Hiroshi Masuda

The University of Tokyo,
The Graduate School of Engineering

7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

        Japanese Page (研究室紹介のページ)         Publication (Japanese) (論文等の資料)

Research Interests


Publications and Download (English Only)

Research Topicss

[Surface Reconstruction]

A Streaming Surface Generator for Noisy Large-Scale Point Data

Recently, the 3D shape acquisition of large facilities, such as industry plants and power plants, has gained increasing attention for simulating complicated tasks in maintenance and repair. In this research, we developed a new robust surface generator for very noisy point-clouds in a streaming manner. Recent phase-based laser scanners output hundreds of millons of noisy points in several minutes. Our method can successfully generate high quality mesh models using such large-scale point-clouds.

[ Mesh Editing ]

Interactive Deformation of 3D Mesh Models
Hiroshi Masuda and Kenta Ogawa

This paper proposes a framework for interactively deforming 3D mesh models. In our framework, all constraints are represented in linear forms and solved very efficiently using sparse linear system solvers.

[1] Feature-Preserving Deformation for Assembly Models (pdf)
Hiroshi Masuda , Computer-Aided Design and Applications ( CAD'07 ), June 25-29, 2007
[2] Application of Interactive Deformation to Assembled Mesh Models for CAE Analysis (pdf)
Hiroshi Masuda and Kenta Ogawa , ASME International Design Engineering Technical Conferences ( IDETC/DAC ), Las Vegas, Nevada, USA, Sep. 3-7, 2007.

Mesh deformation, which is sometimes referred to as mesh morphing in CAE, is useful for providing various shapes of meshes for CAE tools. This paper proposes a new framework for interactively and consistently deforming assembly models, which consist of multiple disconnected meshes.
Paper [1] proposes a method based on mean-value coordinates; [2] is based on additional constraints. Paper[2] also proposes a method to handle non-manifold conditions in surface-based deformation.

Preserving Form-Features in Interactive Mesh Deformation (pdf)
Hiroshi Masuda, Yasuhiro Yoshioka, Yoshiyuki Furukawa, LNCS 4077 ( Geometric Modeling and Processing 2006 ) pp.207-220 , Pittsburgh, USA, July 26-18, 2006.

Mesh editing that maintains differential properties allows the interactive modification while preserving the details of shapes. Although product design often requires that dimensions and surface types are strictly satisfied during deformation processes, previous methods lack the ability to manipulate constraints of form-features. This paper proposes a novel framework for interactive mesh editing in which form-features are incorporated using hard constraints. In our constraint-settings, form-features can be translated and rotated according to the motion of handles while maintaining the original shapes. The implemented system can achieve a real-time response.

A Constrained Least Squares Approach to Interactive Mesh Deformation (pdf)
Yasuhiro Yoshioka, Hiroshi Masuda, Yoshiyuki Furukawa
IEEE International Conference on Shape Modeling and Applications, pp.153-162, Matsushima, Japan, June 14-16, 2006

We propose a constrained least squares approach for stably computing Laplacian deformation with strict positional constraints. We solve the combination of hard and soft constraints by constructing a typical least squares matrix form using QR decomposition. A significant benefit of this approach is the resolution of over-constraints. When shapes are constrained using soft and hard constraints, the user needs to carefully avoid the redundancy of hard constraints, because redundant hard constraints cause rank deficiency problems. QR decomposition is suitable for detecting and removing such over-constraints.

Volume-Based Cut-and-Paste Editting For Early Design Phases (pdf)
Hiroshi Masuda, Yoshiyuki Furukawa, Yasuhiro Yoshioka, ASME Design Engineering Technical Conferences and Computers and Information in Engineering Conference, September 28-October 2, 2004, Salt Lake City, Utah USA

We propose modeling operations based on a volume-based cut-and-paste method. Our method allows pasting a wide variety of features that may have overhangs and handles. To realize such a volume-based cut-and-paste technique, this paper introduces a new method based on surface/volume fitting.

[ Geometry Compression]

Compression of NURBS Surfaces with Error Evaluation (pdf)
Yoshiyuki Furukawa and Hiroshi Masuda, NICOGRAPH Internatinal, May 2002

This paper proposes a compression method for NURBS surfaces. In our method, a NURBS surface is encoded using its boundary and two types of difference data. In the first step, boundary curves are extracted from the original surface and an approximate surface that interpolates boundary curves is calculated. In the next step, the differences between correspondent control points are calculated by comparing to the original surfaces. The differences are represented using distances only, or distances and orientations according to the accuracy needed by receivers. Finally, the boundary curves and the differences are compressed using DCT.

Coding Topological Structure of 3D CAD Models (pdf)
Hiroshi Masuda, Ryutaro Ohbuchi, Computer-Aided Design, Vol.32, No.5-6, May-June 2000

This paper proposes a loss-less method to encode and compress three-dimensional (3D) geometric models which may contain non-simple topological structures. Any combination of wireframe, surface, and solid components can be encoded and compressed by the method. Furthermore, our method is able to handle models that contain various non-simple topological structures that are likely to exist models generated by using 3D Computer Aided Design (CAD) systems. The topological transformation is performed by applying a sequence of Euler operators to the given model. Both the transformation operation and the reduced model are encoded and compresed to produce compressed data.

[ Watermarking ]

Watermarking Three-Dimensional Polygonal Models Through Geometric and Topological Modifications (pdf)
Ryutaro Ohbuchi, Hiroshi Masuda, Masaki Aono, IEEE Journal on Selected Areas in Communications, Vol. 16, No. 4, May 1998

This paper discusses method for embedding data into three-dimensional (3D) polygonal models of geometry. Given objects consisting of points, lines, polygons, or curved surfaces, the data embedding algorithms described in this paper produce polygonal models with data embedded. Data are placed into 3D polygonal models by modifying either their vertex coordinates, their vertex topology (connectivity), or both. A brief review of related work and a description of the requirements of data embedding is followed by a discussion of where, and by what fundamental methods, data can be embedded into 3D polygonal models. The paper then presents data-embedding algorithms, with examples, based on these fundamental methods.

[ Solid Modeling ]

A Cell-Based Approach for Generating Solid Objects from Orthographic Projections (pdf)
Hiroshi Masuda and Masayuki Numao, Computer-Aided Design, Vol.29, No.3, March 1997

This paper describes an efficient method for converting orthographic projections to solid models. We show a combination of non-manifold modeling and ATMS achieves excellent performance for conversion problems. In our method, all solid candidates are maintained by a cellular model using non-manifold topology. Since a combination of cells in a cellular model determines a solid shape, proper solids can be derived by solving constraints between cells and orthographic projections. Sufficient constraints can be expressed as a set of Boolean equations, and they are solved efficiently by using ATMS. In addition, our method is so flexible that it can be applied to incorrect draftings. When draftings have inconsistent lines and missing lines, solutions are searched for by adding supplementary lines and loosening constraints.

Topological Operators and Boolean Operations for Complex-Based Non-Manifold Geometric Models (pdf)
Hiroshi Masuda, Computer-Aided Design, Vol.25, No.2, Feb. 1993.

Non-manifold geometric modelling is used to represent and manipulate wireframe, surface, and solid models in a single architecture. It is suitable for improving geometric modelling environments for product design. In this paper, first, some fundamentals of non-manifold geometric modelling are presented. A mathematical framework is introduced and the topological structure and basic topological operations are discussed on the basis of the framework. Next, a new method, which can quickly and arbitrarily reshape geometric models defined by Boolean operations, is presented. This method is made possible by the capabilities of non-manifold geometric modelling, and can be used for design by trial and error and form-feature modelling.

A Mathematical Theory and Applications of Non-Manifold Geometric Modeling (pdf)
Hiroshi Masuda, Kenji Shimada, Masayuki Numao, and Shinji Kawabe, IFIP WG 5.2/GI International Symposium on Advanced Geometric Modeling for Engineering Applications, North-Holland, pp.89-103, Berlin , Germany, November 1898

We present a non-manifold geometric modeling system that can manipulate wireframe, surface, and solid models in a single architecture. We first introduce a mathematical framework for characterizing non-manifold geometric models, and then discuss the characteristics of non-manifold geometric modeling in the basis of the mathematical framework; in particular, we propose new Euler operations that are suitable for manipulating topological data. To prove the effectiveness of non-manifold geometric models for improving of a 3D modeling environment, we present a rapid and flexible method of reshaping solid models allowed by hybrid CSG/B-rep modeling, based on non-manifold geometric modeling.