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論文

Image selection method from image sequence to improve computational efficiency of 3D reconstruction; Application of fixed threshold to remove redundant images

羽成 敏秀; 中村 啓太*; 今渕 貴志; 川端 邦明

Journal of Robotics and Mechatronics, 36(6), p.1537 - 1549, 2024/12

本稿では、時系列画像から3次元モデルを効率的に生成するための画像選択法を導入した立体復元処理について述べる。効率的な立体復元に適した画像を得るために、時系列画像中の冗長画像を除去する画像選択法の適用を試みた。提案手法では、オプティカルフローと固定しきい値に基づいて、時系列画像から適切な画像を選択する。その結果、提案手法により、カメラで取得した時系列画像に基づく立体復元処理の計算量を削減することができた。その結果、立体復元精度を一定に保ったまま、立体復元処理の計算量を削減できることを確認した。

論文

A Study on the effects of photogrammetry by the camera angle of view using computer simulation

中村 啓太; 羽成 敏秀; 松本 拓; 川端 邦明; 八代 大*

Journal of Robotics and Mechatronics, 36(1), p.115 - 124, 2024/02

During the decommissioning activities, a movie was shot inside the reactor building during the investigation of the primary containment vessel by applying photogrammetry, which is one of the methods for three-dimensional (3D) reconstruction from images, to the images from this movie, it is feasible to perform 3D reconstruction of the environment around the primary containment vessel. However, the images from this movie may not be suitable for 3D reconstruction because they were shot remotely by robots owing to limited illumination, high-dose environments, etc. Moreover, photogrammetry has the disadvantage of easily changing 3D reconstruction results by simply changing the shooting conditions. Therefore, this study investigated the accuracy of the 3D reconstruction results obtained by photogrammetry with changes in the camera angle of view under shooting conditions. In particular, we adopted 3D computer graphics software to simulate shooting target objects for 3D reconstruction in a dark environment while illuminating them with light for application in decommissioning activities. The experimental results obtained by applying artificial images generated by simulation to the photogrammetry method showed that more accurate 3D reconstruction results can be obtained when the camera angle of view is neither too wide nor too narrow when the target objects are shot and surrounded. However, the results showed that the accuracy of the obtained results is low during linear trajectory shooting when the camera angle of view is wide.

論文

Three-dimensional visualization of a beta-emitting nuclide by combining a directional Geiger-Mueller counter and Structure from Motion

佐藤 優樹; 峯本 浩二郎*; 根本 誠*

Journal of Instrumentation (Internet), 16(10), p.C10008_1 - C10008_8, 2021/10

 被引用回数:4 パーセンタイル:28.05(Instruments & Instrumentation)

At the Fukushima Daiichi Nuclear Power Station (FDNPS) where the accident occurred due to large tsunami caused by the Great East Japan Earthquake of 11 March 2011, it is important to understand and visualize the distribution of radioactive substances in order to reduce exposure doses of workers and to establish decontamination plans. We focused on the importance of visualizing beta-emitting nuclides in addition to gamma-emitting ones to reduce the exposure dose of workers at the FDNPS, and proposed a method for three-dimensional (3-D) visualizing the position of beta-emitting ones. By combining directional Geiger-Mueller counter with Structure from Motion technology using a digital camera, we succeeded in visualizing a beta-emitting nuclide of $$^{90}$$Sr-source on the 3-D model of the working environment.

論文

Visualization of radioactive substances using a freely moving gamma-ray imager based on Structure from Motion

佐藤 優樹; 峯本 浩二郎*; 根本 誠*; 鳥居 建男

Journal of Nuclear Engineering and Radiation Science, 7(4), p.042003_1 - 042003_12, 2021/10

Technology for measuring and identifying the positions and distributions of radioactive substances is important for decommissioning work sites at nuclear power stations. A three-dimensional (3D) image reconstruction method that locates radioactive substances by integrating Structure-from-Motion (SfM) with a Compton camera (a type of gamma-ray imager) has been developed. From the photographs captured while freely moving in an experimental environment, a 3D structural model of the experimental environment was created. By projecting the radioactive substance image acquired by the Compton camera on the 3D structural model, the positions of the radioactive substance were visualized in 3D space. In a demonstration study, the $$^{137}$$Cs-radiation source was successfully visualized in the experimental environment captured by the freely moving cameras. In addition, how the imaging accuracy is affected by uncertainty in the self-localization of the Compton camera processed by SfM, and by positional uncertainty in the gamma-ray incidence determined by the sensors of the Compton camera was investigated. The created map depicts the positions of radioactive substances inside radiation work environments, such as decommissioning work sites at nuclear power stations.

論文

A Concept of mirror world for radioactive working environment by interactive fusion of radiation measurement in real space and radiation visualization in virtual space

佐藤 優樹

Physics Open (Internet), 7, p.100070_1 - 100070_8, 2021/05

To understand radiation information, such as dose rate and the position of radioactive substances in a radioactive working environment in detail, the author proposes the construction of a mirror world of the environment. In the proposed mirror world, the work environment is reproduced in a virtual space, and the radiation information measured in a real space is projected onto the virtual space. Note that in addition to displaying the radiation information in the virtual space, the visualization result of the radiation information in the virtual space is used for decision-making in the real space. It is seen that the radiation measurement in the real space and visualization of measurement results in the virtual space always interact. In this report, the author introduces an example of building the mirror world based on radiation measurements performed in a laboratory using $$^{137}$$Cs as a radiation source. In the laboratory, the dose rate was measured by using a survey meter together with a device for the simultaneous localization and mapping based on three-dimensional (3D) light detection and ranging. The measured dose rate was mapped onto the work environment in the virtual space. Technologies developed by the author, for example, the 3D visualization of the radiation source based on an integration of the Compton camera and structure-from-motion technology and the virtual-reality experience technology of the work environment that displays the source image were also used. The technology to project the radiation-source image into the real space using augmented-reality is also introduced in this report.

論文

3D position and radioactivity estimation of radiation source by a simple directional radiation detector combined with structure from motion

佐藤 優樹; 峯本 浩二郎*; 根本 誠*

Radiation Measurements, 142, p.106557_1 - 106557_6, 2021/03

 被引用回数:2 パーセンタイル:23.22(Nuclear Science & Technology)

It is important to visualize radioactive substances' position and distribution and estimate their radioactivity levels to reduce the exposure dose of workers in radioactive areas (such as decommissioning worksites of nuclear power stations) and improve nuclear security functions. To visualize the radioactive substance's three-dimensional (3D) location, a directional radiation detector with a cylindrical shield on a simple single-pixel gamma-ray detector was applied to the structure from motion (SfM) technology using an ordinary digital camera. Verification was performed by a system that combines SfM with a CdTe sensor probe having narrow directivity. $$^{241}$$Am radiation source's position was visualized by drawing the radiation source's image acquired by the gamma-ray detector on the work area 3D model reconstructed through SfM. Furthermore, as SfM is a simultaneous localization and mapping technology, the system measures the gamma rays while measuring the gamma-ray detector's dynamic position and posture information. The measurements can be acquired while the gamma-ray detector is freely moving in the work area. These methods visualized the radiation source's position and quantitatively estimated the radiation source's radioactivity.

論文

Visualization of radioactive substances using freely moving gamma-ray imager based on Structure from Motion

佐藤 優樹; 鳥居 建男

Proceedings of International Youth Nuclear Congress 2020 (IYNC 2020) (Internet), 4 Pages, 2020/05

The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., suffered a meltdown as a result of a large tsunami triggered by the Great East Japan Earthquake on March 11, 2011. We have been conducting demonstration tests for detection of radioactive hotspots inside the FDNPS buildings using a Compton camera, a kind of gamma-ray imager. In this work, we introduced the 3D visualization of radioactive substances by using combination of the Compton camera and optical camera based on Structure from Motion (SfM). By taking photographs of the experimental environment while freely moving, a 3D structural model of the environment can be reconstructed from the multiple photographs, and the movement trajectory of the optical camera can be estimated simultaneously using the SfM. Furthermore, the radioactive substances can be visualized by drawing an image of the radioactive substances on the 3D structural model using gamma-ray data acquired by the Compton camera. In the demonstration, we succeeded in visualizing a $$^{137}$$Cs-radiation source on the 3D structural model of the experimental environment while freely moving these devices. This technology is useful for making it easy to recognize radioactive substances in decommissioning work site such as the FDNPS.

口頭

QRコードを使用した写真測量における推定パラメータに基づく複数局所点群統合

中村 啓太*; 馬場 啓多*; 渡部 有隆*; 松本 拓; 羽成 敏秀; 川端 邦明

no journal, , 

本研究では、QRコードを用いた写真測量による立体復元結果の部分間レジストレーションによる統合手法を提案する。写真測量で獲得した復元結果は、復元ごとにスケーリングが異なるため統合が困難である。この問題を解決するために、大きさが既知のQRコードを復元対象環境に配置し、QRコードの大きさに基づいて復元結果をスケーリングし、スケーリングした復元結果をQRコードのマーカに基づいて統合する。本提案手法を検証するため、全画像から復元した結果と複数の復元結果を統合した結果の精度を比較した。検証結果から、精度を維持しつつ写真測量による3Dマッピングに要する時間の短縮に有効であることが示された。

口頭

廃炉作業における3次元環境モデリングの計算効率改善のための画像選択手法の適用

羽成 敏秀; 今渕 貴志; 川端 邦明

no journal, , 

本講演では、廃炉作業に資する時系列画像に基づく3次元環境モデリングの計算効率を改善するための多峰性検出による画像選択手法について述べる。3次元モデリングの計算時間を短縮するために、時系列画像から3次元モデリングに適した画像を抽出することを試みた。この画像選択プロセスに統計的検定による多峰性検出を適用した。その結果、提案手法により抽出された画像から生成された3次元モデルは復元精度を維持したまま、生成時間を短縮することができた。この結果から、提案手法を用いることで時系列画像から適切な画像を抽出して3次元モデリングの計算時間短縮が可能であることが示唆された。これは、提案手法によって選択された画像は3次元モデリングの効率化に有効であることを示している。

口頭

Robust image selection method based on multi-modal detection for efficient 3D reconstruction from images

羽成 敏秀; 川端 邦明; 今渕 貴志

no journal, , 

本発表では、福島第一原子力発電所の廃炉作業における遠隔操作のために、多峰性検出によるロバストな画像選択手法を導入した画像に基づく3次元復元の結果について報告する。我々は、廃炉作業において遠隔操作ロボットのオペレータの空間認識能力を向上させるため、画像に基づく3次元復元手法の開発を行っている。オペレータの要求に応じて3次元復元モデルを提示するためには、3次元復元プロセスの計算コストの低減が必要である。そこで、3次元復元プロセスに画像選択プロセスの導入を試みた。我々は、時系列画像に対して提案手法を導入した3次元復元の検証を行った。その結果、時系列画像から適切な画像を選択することで3次元復元プロセスの計算量を低減し、オペレータの要求に応じて3次元モデルを提示するための3次元復元プロセスの高速化が実現可能であることを示唆している。

口頭

3-D mapping of air dose rate by combining freely moving survey meter and Structure from Motion

佐藤 優樹

no journal, , 

This presentation introduces the technique for 3-D mapping of dose-rate distributions in radiation-work environments. By combining a survey meter and Structure from Motion (SfM) technology, the values of the dose rate acquired by the survey meter are mapped on the 3-D virtual model of the work environment reconstructed by SfM. In addition, this method makes it possible to map the dose rate in the work environment while freely moving the survey meter. If the distribution of the dose rate can be visualized three-dimensionally, it is possible to reduce the exposure dose of workers and contribute to the planning of an efficient work plan.

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