Takeo Igarashi

The University of Tokyo, Tōkyō, Japan

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Publications (213)120.52 Total impact

  • Source
    Masaaki Miki · Takeo Igarashi · Philippe Block
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    ABSTRACT: This paper presents a new computational method for computing funicular, i.e. compression-only, shells, also referred to as self-supporting surfaces (Miki et al. [14]). In this method, both input and output geometries are represented by NURBS, which allows for a precise and smooth controlled form finding without the need of discretization. The method computes an Airy stress function directly by using a commercial optimization engine. The resultant Airy stress functions, which represent possible and continuous horizontal equilibria of the shell of given projection, are also represented by NURBS. In general, though, the NURBS patches are only G 0 continuous at their intersecting edges, which demands that the discontinuity at the edges be solved. To address this, we added ribs to those intersection edges, which basically carry the axial forces along the edge creases. The axial forces in the ribs are computed using the discrete version of Airy stress functions (Fraternali et al. [1]). The same technique was applied to the open (i.e., unsupported boundary) edges to solve boundary equilibrium conditions appropriately. Note that the basic formulations and representative computational results are presented in Miki et al. [14]. This paper aims to supplement Miki et al. [14] and particularly explain a possible design scenario for self-supporting surfaces.
    IASS2015, Amsterdam; 08/2015
  • Source
    Masaaki Miki · Takeo Igarashi · Philippe Block
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    ABSTRACT: This paper presents a method that employs parametric surfaces as surface geometry representations at any stage of a computational process to compute self-supporting surfaces. This approach can be differentiated from existing relevant methods because such methods represent surfaces by a triangulated mesh surface or a network consisting of lines. The proposed method is based on the theory of Airy stress functions. Although some existing methods are also based on this theory, they apply its discrete version to discrete geometries. The proposed method simultaneously applies the theory to parametric surfaces directly and the discrete theory to the edges of parametric patches. The discontinuous boundary between continuous patches naturally corresponds to ribs seen in traditional vault masonry buildings. We use nonuniform rational B-spline surfaces in this study; however, the basic idea can be applied to other parametric surfaces. A variety of self-supporting surfaces obtained by the proposed computational scheme is presented.
    ACM Transactions on Graphics 08/2015; 34(4):89. DOI:10.1145/2766888 · 3.73 Impact Factor
  • Takeo Igarashi · Masahiko Inami
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    ABSTRACT: A robotic system can be considered as a computer with the capability to interact with the real world using sensors and actuators. In this paper, we report our experiences in the development of novel user interfaces for robotic systems, especially in the home environment. We begin with an observation that typical user interfaces for robots are either overly abstract (i.e., gestures or speech) or excessively detailed (i.e., control pad or joystick) for daily use. The proposed approach is to apply techniques developed in the human-computer interaction field, such as augmented reality and tangible user interfaces, to human-robot interaction. We introduce prototype systems such as home appliance control methods using augmented reality, a paper-based method for instructing mobile robots, and various I/O devices to enhance physical interaction with robotic systems. We conclude this paper with the lessons learned from these experiences.
    IEEE Computer Graphics and Applications 01/2015; 35(3). DOI:10.1109/MCG.2015.24 · 1.12 Impact Factor
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    ABSTRACT: An entertainment system. called "RoboJockey" (i.e., a robot jockey), for creating a robot's performances, such as dancing, in a similar manner to a "disc jockey" (DJ) or "video jockey" (VJ), was developed and demonstrated. RoboJockey consists of a multi-touch tabletop interface for multi-user collaboration, and it enables a user to choreograph a robot to dance by using a simple visual language. The visual language has two types of circular objects, namely, robot and action. A robot object represents the real robot, and has a "circulate timeline" around it. RoboJockey supports two types of robots, a simple mobile robot and a humanoid robot. An action object represents the actual actions of robots. With RoboJockey, a user can coordinate the mobile robot's actions with a combination of back, forward, and rotating movements and coordinate the humanoid robot's actions with a combination of arm and leg movements. Every action is automatically performed to background music. RoboJockey was demonstrated at a domestic symposium in Japan, a Japanese national science museum, and an international conference, and the users' behavior at all these venues was observed. In this paper, we report the results of the observations and discuss the entertainment experience that RoboJockey gave to the users.
    IEEE Computer Graphics and Applications 01/2015; DOI:10.1109/MCG.2015.1 · 1.12 Impact Factor
  • Jun Kato · Daisuke Sakamoto · Takeo Igarashi · Masataka Goto
    Proceedings of the Second International Conference on Human-agent Interaction, Tsukuba, Japan; 10/2014
  • Source
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    ABSTRACT: This paper presents an extension to the existing dynamic relaxation method to include equality constraint conditions in the process. The existing dynamic relaxation method is presented as a general, gradient-based, minimization technique. This representation allows for the introduction of the projected gradient, discrete parallel transportation and pull back operators that enable the formulation of the geodesic dynamic relaxation method, a method that accounts for equality constraint conditions. The characteristics of both the existing and geodesic dynamic relaxation methods are discussed in terms of the system's conservation of energy, damping (viscous, kinetic, and drift), and geometry generation. Particular attention is drawn to the introduction of a novel damping approach named drift damping. This technique is essentially a combination of viscous and kinetic damping. It allows for a smooth and fast convergence rate in both the existing and geodesic dynamic relaxation processes. The case study was performed on the form-finding of an iconic, ridge-and-valley, pre-stressed membrane system, which is supported by masts. The study shows the potential of the proposed method to account for specified (total) length requirements. The geodesic dynamic relaxation technique is widely applicable to the form-finding of force-modeled systems (including mechanically and pressurized pre-stressed membranes) where equality constraint control is desired. Copyright © 2014 John Wiley & Sons, Ltd.
    International Journal for Numerical Methods in Engineering 08/2014; 99(9). DOI:10.1002/nme.4713 · 1.96 Impact Factor
  • Article: Pteromys
    Nobuyuki Umetani · Yuki Koyama · Ryan Schmidt · Takeo Igarashi
    ACM Transactions on Graphics 07/2014; 33(4):1-10. DOI:10.1145/2601097.2601129 · 3.73 Impact Factor
  • Takashi Ijiri · Shin Yoshizawa · Hideo Yokota · Takeo Igarashi
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    ABSTRACT: This paper presents a novel three dimensional (3D) flower modeling technique that utilizes an X-ray computed tomography (CT) system and real-world flowers. Although a CT system provides volume data that captures the internal structures of flowers, it is difficult to accurately segment them into regions of particular organs and model them as smooth surfaces because a flower consists of thin organs that contact one another. We thus introduce a semi-automatic modeling technique that is based on a new active contour model with energy functionals designed for flower CT. Our key idea is to approximate flower components by two important primitives, a shaft and a sheet. Based on our active contour model, we also provide novel user interfaces and a numerical scheme to fit these primitives so as to reconstruct realistic thin flower organs efficiently. To demonstrate the feasibility of our technique, we provide various flower models reconstructed from CT volumes.
    ACM Transactions on Graphics 07/2014; 33(4):1-10. DOI:10.1145/2601097.2601124 · 3.73 Impact Factor
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    ABSTRACT: Computer displays play an important role in connecting the information world and the real world. In the era of ubiquitous computing, it is essential to be able to access information in a fluid way and non-obstructive integration of displays into our living environment is a basic requirement to achieve it. Here, we propose a display technology that utilizes the phenomenon whereby the shading properties of fur change as the fibers are raised or flattened. One can erase drawings by first flattening the fibers by sweeping the surface by hand in the fiber's growth direction and then draw lines by raising the fibers by moving a finger in the opposite direction. These material properties can be found in various items such as carpets and plush toy in our living environment. Our technology can turn these ordinary objects into displays without requiring or creating any non-reversible modifications to the objects. It can be used to make a large-scale display and the drawings it creates have no running costs.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Computer displays play an important role in connecting the information world and the real world. In the era of ubiquitous computing, it is essential to be able to access information in a fluid way and non-obstructive integration of displays into our living environment is a basic requirement to achieve it. Here, we propose a display technology that utilizes the phenomenon whereby the shading properties of fur change as the fibers are raised or flattened. One can erase drawings by first flattening the fibers by sweeping the surface by hand in the fiber's growth direction and then draw lines by raising the fibers by moving a finger in the opposite direction. These material properties can be found in various items such as carpets and plush toy in our living environment. Our technology can turn these ordinary objects into displays without requiring or creating any non-reversible modifications to the objects. It can be used to make a large-scale display and the drawings it creates have no running costs.
  • Jun Kato · Takeo Igarashi
    Proceedings of the 2014 Graphics Interface Conference, Montreal, Quebec, Canada; 05/2014
  • Makoto Nakajima · Daisuke Sakamoto · Takeo Igarashi
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    ABSTRACT: We present an animation creation workflow for integrating offline physical, painted media into the digital authoring of Flash-style animations. Generally, animators create animations with standardized digital authoring software. However, the results tend to lack the individualism or atmosphere of physical media. In contrast, illustrators have skills in painting physical media but have limited experience in animation. To incorporate their skills, we present a workflow that integrates the offline painting and digital animation creation processes in a labor-saving manner. First, a user makes a rough sketch of the visual elements and defines their movements using our digital authoring software with a sketch interface. Then these images are exported to printed pages, and users can paint using offline physical media. Finally, the work is scanned and imported back into the digital content, forming a composite animation that combines digital and physical media. We present an implementation of this system to demonstrate its workflow. We also discuss the advantages of using physical media in digital animations through design evaluations.
  • Koumei Fukahori · Daisuke Sakamoto · Jun Kato · Takeo Igarashi
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    ABSTRACT: Programmers write and edit their source code in a text editor. However, when they design the look-and-feel of a game application such as an image of a game character and an arrangement of a button, it would be more intuitive to edit the application by directly interacting with these objects on a game window. Although modern game engines realize this facility, they use a highly structured framework and limit what the programmer can edit. In this paper, we present CapStudio, a development environment for a visual application with an interactive screencast. A screencast is a movie player-like output window with code editing functionality. The screencast works with a traditional text editor. Modifications of source code in the text editor and visual elements on the screencast will be immediately reflected on each other. We created an example application and confirmed the feasibility of our approach.
  • Fangzhou Wang · Yang Li · Daisuke Sakamoto · Takeo Igarashi
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    ABSTRACT: One of the difficulties with standard route maps is accessing to multi-scale routing information. The user needs to display maps in both a large scale to see details and a small scale to see an overview, but this requires tedious interaction such as zooming in and out. We propose to use a hierarchical structure for a route map, called a "Route Tree", to address this problem, and describe an algorithm to automatically construct such a structure. A Route Tree is a hierarchical grouping of all small route segments to allow quick access to meaningful large and small-scale views. We propose two Route Tree applications, "RouteZoom" for interactive map browsing and "TreePrint" for route information printing, to show the applicability and usability of the structure. We conducted a preliminary user study on RouteZoom, and the results showed that RouteZoom significantly lowers the interaction cost for obtaining information from a map compared to a traditional interactive map.
    Proceedings of the 19th international conference on Intelligent User Interfaces; 02/2014
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    ABSTRACT: We present a series of projects for end-user authoring of interactive robotic behaviors, with a particular focus on the style of those behaviors: we call this approach Style-by-Demonstration (SBD). We provide an overview introduction of three different SBD platforms: SBD for animated character interactive locomotion paths, SBD for interactive robot locomotion paths, and SBD for interactive robot dance. The primary contribution of this article is a detailed cross-project SBD analysis of the interaction designs and evaluation approaches employed, with the goal of providing general guidelines stemming from our experiences, for both developing and evaluating SBD systems. In addition, we provide the first full account of our Puppet Master SBD algorithm, with an explanation of how it evolved through the projects.
    01/2014; 3(4). DOI:10.1145/2499671
  • Conference Paper: Graffiti fur
    ACM SIGGRAPH 2014 Emerging Technologies; 01/2014
  • Conference Paper: Graffiti fur
    ACM SIGGRAPH 2014 Studio; 01/2014
  • Daniel Saakes · Thomas Cambazard · Jun Mitani · Takeo Igarashi
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    ABSTRACT: The availability of low-cost digital fabrication devices enables new groups of users to participate in the design and fabrication of things. However, software to assist in the transition from design to actual fabrication is currently overlooked. In this paper, we introduce PacCAM, a system for packing 2D parts within a given source material for fabrication using 2D cutting machines. Our solution combines computer vision to capture the source material shape with a user interface that incorporates 2D rigid body simulation and snapping. A user study demonstrated that participants could make layouts faster with our system compared with using traditional drafting tools. PacCAM caters to a variety of 2D fabrication applications and can contribute to the reduction of material waste.
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    ABSTRACT: We present faceton, a geometric modeling primitive designed for building architectural models, using a six degrees of freedom (DoF) input device in a virtual environment (VE). A faceton is given as an oriented point floating in the air and defines a plane of infinite extent passing through the point. The polygonal mesh model is constructed by taking the intersection of the planes associated with the facetons. With the simple drag-and-drop and group interaction of faceton, users can easily create 3D architecture models in the VE. The faceton primitive and its interaction reduce the overhead associated with standard polygonal mesh modeling in VE, where users have to manually specify vertexes and edges which could be far away. The faceton representation is inspired by the research on boundary representations (B-rep) and constructive solid geometry (CSG), but it is driven by a novel adaptive bounding algorithm and is specifically designed for the 3D modeling activities in an immersive virtual environment.
    Proceedings of the 19th ACM Symposium on Virtual Reality Software and Technology; 10/2013
  • L. Zhu · T. Igarashi · J. Mitani
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    ABSTRACT: We introduce soft folding, a new interactive method for designing and exploring thin‐plate forms. A user specifies sharp and soft folds as two‐dimensional(2D) curves on a flat sheet, along with the fold magnitude and sharpness of each. Then, based on the soft folds, the system computes the three‐dimensional(3D) folded shape. Internally, the system first computes a fold field, which defines local folding operations on a flat sheet. A fold field is a generalization of a discrete fold graph in origami, replacing a graph with sharp folds with a continuous field with soft folds. Next, local patches are folded independently according to the fold field. Finally, a globally folded 3D shape is obtained by assembling the locally folded patches. This algorithm computes an approximation of 3D developable surfaces with user‐defined soft folds at an interactive speed. The user can later apply nonlinear physical simulation to generate more realistic results. Experimental results demonstrated that soft folding is effective for producing complex folded shapes with controllable sharpness.
    Computer Graphics Forum 10/2013; 32(7). DOI:10.1111/cgf.12224 · 1.60 Impact Factor

Publication Stats

2k Citations
120.52 Total Impact Points

Institutions

  • 2003–2015
    • The University of Tokyo
      • Department of Computer Science
      Tōkyō, Japan
  • 2014
    • Université du Québec à Montréal
      Montréal, Quebec, Canada
  • 2009–2012
    • Keio University
      • Graduate School of Media Design
      Edo, Tōkyō, Japan
    • RIKEN
      Вако, Saitama, Japan
  • 2011
    • University of Manitoba
      Winnipeg, Manitoba, Canada
    • The University of Calgary
      Calgary, Alberta, Canada
  • 2009–2010
    • Japan Science and Technology Agency (JST)
      Edo, Tōkyō, Japan
  • 2001–2009
    • Brown University
      • Department of Computer Science
      Providence, Rhode Island, United States
  • 2006–2008
    • Sony Computer Science Laboratories, Inc.
      Edo, Tōkyō, Japan