Refereed Publications

1. I. Semenova, V. Savchenko, and I. Hagiwara, “A New Approach for Improvement of Polygonal Meshes Representing Surfaces with Sharp Edges and Boundaries,” JSME International Journal Published by The Japan Society of Mechanical Engineers, Vol. 48, No. 2, June, 2005, pp. 122-129
   Abstract - In this paper, we introduce a new approach to surface mesh improvement problem. In contrast to previous methods we do not tend to preserve new mesh vertices on the original discrete surface. Instead our technique keeps mesh nodes very close to a smooth or piecewise-smooth surface approximated by the initial mesh. As a result, the algorithm is able to improve mesh quality while preserving essential surface characteristics and features. Proposed approach can be applied iteratively not only to polygonal meshes but also to 2D and 3D curves that allows to treat sharp edges and surface boundaries. We demonstrate effectiveness of our method using various triangular and quadrilateral meshes. Also we compare our algorithm with some commonly used techniques and analyze their advantages and disadvantages.
2. M. Savchenko, O. Egorova, V. Savchenko, I. Hagiwara, and V. Savchenko, “Hexahedral Mesh Improvement Algorithm,” JSME International Journal Published by The Japan Society of Mechanical Engineers, Vol. 48, No. 2, June, 2005, pp. 130-136
   Abstract - In this paper, we present a novel method, based on an implementation of quasi-statistical modeling, for improving hexahedral solid meshes. A method for improving meshes by producing elements with a Gaussian (normal) distribution of the mesh quality parameter values is discussed. The main intention is to attain a fairly smooth change from one mesh element to another without creating a significant difference between the shapes of neighboring elements. As regards the initial distribution of the mesh quality parameter values, we assume that after improvement the distribution varies from a rather random distribution to a smoother one, such as a normal distribution. The preliminary choice of the desirable distribution affects the new parameter values modeled by the formula presented here. Our method can be used in a pre-processing stage for subsequent studies (finite element analysis, computer graphics, etc.) by providing better input parameters for these processes. Experimental results are included to demonstrate the functionality of our method.
3. M. Savchenko, O. Egorova, I. Hagiwara, and V. Savchenko, “An Approach to Improving Triangular Surface Mesh,”JSME International Journal Published by The Japan Society of Mechanical Engineers, Vol. 48, No. 2, June, 2005, pp. 137-148
   Abstract - Our method is based on an implementation of quasi-statistical modeling for improving meshes by producing mesh elements with modeled values of different mesh quality parameters. In this paper we implement this approach to triangular surface mesh. Considering the initial distribution of the mesh quality parameter values, we assume that after improvement the distribution of elements of the mesh varies from a rather random distribution to a smoother one, such as a normal distribution. The preliminary choice of the desirable distribution affects the new parameter values modeled by the formula presented here. Uncertainty of the smoothed vertex positions of the mesh element affords to use a statistical approach in sense of random variable modeling to connect quasi-statistical modeling and mesh improvement techniques. The so-called “kernel” method allows creating different applicable to a mesh processing algorithms, which can be interpreted as a kind of smoothing technique to determine vertex direction movement with the distribution control of the shape of mesh elements. An aspect ratio is mainly used in present research as a mesh quality parameter. The geometry of the initial mesh surface is preserved by local mesh improving such that the new positions of the interior nodes of the mesh remain on the original discrete surface. Our method can be interpreted as a kind of smoothing technique with using the distribution control of the mesh quality parameter values. This method is comparable with optimization-based approach for avoiding the invalid elements of the mesh by producing a mesh with a rather homogeneous distribution of the mesh elements. Experimental results are included to demonstrate the functionality of our method. The method can be used at a pre-process stage for subsequent studies (finite element analysis, computer graphics, etc.) by providing the better-input parameters for these processes.
4. V. Savchenko, “2D Local Sample-Based Interpolation as a Tool for Approximation of 3D Point Sets,” JSME International Journal Published by The Japan Society of Mechanical Engineers, Vol. 48, No. 2, June, 2005, pp. 176-183
   Abstract - We describe a novel algorithm for local approximation of scattered surface points, implementing a 2D finite element interpolation algorithm in combination with approximation of coordinates using quadrics for conversion of noisy data to sufficiently smooth data sets. The applied methods and time performance of the developed algorithm are discussed. Experimental results are included to demonstrate the functionality of our approximation technique.
5. V. Savchenko, “Trends and Solutions in CAD/CG,” JSME International Journal Published by The Japan Society of Mechanical Engineers, Vol. 48, No. 2, June, 2005, pp. 184-196
   Abstract - Past and current trends in CAD/CG are discussed. An overview of the approach used in our ongoing project is given. Our final goal is primarily focused on developing a shape modeling system for solving problems of surface generation and enhancement, which includes polygon generation from unorganized points, shape smoothing, simplification, and improvement of mesh quality parameters of 3D polygonal sets.
6. Semenova, V. Savchenko, I. Hagiwara, “Reconstruction of Shapes Based on Normals Analysis,” Proceedings 15th International Conference on Computer Graphics and Vision (Graphicon`2005), June 20-24, 2005, pp. 125-131
   Abstract - Most mesh processing filters (including remeshing, simplification, and subdivision) affect vertices of the mesh. Vertices coordinates are modified, new vertices are added and some original ones are removed, with the result that the shape of the original surface is changed. While a great deal of research is concentrated on preservation of surface shape during some mesh processing, there is no general tool that can be used for surface reconstruction at post processing stage. To the best of our knowledge, this paper is the first one to present a restoring algorithm that allows to “repair” output of various mesh processing filters. The proposed scheme is straightforward way to put “off-surface” vertices of the deformed mesh back to the original smooth shape. It does not require any surface parameterization and is based on normal analysis. The procedure is demonstrated by using it as post processing tool after applying local node movement and simplification algorithms. However, the technique is versatile enough to be used in a large variety of mesh optimization algorithms including remeshing and subdivision schemes.
7. D. Yamazaki and V. Savchenko, “Physically-based Visual Simulation of Comets in Virtual Environments Modeling the Solar System,” Proceedings of the IASTED Eighth International Conference COMPUTERS and ADVANCED TECHNOLOGY in EDUCATION, Oranjestad, Aruba, Aug 29-31, 2005, pp. 171-176
   Abstract - Visual simulation of various natural phenomena is one of the most important research fields in computer graphics. Simulations with physical correctness are useful to improve computer graphics images with more realistic rendering results. In addition, such simulations let people understand phenomena exactly and easily, and therefore play an important role in educational fields. In this article we present a simulation system for comet behavior in virtual environments such as a model of Solar System with moving comets. The purpose of our system is to visualize results of the simulation of whole phenomena of comets, including the evaporation process, the process of the coma generation, and dynamically changing tails influenced by the surrounding environment.
8. I. Semenova, N. Kozhekin, V. Savchenko, and I. Hagiwara , “A General Framework for Analysis and Comparison of Surface Mesh Optimization Techniques,” Engineering with Computers, Springer-Verlag London Ltd , ISSN: 0177-0667 (Paper), 1435-5663 (Online),
   DOI: 10.1007/s00366-005-0305-y ,Vol. 21, No, 2, December 2005, pp. 91 - 100
   Abstract - Many different algorithms for surface mesh optimization (including smoothing, remeshing, simplification and subdivision), each giving different results, have recently been proposed. All these approaches affect vertices of the mesh. Vertex coordinates are modified, new vertices are added and some original ones are removed, with the result that the shape of the original surface is changed. The important question is how to evaluate the differences in shape between the input and output models. In this paper, we present a novel and versatile framework for analysis of various mesh optimization algorithms in terms of shape preservation. We depart from the usual strategy by measuring the changes in the approximated smooth surfaces rather than in the corresponding meshes. The proposed framework consists of two error metrics: normal-based and physically based. We demonstrate that our metrics allow more subtle changes in shape to be captured than is possible with some commonly used measures.

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