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| Presentation | 2026-03-02 14:00 [Poster Presentation] Inner diameter tuning based on CT image brightness of Shakuhachi and evaluation of reproduction by additive manufacturing Mizuki Nakao, Soichiro Sudo, Akisato Mizuno, Yoshinori Takahashi (Kogakuin Univ.)  EA2025-88 SIP2025-108 SP2025-41 |
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| Abstract | (in Japanese) | (See Japanese page) |
| (in English) | Protection of cultural heritage from natural disasters and military conflict requires techniques that can accurately record and reproduce the shapes of cultural heritage objects. Yamamoto et al. created a three-dimensional model of a classical oboe made around 1800 using X-ray CT scanning, reproduced it by additive manufacturing, and evaluated its sound quality. Similarly, Kuramoto et al. attempted to reproduce a shakuhachi using a comparable method. In shakuhachi, differences in X-ray attenuation occur in the composite layers of lacquer and plaster applied to the bamboo body, as well as on the inner surface of the tube. In such cases, the most common approach is to determine a threshold using Otsu’s method based on the histogram of brightness values in CT images. However, edge extraction based on a single threshold can lead to problems, such as narrowing of the inner diameter in regions with high reflectivity or the formation of cavities in low-density areas of bamboo, depending on the selected threshold. In this study, the images were binarized using a threshold determined from the valley of the luminance histogram, and objects with closed boundaries in the resulting binary images were extracted. A masking pattern for the inner hole of the tube was generated based on variations in the perimeter of the extracted objects and the radial distance from the image center to the object boundary. By adjusting the size of this masking pattern, correction of the tube’s inner diameter was attempted. Subsequently, the instrument was reproduced using a 3D printer based on vat photopolymerization. To verify the fidelity of reproduction, the inner diameter and harmonic structure of the reproduced shakuhachi were compared with those of a shakuhachi previously reproduced using Otsu’s method and the original shakuhachi. Although the inner diameter of the shakuhachi reproduced using the proposed method more closely matched that of the original than that reproduced using Otsu’s method, some discrepancy remained. In contrast, the harmonic structure of the shakuhachi reproduced using Otsu’s method was closer to that of the original shakuhachi. | |
| Keyword | (in Japanese) | (See Japanese page) |
| (in English) | Protection of cultural heritage / air-reed instrument / shakuhachi / CT image / additive manufacturing / / / | |
| Reference Info. | IEICE Tech. Rep., vol. 125, no. 369, EA2025-88, pp. 93-98, March 2026. | |
| Paper # | EA2025-88 | |
| Date of Issue | 2026-02-23 (EA, SIP, SP) | |
| ISSN | Online edition: ISSN 2432-6380 | |
| Copyright and reproduction |
All rights are reserved and no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Notwithstanding, instructors are permitted to photocopy isolated articles for noncommercial classroom use without fee. (License No.: 10GA0019/12GB0052/13GB0056/17GB0034/18GB0034) | |
| Download PDF | EA2025-88 SIP2025-108 SP2025-41 |
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| Conference Information | |
| Committee | SP EA SIP IPSJ-SLP |
| Conference Date | 2026-03-02 - 2026-03-04 |
| Place (in Japanese) | (See Japanese page) |
| Place (in English) | |
| Topics (in Japanese) | (See Japanese page) |
| Topics (in English) | |
| Paper Information | |
| Registration To | EA |
| Conference Code | 2026-03-SP-EA-SIP-SLP |
| Language | Japanese |
| Title (in Japanese) | (See Japanese page) |
| Sub Title (in Japanese) | (See Japanese page) |
| Title (in English) | Inner diameter tuning based on CT image brightness of Shakuhachi and evaluation of reproduction by additive manufacturing |
| Sub Title (in English) | |
| Keyword(1) | Protection of cultural heritage |
| Keyword(2) | air-reed instrument |
| Keyword(3) | shakuhachi |
| Keyword(4) | CT image |
| Keyword(5) | additive manufacturing |
| Keyword(6) | |
| Keyword(7) | |
| Keyword(8) | |
| 1st Author's Name | Mizuki Nakao |
| 1st Author's Affiliation | Kogakuin University (Kogakuin Univ.) |
| 2nd Author's Name | Soichiro Sudo |
| 2nd Author's Affiliation | Kogakuin University (Kogakuin Univ.) |
| 3rd Author's Name | Akisato Mizuno |
| 3rd Author's Affiliation | Kogakuin University (Kogakuin Univ.) |
| 4th Author's Name | Yoshinori Takahashi |
| 4th Author's Affiliation | Kogakuin University (Kogakuin Univ.) |
| Speaker | Author-1 |
| Date Time | 2026-03-02 14:00:00 |
| Presentation Time | 80 minutes |
| Registration for | EA |
| Paper # | EA2025-88, SIP2025-108, SP2025-41 |
| Volume (vol) | vol.125 |
| Number (no) | no.369(EA), no.370(SIP), no.371(SP) |
| Page | pp.93-98 |
| #Pages | 6 |
| Date of Issue | 2026-02-23 (EA, SIP, SP) |
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