illustrated by several experimental results.

Feature Extraction and Modification for Illustrating 3D Stone Tools from Unorganized Point Clouds

Enkhbayar Altantsetseg, Yuta Muraki, Katsutsugu Matsuyama, Fumito Chiba, Kouichi Konno

The Journal of the Society for Art and Science   12 ( 1 ) 36 - 47   2013年03月  [査読有り]

学会誌  共著・分担

This paper presents a method for extracting and modifying features for illustrating stone tools. Features are detected from unorganized point clouds obtained by a 3D laser scanner. The curvature of each point in the point clouds is estimated by local surface fitting algorithm and used for detecting potential feature points. Feature lines are extracted by directionally growing algorithm. Our directionally feature line growing method is accurate and simple to detect feature lines from unorganized point data. The main idea of our method is to extract feature lines using principal curvatures and principal directions of the potential feature points along the axis directions and to merge all extracted lines. In the illustration of stone tools, to maintain form and manufacturing information, it requires to modify the detected features by specific knowledge on illustrating stone tools. Using the power of data parallel computation on the GPU, our method can be accelerated multiple times. Finally, our experimental results are compared to the actual illustrations drawn by archaeological illustrators.

トリム曲面を用いた土器の欠落形状の表現手法

木下勉，村木祐太，松山克胤，今野晃市

芸術科学会論文誌   11 ( 3 ) 47 - 58   2012年09月  [査読有り]

学会誌  共著・分担

A Study of Surface Fitting Method to an N-sided Region Considering G1-Continuity with Adjacent Surfaces

Y.Muraki, K.Matsuyama, K.Konno, Y.Tokuyama

IWAIT2012     2012年01月  [査読有り]

学会誌  共著・分担

An Examination of Earthenware Restoration System with the Direct Contact to Measured Points

S.Oikawa, K.Matsuyama, K. Konno, Y. Tokuyama

IWAIT2012     2012年01月  [査読有り]

学会誌  共著・分担

A Study of Augmented Exhibition System for Traditional Art Crafts Using Augmented Reality and Force Feedback

S.Sasamura, K.Matsuyama, T.Tanaka, and K. Konno

IWAIT2012     2012年01月  [査読有り]

学会誌  共著・分担

ろうそくの炎の静止画像から炎の揺らぎアニメーションを生成するノイズベースモーフィング

小川優樹，松山克胤，藤本忠博，千葉則茂

芸術科学会論文誌   10 ( 4 ) 276 - 284   2011年12月  [査読有り]

学会誌  共著・分担

MIKAN GLOBE MT: An Interactive World Map featuring Seamless Map Projection and Guaranteed Visibility

Katsutsugu Matsuyama, Makoto Okamoto

The Journal of the Society for Art and Science   8 ( 3 ) 130 - 142   2009年09月  [査読有り]

学会誌  共著・分担

This paper describes the research and development of a new tool for visualizing world maps. The developers anticipate this tool will provide a better grasp of structures and enable an improved understanding of features from multiple viewpoints. The following needs were identified on the basis of interviews with subjects who are likely users of map software: overhead views and true-to-life views; side-by-side comparison of arbitrarily selected locations; and context awareness. The software was designed to satisfy these requirements by incorporating a new algorithm, resulting in a package with distinctly different characteristics from those that are browsed in a directly geometric fashion. In this paper, we propose a viewing system that allows the user to switch seamlessly between different geographical projections and a multi-focus view displaying method by parameter adjustment and split screen. The effectiveness of this approach is validated in a survey of subjects using this mapping software.

Generating Spark Discharge Sound for Interactive Animation using WM-wave

Katsutsugu Matsuyama, Tadahiro Fujimoto, Norishige Chiba

The Journal of the Society for Art and Science   7 ( 4 ) 145 - 154   2008年12月  [査読有り]

学会誌  共著・分担

A technology for automatically creating and adding sound to interactive CG animations of spark discharges in an efficient way has been developed. In the procedure proposed in this paper, the user inputs the electric charge distribution, boundary conditions and other parameters affecting the initiation of electric discharges in virtual space. The animation of the discharge is then created by generating and rendering the profile of the discharge pattern. The sound synchronized with the animation is automatically generated in an efficient way. The noises generated by spark discharges are shock waves, which exhibit complicated behavior; however, in this study, an empirical profile for a shock wave is employed to efficiently generate the acoustic waveform. Effective procedures for expressing lightning discharges and continuous discharges are also proposed.

Real-time animation of spark discharge

Katsutsugu Matsuyama, Tadahiro Fujimoto, Norishige Chiba

The Visual Computer   22 ( 9-11 ) 761 - 771   2006年08月  [査読有り]

学術誌  共著・分担

We have developed a CG technique that creates real-time animations of spark discharges. The technique proposed in this paper has factors related to the generation of a discharge, such as electric charge distribution and boundary conditions in a virtual space as the input, and generates spark discharge shape patterns based on the electric field defined by the input information. An electric field is expressed by the Laplace equation. Our method efficiently obtains the numerical solution of the equation using the calculation technique of the conjugate gradient method implemented on GPU, and can cope with dynamic changes in input. It also produces discharge patterns in both two and three dimensions. In addition, an efficient pseudo-dimensional expansion technique is proposed in this paper, which uses multiple two-dimensional electric fields to generate three-dimensional discharge patterns.

Generation of tree movement sound effects

Katsutsugu Matsuyama, Tadahiro Fujimoto, Kazunobu Muraoka, Norishige Chiba

Computer Animation and Virtual Worlds   16 ( 5 ) 531 - 545   2005年11月  [査読有り]

学術誌  共著・分担

This paper presents a method for automatically generating sound effects for an animation of branches and leaves moving in the wind. Each tree is divided into branches and leaves, and an independent sound effect generation process is employed for each element. The individual results are then compounded into one sound effect. For the branches, we employ an approach based on the frequencies of experimentally obtained Karman vortex streets. For the leaves, we use the leaf blade state as the input and assume a virtual musical instrument that uses wave tables as the sound source. All computations can be performed independently for each frame step. Therefore, each frame step can be executed on completion of the animation step. The results of the implementation of the approach are presented and it is shown that the process offers the possibility of real-time operation through the use of parallel computing techniques.

風による樹木の揺らぎの効果音の効率的な生成法

松山克胤, 藤本忠博, 村岡一信, 千葉則茂

芸術科学会論文誌   3 ( 1 ) 76 - 85   2004年03月  [査読有り]

学会誌  共著・分担

筆者らは、これまで風による樹木の揺らぎの効果音を自動的に付加するサウンドモデリング法を提案している。この提案手法は、樹木の枝と葉に対して、揺らぎの付加と効果音の生成をそれぞれ独立に行い、個々に作成された効果音を合成することで、樹木全体の効果音としている。本論文では、枝と葉の効果音の生成に対して、既提案手法とは異なる統計的なアプローチに基づくより効率的に動作する手法を提案する。