Takahiro Okabe

Kyushu Institute of Technology

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Yoichi Sato

Japan Aerospace Exploration Agency

Imari Sato

National Institute of Informatics

Minoru Nagata

Vehicle Control Technologies (United States)

Yusuke Sugano

The University of Tokyo

Masataka Kato

Fukui Red Cross Hospital

M. Nagata

National Agriculture and Food Research Organization

Shigenao Maruyama

Tohoku University

Minori Shirota

Hirosaki University

Yoichi Sato

The University of Tokyo

Akihiro Sugimoto

National Institute of Informatics

Cooperative Institutions

The University of Tokyo

High Energy Accelerator Research Organization

Campbell Collaboration

Tohoku University

Nagoya University

Hitachi (Japan)

University of the Basque Country

Princeton University

Osaka University

University of Cincinnati

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Auto-Radiometric Calibration in Photometric Stereo

IEICE Transactions on Information and Systems (2016)

Wiennat Mongkulmann Takahiro Okabe Yoichi Sato

We propose a framework to perform auto-radiometric calibration in photometric stereo methods to estimate surface orientations of an object from a sequence of images taken using a radiometrically uncalibrated camera under varying illumination conditions. Our proposed framework allows the simultaneous estimation of surface normals and radiometric responses, and as a result can avoid cumbersome and time-consuming radiometric calibration. The key idea of our framework is to use the consistency between the irradiance values converted from pixel values by using the inverse response function and those computed from the surface normals. Consequently, a linear optimization problem is formulated to estimate the surface normals and the response function simultaneously. Finally, experiments on both synthetic and real images demonstrate that our framework enables photometric stereo methods to accurately estimate surface normals even when the images are captured using cameras with unknown and nonlinear response functions.

Photometric Stereo

Radiometric Calibration

10.1587/transinf.2016edp7150

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Citations (1)

Radiation Effects of Double Layer Dielectric Films

IEEE Transactions on Nuclear Science (1986)

Kikuo Watanabe Masataka Kato Takahiro Okabe Minoru Nagata

Double layer dielectric films are examined for Si surface passivation in a radiation hardened Si device. The double layer dielectric films of Si3N4/SiO2 and PSG/SiO2 are shown to have lower sensitivity to ionizing radiation than a CVD-SiO2/SiO2 film named a double layer SiO2 film. However, the former two dielectric films show much larger initial interface state densities than the latter one. Effects of post oxidation annealing on the radiation induced interface states are also studied. The double layer SiO2 film is applied to realize an IIL device with a radiation tolerance of more than one Mrad(Si).

Passivation

Double layer (biology)

10.1109/tns.1986.4334581

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Citations (35)

Stacked I2L circuit

Electronics Letters (1976)

Kenji Kaneko Takahiro Okabe M. Nagata

A new integrated-injection-logic circuit which consists of multiple (m) layers of I2L circuit blocks and operates with an extremely low power dissipation is discussed. The same logic function is realised with m-times less power than a conventional I2L circuit.

10.1049/el:19760192

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Citations (2)

OpenFOAMを用いた水平対流場の三次元伝熱解析による熱流動場の時空間発展の評価

The Proceedings of the Thermal Engineering Conference (2023)

Shoei Yamada Kyosuke Ando Takahiro Okabe Takuma Kogawa

10.1299/jsmeted.2023.b224

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Hierarchical Gaussian Descriptors with Application to Person Re-Identification

arXiv (Cornell University) (2017)

Tetsu Matsukawa Takahiro Okabe Einoshin Suzuki Yoichi Sato

Describing the color and textural information of a person image is one of the most crucial aspects of person re-identification (re-id). In this paper, we present novel meta-descriptors based on a hierarchical distribution of pixel features. Although hierarchical covariance descriptors have been successfully applied to image classification, the mean information of pixel features, which is absent from the covariance, tends to be the major discriminative information for person re-id. To solve this problem, we describe a local region in an image via hierarchical Gaussian distribution in which both means and covariances are included in their parameters. More specifically, the region is modeled as a set of multiple Gaussian distributions in which each Gaussian represents the appearance of a local patch. The characteristics of the set of Gaussians are again described by another Gaussian distribution. In both steps, we embed the parameters of the Gaussian into a point of Symmetric Positive Definite (SPD) matrix manifold. By changing the way to handle mean information in this embedding, we develop two hierarchical Gaussian descriptors. Additionally, we develop feature norm normalization methods with the ability to alleviate the biased trends that exist on the descriptors. The experimental results conducted on five public datasets indicate that the proposed descriptors achieve remarkably high performance on person re-id.

Discriminative model

Normalization

Feature (linguistics)

10.48550/arxiv.1706.04318

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Numerical simulation of suppression of biological reaction using ice slurry

The Proceedings of the Thermal Engineering Conference (2019)

Haruki Nishikawa Takahiro Okabe Taimei MIYAGAWA Koji Fumoto

In this study, we investigated the effect of rapid cooling using ice slurry on the metabolic activity of biological tissue by a numerical simulation. In this study, we simulated the melting heat transfer of ice slurries being placed on the biological tissue. We examined the optimum cooling method by changing the IPF (ice packing factor) and amount of ice slurry. As a result, rapid cooling using ice slurry is effective in preventing ischemic damage due to ischemia during surgery, and it suggested that there is a thermally optimal amount of ice slurry and IPF depending on the purpose.

Ice water

Biological tissue

10.1299/jsmeted.2019.0159

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Manifold-based photometric stereo with cast shadows (コンピュータビジョンとイメージメディア)

情報処理学会研究報告コンピュータビジョンとイメージメディア（CVIM） (2008)

Lulu Chen Imari Sato Takahiro Okabe Yoichi Sato

Photometric Stereo

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Joint Estimation of Illumination Distribution and Response Function from Shadows

IEICE Technical Report; IEICE Tech. Rep. (2020)

Takuto Nakashima Ryo Matsuoka Takahiro Okabe

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High performance network with merged optical and IP

Yamano Satoru Takahiro Okabe Yutaka Oshima Katsuhiko Sato T. Kanoh

The ubiquitous network is, in a sense, the ultimate goal of communication services. As the desire for ubiquitous network becomes increasingly clear, network service providers are anticipated to develop a high performance network infrastructure for providing larger capacity and more flexible communication services. If such a communication infrastructure can be constructed inexpensively while retaining scalability, it should present a new business opportunity for network service providers. This paper presents a new network infrastructure that merges optics with IP, and then studies how to realize the infrastructure and what the component technologies are. In addition, this paper takes a look at the network elements that comprise an optical-IP merged network and services.

Network service

IP Multimedia Subsystem

10.1109/hpsr.2002.1024222

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Citations (2)

Manifold-Based Photometric Stereo with Cast Shadows

IEICE Technical Report; IEICE Tech. Rep. (2008)

Lulu Chen Takahiro Okabe Imari Sato Yoichi Sato

Photometric Stereo

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