Takeo Igarashi

The University of Tokyo, Tōkyō, Japan

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Publications (222)161.62 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A shape matching dynamics (SMD) is a robust and efficient elastic model based on geometric constraints. This article introduces our study [1] that adopts SMD to visual simulation of cardiac beating motion. In our technique, a heart is represented by a tetrahedral mesh model and a local region is defined at each vertex by connecting its immediate neighbors. During the simulation, we first contract all local regions depending on predefined muscle fiber orientations and contraction rate. Then using SMD, we compute the global shape of the heart model so that it satisfies the contracted local regions. Our technique introduces a fiber-orientation-dependent weighting function to emulate an anisotropic stiffness of myocardium. Since our technique is based on SMD, it is possible to compute cardiac motion in real-time on a commercially available PC. © 2015, Japan Soc. of Med. Electronics and Biol. Engineering. All rights reserved.
    No preview · Article · Oct 2015
  • Article: AutoConnect

    No preview · Article · Oct 2015 · ACM Transactions on Graphics
  • 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.
    Full-text · Conference Paper · Aug 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.
    Full-text · Article · Aug 2015 · ACM Transactions on Graphics
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    ABSTRACT: Recent digital fabrication tools have opened up accessibility to personalized rapid prototyping; however, such tools are limited to product-scale objects. The materials currently available for use in 3D printing are too fine for large-scale objects, and CNC gantry sizes limit the scope of printable objects. In this paper, we propose a new method for printing architecture-scale objects. Our proposal includes three developments: (i) a construction material consisting of chopsticks and glue, (ii) a handheld chopstick dispenser, and (iii) a printing guidance system that uses projection mapping. The proposed chopstickglue material is cost effective, environmentally sustainable, and can be printed more quickly than conventional materials. The developed handheld dispenser enables consistent feeding of the chopstickglue material composite. The printing guidance system - consisting of a depth camera and a projector evaluates a given shape in real time and indicates where humans should deposit chopsticks by projecting a simple color code onto the form under construction. Given the mechanical specifications of the stickglue composite, an experimental pavilion was designed as a case study of the proposed method and built without scaffoldings and formworks. The case study also revealed several fundamental limitations, such as the projector does not work in daylight, which requires future investigations.
    No preview · Article · Jul 2015 · ACM Transactions on Graphics
  • 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.
    No preview · Article · Jan 2015 · IEEE Computer Graphics and Applications
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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.
    No preview · Article · Jan 2015 · IEEE Computer Graphics and Applications
  • Jun Kato · Daisuke Sakamoto · Takeo Igarashi · Masataka Goto

    No preview · Conference Paper · Oct 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.
    Full-text · Article · Aug 2014 · International Journal for Numerical Methods in Engineering
  • Article: Pteromys
    Nobuyuki Umetani · Yuki Koyama · Ryan Schmidt · Takeo Igarashi

    No preview · Article · Jul 2014 · ACM Transactions on Graphics
  • 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.
    No preview · Article · Jul 2014 · ACM Transactions on Graphics
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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.
    No preview · Article · Jul 2014
  • [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.
    No preview · Article · Jul 2014
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    ABSTRACT: In this paper, we propose an electric power management system for delivering power to home appliances with mobile robots. With our system, the user places an appliance without power cables freely within the home, and a robot provides the appliance with the electric power required for its operation. In addition to providing explanations of a usage scenario and a theoretical analysis, we demonstrate a prototype implementation. The robot of the prototype autonomously locates the target appliance, transfers its battery power to the appliance, and returns to the home position to recharge its battery. The validation study showed our proof-of-concept prototype worked as expected by the theory.
    No preview · Conference Paper · May 2014
  • Jun Kato · Takeo Igarashi
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    ABSTRACT: We propose an integrated development environment (IDE) called "VisionSketch", which supports example-centric programming for easily building image processing pipelines. With VisionSketch, a programmer is first asked to select the input video. Then, he can start building the pipeline with a visual programming language that provides immediate graphical feedback for algorithms applied to the video. He can also use a text-based editor to create or edit the implementation of each algorithm. During the development, the pipeline is always ready for execution with a video player-like interface enabling rapid iterative prototyping. In a preliminary user study, VisionSketch was positively received by five programmers, who had prior experience of writing text-based image processing programs and could successfully build interesting applications.
    No preview · Conference Paper · May 2014
  • 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.
    No preview · Article · Apr 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.
    No preview · Article · Apr 2014
  • 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.
    No preview · Conference Paper · Feb 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.
    No preview · Article · Jan 2014 · The ACM Transactions on Interactive Intelligent Systems
  • Conference Paper: Graffiti fur

    No preview · Conference Paper · Jan 2014

Publication Stats

3k Citations
161.62 Total Impact Points

Institutions

  • 2003-2015
    • The University of Tokyo
      • Department of Computer Science
      Tōkyō, Japan
  • 2009-2012
    • Keio University
      • Graduate School of Media Design
      Edo, Tōkyō, Japan
    • RIKEN
      Вако, Saitama, Japan
  • 2011
    • The University of Calgary
      • Department of Computer Science
      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
  • 2006-2007
    • Sony Computer Science Laboratories, Inc.
      Edo, Tōkyō, Japan