研究者詳細 - 赤木　康宏

論文 - 赤木　康宏

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Detection of Localization Failures Using Markov Random Fields With Fully Connected Latent Variables for Safe LiDAR-Based Automated Driving

Akai, N; Akagi, Y; Hirayama, T; Morikawa, T; Murase, H

IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS 23 巻 ( 10 ) 頁： 17130 - 17142 2022年10月

出版者・発行元：IEEE Transactions on Intelligent Transportation Systems

Most of the recent automated driving systems assume the accurate functioning of localization. Unanticipated errors cause localization failures and result in failures in automated driving. An exact localization failure detection is necessary to ensure safety in automated driving; however, detection of the localization failures is challenging because sensor measurement is assumed to be independent of each other in the localization process. Owing to the assumption, the entire relation of the sensor measurement is ignored. Consequently, it is difficult to recognize the misalignment between the sensor measurement and the map when partial sensor measurement overlaps with the map. This paper proposes a method for the detection of localization failures using Markov random fields with fully connected latent variables. The full connection enables to take the entire relation into account and contributes to the exact misalignment recognition. Additionally, this paper presents localization failure probability calculation and efficient distance field representation methods. We evaluate the proposed method using two types of datasets. The first dataset is the SemanticKITTI dataset, whereby four methods are compared with the proposed method. The comparison results reveal that the proposed method achieves the most accurate failure detection. The second dataset is created based on log data acquired from the demonstrations that we conducted in Japanese public roads. The dataset includes several localization failure scenes. We apply the failure detection methods to the dataset and confirm that the proposed method achieves exact and immediate failure detection.

DOI： 10.1109/TITS.2022.3164397

Web of Science

Scopus

Driving behavior modeling based on hidden markov models with driver's eye-gaze measurement and ego-vehicle localization

Akai N.

IEEE Intelligent Vehicles Symposium, Proceedings 2019-June 巻頁： 949 - 956 2019年6月

Simultaneous description of logical design and implementation of automated driving systems

Akagi Y.

IEEE Intelligent Vehicles Symposium, Proceedings 2019-June 巻頁： 1565 - 1570 2019年6月

自己回帰入出力隠れマルコフモデルを用いた運転行動のモデル化

赤井直紀, 平山高嗣, モラレスルイス洋一, 赤木康宏, 劉海龍, 村瀬洋

ロボティクス・メカトロニクス講演会講演概要集 2019 巻 ( 0 ) 頁： 2A1-E05 - E05 2019年

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

This paper presents a driving behavior modeling method using autoregressive input-output hidden Markov models (AIOHMMs). First, model parameter learning and discrimination ways using the AIOHMMs are detailed. In experiments, we model four driving maneuvers with driver's eye-gaze and ego-vehicle localization information and compare maneuver discrimination performances by four types of HMMs. Additionally, we discuss modeling performance by the AIOHMMs through the experiments.

DOI： 10.1299/jsmermd.2019.2a1-e05

CiNii Research

A Risk-index based Sampling Method to Generate Scenarios for the Evaluation of Automated Driving Vehicle Safety 査読有り

Y. Akagi, R. Kato, S. Kitajima, J. Antona-Makoshi and N. Uchida

IEEE Intelligent Transportation Systems Conference (ITSC) 頁： 667 - 672 2019年

自転車の他者追い越し場面における移動予測に基づく自動減速制御システムに関する研究査読有り

江澤和浩, ポンサトーンラクシンチャラーンサク, 赤木康宏, 前田健太, 児島隆生

日本機械学会論文集 84 巻 ( 865 ) 頁： 17-00557-17-00557 2018年

記述言語：日本語掲載種別：研究論文（学術雑誌）

This paper presents motion prediction model of cyclist based on potential field for a hazard-anticipatory collision avoidance braking system to enhance the collision avoidance performance and secure the smoothness of driving. The target situation is chosen as the scene that a cyclist overtakes a pedestrian or another slowcyclist based on the traffic survey. The 1st order motion predictionmethod reaches its limit under the situation that a cyclist runs towards a pedestrian or another cyclist as the prediction is conducted based on the current position and velocity of cyclist within a finite time horizon. If the overtake action of cyclist can be predicted before the cyclist changes moving direction, the vehicle maneuver to avoid collision with cyclist can be executed in advance without activating harsh braking. The trajectories of cyclists overtakes a pedestrian and a slower cyclist is measured to find the characteristics in overtake action.Motion prediction model of cyclist based on potential field is constructed by considering the trajectory analysis. The effectiveness of the proposed prediction model in the target scenario is verified by comparing the measured trajectory with the calculated data based on 1st order prediction and the proposed method.

道路領域検出と画像レジストレーションに基づく自車両位置推定査読有り

風間恵介, 川勝俊輝, 赤木康宏, 毛利宏

日本機械学会論文集 83 巻 ( 849 ) 頁： 17-00014-17-00014 2017年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本機械学会

This paper describes the development of a new localization method using a simple 2D map. The general method for localization using a 2D map is to match between the boundary line on the 2D map and the detected boundaries in the real world, i.e. lane markers, walls of building, or curbs. It is necessary to create a differential process in order to detect boundary lines of the road. If these methods try to detect small changes, the false-detection rate increases due to enhanced noises; if they try to reduce the effect of noise, boundary lines are misdetected. The estimation result of this method deteriorates drastically if the false-detection or misdetection of the boundary line occurs. We propose the new localization method based on the road area detection. First, the road map is extracted from the boundary lines on a 2D map. Next, the road plane image is made by the road area detected using LiDAR in the real world. Finally, the road map and the road plane image are matched by image registration. We confirmed that the proposed method have accurate estimation performance with several noise and low-cost calculation from the simulation. And we conducted the performance validation of proposed method in the real world. As a result, we confirmed the same tendency as simulation results.

DOI： 10.1299/transjsme.17-00014

先読み運転支援を可能にするための逆衝突確率モデルを用いた経路計画手法に関する研究査読有り

赤木康宏, ラクシンチャラーンサク, ポンサトーン

自動車技術会論文集 48 巻 ( 4 ) 頁： 859-865 - 865 2017年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：自動車技術会

本研究では運転支援システムに用いる経路計画手法を提案する．交通参加者の周辺を走行する際の安全性を評価するために，逆衝突確率モデルとよぶモデルを構築することで，複数の交通参加者が存在する環境に対して効率的に経路を生成する．評価実験として，提案手法が生成する経路と実路の走行データの比較を行う．

CiNii Books

Ontology based collection and analysis of traffic event data for developing intelligent vehicles 査読有り

Akagi Yasuhiro

2017 IEEE 6TH GLOBAL CONFERENCE ON CONSUMER ELECTRONICS (GCCE) 頁： . 2017年

Fundamental Study on Road Detection Method Using Multi-Layered Distance Data with HOG and SVM 査読有り

Kazama Keisuke, Akagi Yasuhiro, Raksincharoensak Pongsathorn, Mouri Hiroshi

JOURNAL OF ROBOTICS AND MECHATRONICS 28 巻 ( 6 ) 頁： 870-877 2016年12月

点と線と面のランドマークによる道に迷いにくいナビゲーション・システムとその評価査読有り

森永寛紀, 若宮翔子, 谷山友規, 赤木康宏, 小野智司, 河合由起子, 川崎洋

情報処理学会論文誌 57 巻 ( 4 ) 頁： 1227-1238 2016年4月

記述言語：日本語掲載種別：研究論文（学術雑誌）

自動車に限らず，二輪車や歩行による移動時に，スマートフォンなど携帯端末によるルート・ナビゲーション・システムを利用するユーザが増加している．しかし，二輪車による移動や歩行中に小さな画面で経路を確認することは危険をともなうほか，音声などによる案内も難しい．その解決方法として，経路や自己位置をなるべく確認しないですむように，人が記憶しやすく視認性の高いランドマークを用いたナビゲーション・システムが提案されている．それらのシステムで主に用いられているランドマークは，1)近くまで行かなければ視認できないが，ユーザの現在位置を高精度で同定できる，局所的（点の）ランドマーク（郵便局やコンビニエンスストアなど）か，2)遠方からでも視認できるが，現在位置をおおまかにしか同定できない，広域的（面の）ランドマーク（電波塔や高層ビルなど）の2種類であった．この2種類のランドマークは，その性質の違いから同時に使用することが難しく，これまでのシステムではいずれか一方を用いていた．そこで，我々は，3)すぐ近くまで行かなければ視認できないが，その範囲が線状に広がりを持つもの（電車通りや河川など）を線のランドマークとして定義し，従来困難であった複数種類のランドマークの同時使用を実現する．これにより，従来のナビゲーション・システム（最短経路やGoogle Directions）に比べ，現在位置や案内地図の参照回数を減らすことや，目的地まで短い時間で到達可能な経路を探索することができ，GPSが利用できない状況においても道に迷いにくいナビゲーションを実現した．さらに，提案手法の有効性を確認するために，仮想空間でのGoogle Street Viewを用いた移動と現地での実空間移動による評価を行い，一定の効果を確認した．Recently, the number of people who use navigation systems with mobile devices on the streets is rapidly increasing. As the increase of the number of the user of these systems, concerns on safety is arisen because it makes people to frequently reconfirm the route on small screens of mobile devices. Therefore, navigation systems using highly visible and recognizable landmarks have been proposed. The landmarks are 1) buildings that can help users identify own location accurately but cannot be recognized from far (local landmarks) and 2) tall buildings that are highly visible from a long distance but give users only rough information (global landmarks). In this paper, we define three types of landmarks according to their properties, "point landmarks" for the above 1), "area landmarks" for the above 2), and "linear landmarks" which are not visible from far but users can easily follow along. We propose a navigation system to generate route directions by exploiting several types of landmarks at the same time, which is difficult by other conventional methods. In the experiment, we tested the system with both virtural and real environments and confirmed that users of our system could reach the destination using a small number of landmarks, which means users need to check screens less than other systems.

Longitudinal and Lateral Motion Planning Method for Avoidance of Multi-Obstacles in Urban Environments Based on Inverse Collision Probability 査読有り

Akagi Yasuhiro, Raksincharoensak Pongsathorn

2016 IEEE INTELLIGENT VEHICLES SYMPOSIUM (IV) 頁： 827-832 2016年

Stochastic Driver Speed Control Behavior Modeling in Urban Inter-sections Using Risk Potential-Based Motion Planning Framework 査読有り

Akagi Yasuhiro, Raksincharoensak Pongsathorn

2015 IEEE INTELLIGENT VEHICLES SYMPOSIUM (IV) 頁： 368-373 2015年

An Analysis of an elderly driver behaviour in Urban Intersections based on a Risk Potential Model 査読有り

Akagi Yasuhiro, Raksincharoensak Pongsathorn

IECON 2015 - 41ST ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY 頁： 1627-1632 2015年

簡易な3次元ビデオ計測システムとWebベースのデータ共有サービスによる効率的な教育コンテンツ作成支援(<特集>教育・訓練・支援) 査読有り

森永寛紀, 牛之濱宅哉, 木村亮介, 赤木康宏, 三鴨道弘, 小野智司, 山之上卓, 川崎洋

VR学会論文誌 20 巻 ( 4 ) 頁： 311-321 2015年

記述言語：日本語掲載種別：研究論文（学術雑誌）

In this paper, we present an interactive 3D animation creation system that enables the user to capture, edit the moving objects and share them easily on the web. Recently, educational concept called active leaning has been becoming important in the field of education. The difference between the active leaning and usual education is that the learner actively absorbs the educational information not only from the lecturer, but also from other media contents such as videos and images. Therefore, various kinds of media contents aiming for active learning are required to help the learners. As the one of such media contents, we developed a system that can create 3D video data and share them on a web service. Concretely, in our system, the 3D contents are acquired by using Kinects on a graphical user interface. By using the proposed system, the user can edit and integrate the other contents such as music and images easily. The contents can be uploaded on the web server that provides the experience to manipulate the 3D animation intuitively through a touch interface. In this paper, we explain the overview of the proposed system and the details of the our algorithms to reconstruct 3D data. The experiment shows our system can obtain the 3D data efficiently by using a novel approach. As the conclusion, we show some demos to validate that the system is available for educational use and a user can operate the proposed system efficiently.

運転行動解析のための点群位置合わせに基づく走行軌跡の復元に関する研究査読有り

赤木康宏, ラクシンチャラーンサクポンサトーン

精密工学会誌 81 巻 ( 12 ) 頁： 1113-1118 2015年

記述言語：日本語掲載種別：研究論文（学術雑誌）

Advanced driving assistance systems (ADAS) for various driving scenarios are developed. To develop and to evaluate the ADAS, a large quantity and high quality database of actual driving data is needed. In this paper, we propose a driving trajectory estimation method based on a 3D point cloud. The registration methods of the point cloud (e.g. ICP) has advantages in the accuracy of the estimation of the local (short range) motion. However, since the registration methods estimate the relative motions of frame by frame, estimation errors are accumulated and it is difficult to apply the method for long distance analysis. To solve this problem, a global trajectory correction method based on GNSS information. The evaluations of the proposed system are performed by using the actual driving data in an urban road.

Exemplar-Based Hole-Filling Technique for Multiple Dynamic Objects 査読有り

Pagliardini Matteo, Akagi Yasuhiro, Slomp Marcos, Furukawa Ryo, Sagawa Ryusuke, Kawasaki Hiroshi

IMAGE AND VIDEO TECHNOLOGY, PSIVT 2013 8333 巻頁： 242-253 2014年

顔の部位識別に基づくマーカレスモーションキャプチャに関する研究査読有り

赤木康宏, 古川亮, 佐川立昌, 小川原光一, 川崎洋

精密工学会誌 79 巻 ( 11 ) 頁： 1152-1158 2013年

記述言語：日本語掲載種別：研究論文（学術雑誌）

In this paper, we propose a marker-less motion capture method for a human face. We detect the movement of a face as the deformation from the initial pose to other poses. In such cases, the non-rigid registration algorithms are commonly used to detect the movement of an object. However, since the features of the movement of a face vary in each facial part, it complicates the registration problem. In our method, we recognize the facial parts by using Random Forest algorithm to be simplified to solve the registration problem. Then, we classify the facial parts into five types : nose, mouth, eye, cheek and obstacle. And we define the feature vector of each point of the face by using Fast Point Feature Histograms and a normalized position. We train the Random Forest based on the feature vector to recognize the facial parts from an arbitrary point set data. After the recognition of the facial parts, we detect the movement of the each part by using a non-rigid registration algorithm. Finally, we combine the translations of the each point as the deformation of the face by using the deformation technique based on a Radial Basis Function. In our results, we show that the proposed method enable us to detect the motion of the face more accurately.

DEMO PAPER: A CONTENT CREATION SYSTEM FOR INTERACTIVE 3D ANIMATIONS 査読有り

Akagi Yasuhiro, Furukawa Masayuki, Fukumoto Shinya, Kawai Yukiko, Kawasaki Hiroshi

ELECTRONIC PROCEEDINGS OF THE 2013 IEEE INTERNATIONAL CONFERENCE ON MULTIMEDIA AND EXPO WORKSHOPS (ICMEW) 頁： . 2013年

INTERACTIVE 3D ANIMATION SYSTEM BASED ON TOUCH INTERFACE AND EFFICIENT CREATION TOOLS 査読有り

Akagi Yasuhiro, Furukawa Masayuki, Fukumoto Shinya, Kawai Yukiko, Kawasaki Hiroshi

2013 IEEE INTERNATIONAL CONFERENCE ON MULTIMEDIA AND EXPO (ICME 2013) 頁： . 2013年

A facial motion tracking and transfer method based on a key point detection 査読有り

Akagi Yasuhiro, Furukawa Ryo, Sagawa Ryusuke, Ogawara Koichi, Kawasaki Hiroshi

WSCG 2013, COMMUNICATION PAPERS PROCEEDINGS 頁： 137-144 2013年

A Study on the Animations of Swaying and Breaking Trees based on a Particle-based Simulation 査読有り

Y.Akagi, K. Kitajima

Journal of WSCG 20 巻 ( 1 ) 頁： 21 - 27 2012年6月

GFFD空間変形手法に基づくカメラ画像からの簡易足型モデリング査読有り

近藤聡, 赤木康宏, 北嶋克寛

精密工学会誌 76 巻 ( 4 ) 頁： 474-480 2010年

掲載種別：研究論文（学術雑誌）

This paper proposes a novel method of generating a 3D virtual foot model from multiple camera image data based on the GFFD deformation method. 3D virtual foot models for individual persons can be generated easily and rapidly with considerably low cost. By estimating the cause of errors that can occur in the whole process and endeavoring to lower the errors, we succeeded to achieve satisfactory accuracy. The errors are mainly classified into two kinds. One occurs in transforming process with use of the GFFD deformation method and the other in obtaining 3D coordinates of feature points. So, we devoted ourselves to eliminate the cause of both errors and repeated experiments again and again. As a result, we got to get a 3D virtual foot model within acceptable error range. The average error is 1.32&sim;1.72mm.

並列処理を用いた樹木アニメーション制作支援システムに関する研究査読有り

赤木康宏, 北嶋克寛

精密工学会誌 75 巻 ( 7 ) 頁： 859-864 2009年

掲載種別：研究論文（学術雑誌）

In this paper, we propose a parallel processing technique for creating animation of swaying trees in the wind based on physical simulation. Our technique independently assigns each tree to computation nodes. The each node processes not only parallel rendering for tree shapes, but also parallel simulation of the wind and bending of branches. This independency reduces data traffics between nodes and realizes efficient parallel processing. When the each node independently simulates the wind, it is necessary to consider wind interactions between the upper and the lower side tree. Therefore, we realize cooperative wind simulation with independent cluster nodes, by inventing a novel method for estimates of wind velocity of lower-side trees from simulation results of upper-side trees. By synthesizing rendered images from each cluster, our system generates animations of swaying trees. Through many experiments using these techniques, it is shown that the efficiency of parallel processing for animation of swaying trees is verified.

GFFDに基づく顔形状モデリングに関する研究査読有り

北嶋克寛, 赤木康宏, 山内玲, 岡澤直輝, 樋口靖和

精密工学会誌 74 巻 ( 8 ) 頁： 883-890 2008年8月

記述言語：日本語掲載種別：研究論文（学術雑誌）

In this paper, we propose a method of generating individual facial models based on a generic facial model with not only a skin model but also additional data such as skull model, facial expression muscle model, etc. When the generic facial model is transformed into individual facial models by GFFD (Generalized Free-Form Deformation), not only skin model but also additional data are automatically altered into a suitable state for individual faces at the same time. By using this method, we can easily do a simulation of facial expression or hairstyle without making additional data for each individual facial model.

背景画における陰影付け技法に基づくアニメ制作のための樹木の色域別レンダリング査読有り

赤木康宏, 片塰満則, 北嶋克寛

情報処理学会論文誌 49 巻 ( 3 ) 頁： 1489-1499 2008年3月

記述言語：日本語掲載種別：研究論文（学術雑誌）

本研究では，アニメ制作に用いる，背景画と呼ばれる絵画における樹木の陰影付け技法に着目し，任意の作風を持つ背景画を生成することのできるNon-Photorealistic Rendering 手法を提案する．アニメ制作では，背景画と呼ばれる風景などを描いた1 枚の絵画に対して，登場人物などの動きを表現する複数のレイヤを合成することで1 つのシーンを構成する方法が一般に用いられる．背景画は作品の印象を決定づける重要な要素であるが，樹木を含む自然景観が背景となる作品の制作過程においては，扱う対象の量や形状の複雑さなどから，すべてを人手で行えば膨大な作業を必要とする．本論文では，絵筆により樹木を描画する際の手順を分析し，葉の配色および陰影付けが画家固有の作風を決定する主要な要因の1 つであることを示し，CG で用いられる樹木モデルの持つ様々な情報（葉の位置および法線，枝の接続関係，枝につく葉の集団の重心など）に基づき，各色の占める領域を容易に制御できる新たな手法を提案する．これにより任意の作風を持つ背景画を生成することが容易になる．色域の制御に関しては，背景画において広く用いられる，詳細形状の簡略化，空気遠近法などの描画技法に基づき，5 種類の制御関数を提案する．著者らが開発した写実的な「風に揺れる樹木のアニメーション生成システム1) 2)」に本手法を適用し，豊かな動きを持つ背景画の自動生成を可能にした実例を示す．最後に，本手法に基づくアニメーション生成を行い，任意の作風を持った映像の生成が可能であることを比較実験などにより検証する．In this paper, we describe a non-photorealistic rendering (NPR) framework for generating background art in animation. The background art, in many cases that is a Landscape Painting, is generally used in animation productions. One background art and multiple layers of moving characters compose a scene. The background art is one of most important factor for making the impression of an animation. We propose, in particular, a NPR technique that can reproduce painting techniques characteristic of background art such as leaf painting based on just a few colors, shading to produce a spherical effect, and aerial perspective. This technique can generate dynamic background art having a swaying motion in the wind by applying the animation generation tool for swaying trees developed by the authors 1),2) The proposed method, in contrast, is based on a painting technique for background art, which enables it to pick up features of the target work of art and to reproduce its style.

Study on a method of generating a 3D virtual foot model with use of a measuring technique based on multiple camera image data 査読有り

Kondo Satoshi, Akagi Yasuhiro, Kitajima Katsuhiro

PROCEEDINGS OF SICE ANNUAL CONFERENCE, VOLS 1-8 頁： 7-11 2007年

統計的手法に基づく種の特徴を保持する樹木形状の生成手法に関する研究査読有り

赤木康宏, 北嶋克寛

電子情報通信学会論文誌. D, 情報・システム = The IEICE transactions on information and systems (Japanese edition) 89 巻 ( 5 ) 頁： 1019-1035 2006年5月

記述言語：日本語掲載種別：研究論文（学術雑誌）

本研究は,三次元コンピュータグラフィックスにおける樹木形状の生成において,統計学に基づく分析手法により樹木形状を自動的に分析し,種の特徴と自然な多様性を兼ね備えた樹木形状を自動生成するための手法を提案している.樹木は自然景観や街並みなど,様々なシーンに用いられる重要なオブジェクトの一つであり,これまで数多くの形状生成に関する研究が行われている.多数の樹木を用いるシーンでは,同じ種の樹木をそれぞれの形状が異なるように生成する必要がある.そのため,これまでの樹木形状生成に関する研究では,対象とする樹木の特徴に合わせた形状生成アルゴリズムを考案し,乱数や生長シミュレーションなどによって多様性を表現することがほとんどであった.しかし,種の特徴をとらえた形状生成を行う際には,対象となる樹木について詳しく調査する必要があるので多くの作業を要し,また一般の利用者が生成システムに対して新たな種を追加することは困難であるという問題がある.本論文は,写真情報から得た樹木形状データを統計学に基づいて分析し,種の特徴と多様性を表現する樹木モデルを構築し,それに基づいて大量の樹木の自動生成を行うことを可能にする一連の手法を提案する.それらは,(1)統計学による分析を行うことを目的とした,様々な樹木の形状を包括的に扱うことのできる共通のデータ構造による表現手法,(2)統計学に基づく分析手法により樹木データを分析し,樹木パラメータの相互関係と値の分布を数理モデルで表現する手法,(3)分析に用いる樹木形状データを収集する手間を軽減することを目的とした,写真からの立体復元手法を用いた樹木パラメータの取得手法,からなる.以上の3手法を用いて,種の特徴に従う樹木形状の自動生成を実現する.最後に,一連の手法の有効性を検証するために,樹木形状の生成実験を行い,実際の樹木と比較することにより,種の特徴と自然な多様性をもつ樹木形状を自動生成することが可能であることを示す.

物理シミュレーションに基づく風に揺れる樹木のアニメーション査読有り

赤木康宏, 佐波晶, 北嶋克寛

情報処理学会論文誌 46 巻 ( 7 ) 頁： 1797-1809 2005年7月

記述言語：日本語掲載種別：研究論文（学術雑誌）

本研究は，景観シミュレーションなどで用いられる樹木のCGモデルを用い，樹形や葉の大きさの違いによる気流の変化を考慮した風に揺れる樹木のアニメーションを生成するための手法を提案している．複雑な形状を持つ樹木周辺の風のシミュレーションを行うためには，枝や葉などの風を遮る物体が風に及ぼす影響を考慮する必要がある．風の物理シミュレーションモデルにおいて非圧縮性流体におけるNavier-Stokesの方程式を用いると，一般に次のような問題が生じる．樹木形状の詳細な形状までを考慮すると，計算量が増大しリアルタイムのアニメーション生成が困難になる，という問題である．そこで，本論文では，枝や葉のように類似した形状を持ちかつ樹木全体に数多く存在するパーツを風速を減少させる単純な抵抗体としてモデル化し，抵抗体の空間分布を表す境界条件マップを樹木モデルから自動生成することにより，計算量を減らしリアルタイム性のあるアニメーション生成を可能にする新たな手法を提案している．また，本手法は，空間全体の風の動きに階層的な計算手法を適用することにより，樹木周囲の自然な風の流れや樹木どうしの影響などについても高速に計算することができるという特長を持つ．これらの特長に関する各種実験結果を示し，複雑なパーツ形状からなる樹木が風に揺れる様子のアニメーションを力学的な根拠に基づきかつ高速に自動生成できことを実証した．This paper presents a series of techniques for generating animations of trees swaying in the wind, in consideration of the influences that the tree shapes and leaf sizes give to the air current. To do the simulation of the wind around a tree having a complicated shape, it is necessary to consider the influence that some objects obstructing the wind such as leaves or branches give. Generally, the following problem occurs when we use the incompressible Navier-Stokes equations in a physical simulation model of the wind. Computational complexity increases because of considering the details of tree shapes, so it is difficult to generate the animations in real-time. Therefore, this paper proposes a novel method that reduces the computational complexity and realizes an animation in real-time, by means of a boundary condition map expressing space distribution of resistances from tree models automatically. In this case, we make a model as simple resistances decreasing the wind velocity from the parts that have similar shapes like leaves and branches. And also, it has another advantage that the influences between a tree and others can be rapidly calculated by using a hierarchical calculation method. Finally, through many experiments using these methods, it is shown that real-time animations of swaying trees in the wind can be realized.

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