白木 厚司

Since virtual reality technology can easily realize a particular environment, it has been applied to various training. This technology is also expected in education such as those dealing with three-dimensional figures because they can represent phenomena in three dimensions. One of the standard virtual reality technologies is wearing a head-mounted display to experience a virtual reality project. However, the virtual reality experience is limited to the person wearing the head-mounted display (in most cases) when considering the use of head-mounted display-based virtual reality in education, making its usage unsuitable for mass education. Therefore, in this study, we develop a second-screen system that can share virtual reality information using an Android device. Healthy first- and second-year high school students between the ages of 15 and 17 were asked to use the virtual reality educational materials that implemented the developed system, and a questionnaire survey was conducted. There were no negative comments in the survey on whether proposing second-screen system was necessary, demonstrating the usefulness of the proposed system. Therefore, the second-screen system may adapt VR technology to mass education. In addition, we developed a package to integrate our second-screen system into the pre-existing virtual reality projects. This package simplifies the procedure for implementing a second-screen system, thus helping to reuse the virtual reality projects that have been developed so far.

This study introduces a diffraction calculation that utilizes low-quantization input images and impulse responses. Quantization of signals enables more efficient calculations. The proposed method produces outcomes that are comparable to those achieved with floating-point formats.

This study proposes the use of low-quantization techniques, hexagonal sampling, and implicit convolution to enable lighter and more memory-efficient diffraction calculations. The combination of these methods reduces memory usage and speeds up diffraction calculations.

超スマート社会実現のために膨大な数のIoT機器の配備が不可欠であり，そのセキュアなIoTサービスの利用には機器識別技術が重要である．攻撃に強いディジタル識別子を活用する技術として物理複製困難関数（PUF）が注目されているが，これは多くのケースで専用のハードウェア機構を要求する．クロックフィンガープリントはクロック発信器に由来するPUFの一種で，その固有の特徴量をコンピュータが必ず利用するシステム時刻から得ることができるため，ソフトウェアのみの実装で適用できる点が特徴である．そのため，設置された既存の機器や低コスト性の求められる製品などに対しても適用可能なので，幅広いコンピュータ機器の識別基盤技術として有望である．本研究はこのクロックフィンガープリントを用いて，単位時間あたりのシステム時刻偏差とCPUコア温度の相関から回帰係数を導出し，これを平均2乗誤差分析によって機器を識別する手法を考案した．実験では6台のネットワーク上のコンピュータから取得した特徴を用いて識別を達成し，併せて訓練データ数の増加とともに回帰係数の精度が向上することを確認した．

This study proposes a dynamic-range compression for digital holograms generated from three-dimensional scenes using deep neural network (DNN). This method uses an error diffusion algorithm to binarize holograms with an 8-bit gradation; moreover, the DNN predicts the original gradation holograms from binary holograms. This method’s performance exceeds that of JPEG 2000 and high-efficiency video coding.

We propose the use of the binary amplitude of a diffracted field to obtain complex-amplitude encoding of a phase-only hologram. Although the complex amplitude in the hologram plane consists of an amplitude and phase, a phase-only hologram retains only the phase information of the complex amplitude, which degrades the quality of the holographic reconstruction. The proposed method approximates the amplitude in the hologram plane by a binary amplitude, which allows us to record the complex amplitude of the original optical field in a phase-only hologram. We verified the effectiveness of the method by applying it to two examples: a hologram reconstruction and the generation of Hermite-Gaussian beams.

We present a new refraction-based approach to embed multiple images into a single volume structure rendered on a glass solid (3D crystal). Each of the images can only be revealed when looked at from the certain viewpoint. While configurations of viewing directions in conventional methods are limited, our method can compensate for refractive effects at glass surfaces regardless of the viewing directions and enable the viewing directions to be set more flexibly, even allowing for 180 ∘ opposite projection by leveraging refraction. These unique features are verified with prototyping of 3D crystals projecting multiple grey-scale images and numerical assessments. In addition, we present a color dynamic representation of our method with computer graphics to demonstrate the potential use of our method as a novel information service system.

In this study, we attempted GPU acceleration of an algorithm to design a directional volumetric display. As a result, the GPU implementation was up to 45 times faster than the CPU implementation. We also confirmed that the GPU implementation could cooperate with a person tracking system in real-time.

In previous study, we developed the directional volumetric display which can display multiple images in different directions. In this study, we implemented a method of person tracking for the directional volumetric display to enable transmitting images and sounds following person using motion capture.

We developed a directional volumetric display that exhibits different images depending on the viewing direction. The display can be expected to be applied to multilingual signage that transmits information in different languages. In this study, we develop a display that exhibits images according to the language used by the observer.

Holography is a method of recording and reproducing three-dimensional (3D) images, and the widespread availability of computers has encouraged the development of holographic 3D screens (electroholography). However, the technology has not yet been used in practical applications because a hologram requires an enormous volume of data and modern computing power is inadequate to process this volume of data in real time. Here, we show that a special-purpose holography computing board, which uses eight large-scale field-programmable gate arrays, can be used to generate 10(8)-pixel holograms that can be updated at a video frame rate. With our approach, we achieve a parallel operation of 4,480 hologram calculation circuits on a single board, and by clustering eight of these boards, we can increase the number of parallel calculations to 35,840. Using a 3D image composed of 7,877 points, we show that 108-pixel holograms can be updated at a video rate, thus allowing 3D movies to be projected. We also demonstrate that the system speed scales up in a linear manner as the number of parallel circuits is increased. The system operates at 0.25 GHz with an effective speed equivalent to 0.5 petaflops (10(15) floating-point operations per second), matching that of a high-performance computer.

Computational ghost imaging (CGI) is a single-pixel imaging technique that exploits the correlation between known random patterns and the measured intensity of light transmitted (or reflected) by an object. Although CGI can obtain two-or three-dimensional images with a single or a few bucket detectors, the quality of the reconstructed images is reduced by noise due to the reconstruction of images from random patterns. In this study, we improve the quality of CGI images using deep learning. A deep neural network is used to automatically learn the features of noise-contaminated CGI images. After training, the network is able to predict low-noise images from new noise-contaminated CGI images. (C) 2017 Elsevier B.V. All rights reserved.

copyright © 2016 Society of Information Display. All rights reserved. We proposed a volumetric display composed of photochromic materials. It can be controlled in a non-contact from the outside. In this study, the photochromic material was mixed into transparent silicone to be solid. We made a volumetric display that can display different multiple pictures depending on the surface to observe. The gradation expression is realized by overlapping the colored voxels in a row to the observed directions.

© 2018 International Display Workshops. All rights reserved. In previous studies, we improved an algorithm for designing a directional volumetric display and enable it to record any image. In this study, we confirmed that the improved algorithm can obtain images of equivalent quality to original algorithm using subjective evaluation. This suggests that the improved algorithm is more effective.

© 2018 International Display Workshops. All rights reserved. Our research group developed a directional volumetric display that exhibits images in multiple directions. However, the images exhibited from the display contain many noise. Therefore, we proposed an image quality improvement algorithm using deep learning and showed its effectiveness.

In this study, we describe the fabrication of a high-resolution directional volumetric display that can display multiple images in different directions. The display designs can be used to show animations using strings; however, improving the resolution of such displays is difficult. Previously, the arrangement of strings has only been determined experimentally, making fabrication of volumetric displays a challenge. The goal of the present study is to improve resolution using simulations and to determine the arrangement of strings under three constraints. This simplified the fabrication of a directional volumetric display with 345 strings, which can display two different 20×20  pixel images in two different directions. A large high-resolution directional volumetric display can be fabricated using the proposed method. The string-type display has high artistic potential and is expected to find applications in the amusement and entertainment fields.

We propose a deep-learning- based classification of data pages used in holographic memory. We numerically investigated the classification performance of a conventional multilayer perceptron (MLP) and a deep neural network, under the condition that reconstructed page data are contaminated by some noise and are randomly laterally shifted. When data pages are randomly laterally shifted, the MLP was found to have a classification accuracy of 93.02%, whereas the deep neural network was able to classify data pages at an accuracy of 99.98%. The accuracy of the deep neural network is 2 orders of magnitude better than the MLP. (C) 2017 Optical Society of America

We designed and developed a control circuit for a three-dimensional (3-D) light-emitting diode (LED) array to be used in volumetric displays exhibiting full-color dynamic 3-D images. The circuit was implemented on a field-programmable gate array; therefore, pulse-width modulation, which requires high-speed processing, could be operated in real time. We experimentally evaluated the developed system by measuring the luminance of an LED with varying input and confirmed that the system works appropriately. In addition, we demonstrated that the volumetric display exhibits different full-color dynamic two-dimensional images in two orthogonal directions. Each of the exhibited images could be obtained only from the prescribed viewpoint. Such directional characteristics of the system are beneficial for applications, including digital signage, security systems, art, and amusement. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.

We propose a holographic image restoration method using an autoencoder, which is an artificial neural network. Because holographic reconstructed images are often contaminated by direct light, conjugate light, and speckle noise, the discrimination of reconstructed images may be difficult. In this paper, we demonstrate the restoration of reconstructed images from holograms that record page data in holographic memory and quick response codes by using the proposed method. (C) 2017 Optical Society of America

In this study, a method to construct a full-colour volumetric display is presented using a commercially available inkjet printer. Photoreactive luminescence materials are minutely and automatically printed as the volume elements, and volumetric displays are constructed with high resolution using easy-to-fabricate means that exploit inkjet printing technologies. The results experimentally demonstrate the first prototype of an inkjet printing-based volumetric display composed of multiple layers of transparent films that yield a full-colour three-dimensional (3D) image. Moreover, we propose a design algorithm with 3D structures that provide multiple different 2D full-colour patterns when viewed from different directions and experimentally demonstrate prototypes. It is considered that these types of 3D volumetric structures and their fabrication methods based on widely deployed existing printing technologies can be utilised as novel information display devices and systems, including digital signage, media art, entertainment and security.

© 2017 Proceedings of the International Display Workshops. All rights reserved. Japanese students have a problem of low motivatbn for science courses. In order to solve this problem, we developed a simulator about the planets that works on the 2D display in previous study. In this study, help the stereoscopic recognition of students by operating the simulator in VR.

© 2017 Proceedings of the International Display Workshops. All rights reserved. A method to design "a 3D object containing multiple 2D infonnation patterns", which can exhibit different motion pictures to different directions, has been developed. However, it is difficult for humans to decide the placement of threads. In this study, we aim for realization of a simulator for a practical projection system to a directional volumetric display. The simulation results by our simulator was similar to the actual projection results. As a result, we confirmed that the simulator we developed is correct.

折りたたまれた平面から，二つの端点を引っ張るだけで強固な立体形状を形成する手法が本研究グループで開発されている．この技術を天体教育に応用し，教材を試作した．中学3年生の授業で使用したところ，良好な評価を得た．

This is the first study to demonstrate that colour transformations in the volume of a photochromic material (PM) are induced at the intersections of two control light channels, one controlling PM colouration and the other controlling decolouration. Thus, PM colouration is induced by position selectivity, and therefore, a dynamic volumetric display may be realised using these two control lights. Moreover, a mixture of multiple PM types with different absorption properties exhibits different colours depending on the control light spectrum. Particularly, the spectrum management of the control light allows colour-selective colouration besides position selectivity. Therefore, a PM-based, full-colour volumetric display is realised. We experimentally construct a mixture of two PM types and validate the operating principles of such a volumetric display system. Our system is constructed simply by mixing multiple PM types; therefore, the display hardware structure is extremely simple, and the minimum size of a volume element can be as small as the size of a molecule. Volumetric displays can provide natural three-dimensional (3D) perception; therefore, the potential uses of our system include high-definition 3D visualisation for medical applications, architectural design, human-computer interactions, advertising, and entertainment.

A three-dimensional (3D) structure designed by our proposed algorithm can simultaneously exhibit multiple two-dimensional patterns. The 3D structure provides multiple patterns having directional characteristics by distributing the effects of the artefacts. In this study, we proposed an iterative algorithm to improve the image quality of the exhibited patterns and have verified the effectiveness of the proposed algorithm using numerical simulations. Moreover, we fabricated different 3D glass structures (an octagonal prism, a cube and a sphere) using the proposed algorithm. All 3D structures exhibit four patterns, and different patterns can be observed depending on the viewing direction. (C) 2016 Optical Society of America

In this study, we propose and experimentally demonstrate a volumetric display system based on quantum dots (QDs) embedded in a polymer substrate. Unlike conventional volumetric displays, our system does not require electrical wiring; thus, the heretofore unavoidable issue of occlusion is resolved because irradiation by external light supplies the energy to the light-emitting voxels formed by the QDs. By exploiting the intrinsic attributes of the QDs, the system offers ultrahigh definition and a wide range of colours for volumetric displays. In this paper, we discuss the design, implementation and characterization of the proposed volumetric display's first prototype. We developed an 8 x 8 x 8 display comprising two types of QDs. This display provides multicolour three-type two-dimensional patterns when viewed from different angles. The QD-based volumetric display provides a new way to represent images and could be applied in leisure and advertising industries, among others.

We have developed an algorithm to record multiple two-dimensional information patterns in single volumetric display. In this technique, different two-dimensional information pattern is expressed by the observation position of the observer. We showed some application of this technique.

任意枚数の指向性画像を同時に表示する 3 次元オブジェクトの設計アルゴリズムについて述べる．本手法を用いて作製したオブジェクトは見る方向に応じて，異なる画像を表示する．従来技術では同時に表示できる画像の枚数や組み合わせに制限があったが，提案手法を用いることでこれらの制限を原理的に外すことが可能となった．CG によるシミュレーションと，レーザ加工を利用した試作によって本手法の有用性を示すことに成功した． また 3 種類のボリュームディスプレイに提案手法を実装することで，カラー化および動画化の実現可能性を示した．

ペーパークラフトとプロジェクションマッピングの技術を用いて，大型地球儀を製作する．投影対象を製作する際，ペーパークラフトの技術を用いることで球体を立体から平面に変換可能となり，平面にすることで可搬性が高まる．基礎研究として 20cm の球体をペーパークラフトで製作し，地球儀の映像を投影した．また，Kinectを用いることでジェスチャを検知し，地球儀が回転する映像を投影することができた．可搬性についても検証を行い，ペーパークラフトで製作した球体と実物の大型地球儀を比較し，ペーパークラフトで製作した球体の方が優れていることが確認できた．

3次元表示技術の一つに電子ホログラフィ技術がある.この電子ホログラフィでは,3次元の情報を記録したCGH (Computer Generated Hologram)が必要となる.しかしCGHの作成には膨大な量の計算を必要とするため,この分野の研究にとって大きな問題となっている.そこで我々はこの問題を解決するためにCGHを作成するためのWebアプリケーションを作成し,このアプリケーションを高速計算機に実装した.つまり,ネットワークに接続できる環境があれば,誰でも高速にCGHを作成できるシステムを構築した.Apache Tomcatを用いて高速計算機をサーバ化し,さらに,JSPやサーブレットを用いて表示画面やファイル操作の機能を実装した.また,CGHの作成にはCUDA (Compute Unified Device Architecture)を用いた既存の高速計算機を利用した.汎用計算機では20分以上かかる計算が,このシステムを用いることにより1秒以下で実現できる.

Diffraction calculations, such as the angular spectrum method and Fresnel diffractions, are used for calculating scalar light propagation. The calculations are used in wide-ranging optics fields: for example, Computer Generated Holograms (CGHs), digital holography, diffractive optical elements, microscopy, image encryption and decryption, three-dimensional analysis for optical devices and so on. However, increasing demands made by large-scale diffraction calculations have rendered the computational power of recent computers insufficient. We have already developed a numerical library for diffraction calculations using a Graphic Processing Unit (GPU), which was named the GWO library. However, this GWO library is not user-friendly, since it is based on C language and was also run only on a GPU. In this paper, we develop a new C++ class library for diffraction and CGH calculations, which is referred to as a CWO++ library, running on a CPU and GPU. We also describe the structure, performance, and usage examples of the CWO++ library. Program summary Program title: CWO++ Catalogue identifier: AELL_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AELL_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 109 809 No. of bytes in distributed program, including test data, etc.: 4 181 911 Distribution format: tar.gz Programming language: C++ Computer: General computers and general computers with NVIDIA GPUs Operating system: Windows XP, Vista, 7 Has the code been vectorized or parallelized?: Yes. 1 core processor used in CPU and many cores in GPU. RAM: 256 M bytes Classification: 18 External routines: CImg, FFTW Nature of problem: The CWO++ library provides diffraction calculations which are useful for Computer Generated Holograms (CGHs), digital holography, diffractive optical elements, microscopy, image encryption and decryption and three-dimensional analysis for optical devices. Solution method: FFT-based diffraction calculations, computer generated holograms by direct integration. Running time: The sample runs provided take approximately 5 minutes for the C++ version and 5 seconds for the C++ with GPUs version. (c) 2012 Elsevier B.V. All rights reserved.