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The Designing and Processing that Only Digital Technology Can Make it Possible. This is How 3D Scanning and AR Changed the Whole Concept of Bentwood
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An experimental attempt made by two architects

A bent hardwood with a beautiful curve. There are various factors for this curve. Some trees bend in the process of growing while ramifying into several branches and leaves one after another in search for light. Others bend at the bottom of the trunk due to the weight of snow on top of the trees on the slope. This is the unique aspect of snow country areas. Even though softwood also may bend under the weight of snow, they basically grow straight up due to the nature of the trunk as well as the tips of the branches growing faster. Bentwood was used in architecture as a beam to take advantage of their shape when people were living more closely with the nature at the level of living than they are now (source: http://shirakawa-go.org/zaidan/zaidan_files/2011k.pdf). In recent years the use of bentwoods are changing along with the way people live. Now they are used as pulp and fuel after being processed as chips.

Hidakuma challenged ourselves to the project of making use of bentwood by teaming up with an architect, Mr. Akinori Hamada, who specializes in design methods using computational design, Ms. Eri Sumitomo, who studies a new fabrication mechanism using augmented reality (AR), and Hida craftsmen. The method that cannot be realized without making full use of digital technology has changed the way of processing and utilization of bentwood. As a result, the new structure called “Torinosu (bird nest)” was created, where six logs support each other to stand on their own.

In this article, we will introduce you to a product called Torinosu, installed on the terrace of the cafe “Bread, Espresso and Meetup” in Miyashita Park, Shibuya, Tokyo, as well as the production process that combines digital technology and craftsmanship.

Project Overview

  • Support Details:
    Bentwood survey and procurement / Design and production support
  • Duration: April – August 2020 (production duration)
  • Team Organization:
    Client: Cafe “Pan to Espresso to Machiawase” (Operated by Jisoku ichi jikan (Architect) and HitoBito Inc. (Architect))
    Design: Aki Hamada Architects (AHA)
    Technical support: ERI SUMITOMO ARCHITECTS
    Production: Yanagi Mokuzai (Timber shop) and Calm’s (Woodwork Studio)
    Cooperation: Hida City Forestry Association and Oku Hida Kaihatsu (Estate development)


Designs that bring people together as well as create a variety of activities

Torinosu has a self-supporting structure that six bent logs support one another by the reciprocal frame structure*. We used 6 types of wood, such as water oak and Japanese hackberry. The logs, which bend, twist, and undulate as they grow, retain their wild beauty, as well as natural presence that makes you feel like touching them.
The height at which the logs overlap is different at each spot, and it is designed to be used in several different ways according to the occasion. The cut surface can also be used as a table by the processing and installing using AR technology.

Torinosu, being installed near the entrance of “Bread, Espresso, and Meetup”, is popular with many people, including cafe customers taking a break, people passing by the street while taking notes, and kids climbing on it. Born from a project that includes many unprecedented attempts, Torinosu shows us the appearance of a bentwood that has never been seen before as a product.
* Reciprocal frame structure: a structural form in which materials are supported with one another while preventing the concentration of the materials at one contact point.

Materials: Oak, Japanese hackberry, Magnolia kobus, Giant dogwood, Birch and Magnolia hypoleuca
Size: W2580 x D2660 x H1090
Finish: Overcoat of outdoor waterproof, insect repellent, mildew proof, UV proof and anti-crack coating (Xyladecor, etc.)


Flexibly created design by heavy-weight logs

Hidakuma showed Mr. Hamada around Hida in October 2019. We visited Ikegahara forest, where the tree leaves were about to turn red, sawmills, and architects who build houses with hardwood. Then, Mr. Hamada turned to me for advice, hoping he could use bentwood for the project as much as possible. We aimed not only to create structures that make use of bends, but to prove that any bentwood can be used to design precisely by utilizing digital technology. As a result, with the cooperation of the Hida City Forestry Association and Oku Hida Kaihatsu, bentwoods were collected from the forests in the Hida area.

The bentwoods were collected at Yanagi Mokuzai yard.

The Hidakuma staff striped bark for accurate 3D scanning.

Scanning was performed by blocking the light with a blue sheet, as ambient light also affects 3D scanning.

First, we performed 3D scanning of the felled logs. By acquiring 3D data even for logs weighing several hundred kilograms, you can simulate designing and processing while freely moving and manipulating in digital space. Structural calculation was also carried out based on the data. That is how the design drawing of Torinosu was completed.

Source: AHA

A space where the reality intersects with digital

An AR device called HoloLens was used to process the logs based on the design drawing. With the shape like a goggle, it superimposes a virtual space on a real space, making it possible for both real and virtual objects to coexist in real time. In this project, the cut surface was graphically highlighted in the real space in order to guide the processor. Usually, carpenters and furniture makers perform “layout” to mark the wood for processing purposes. However, it is not easy to perform the layout on a bent log accurately with human hands to process accordingly. Therefore, we used HoloLens to perform “digital layout”.
However, 3D data does not immediately emerge in a real space with HoloLens. By adding the coordinate information for arranging the logs to the 3D data during processing, as well as placing the logs at those coordinates even in the actual real space, the 3D data that emerges in the real space through HoloLens overlaps the actual logs.

The reality and the virtual reflection overlap with HoloLens.

Mr. Kazunori Yanagi from “Yanagi Mokuzai”, who runs a lumbering work in Hida, was in charge of log processing with HoloLens. Even though Mr. Yanagi was used to handling chainsaws, he was nervous about his first attempt at his work with HoloLens as the chainsaw used for this project was heavier than usual. Chainsaw processing using this AR technology is possibly the first case in the world and Japan.
Mr. Hisatoshi Katada, a woodworker from Hida Furukawa, was in charge of drilling necessary for assembly with HoloLens. In particular, for the degree of sharpness of the surface where logs come into contact with each other, it was difficult to increase the precision with digital technology. Therefore Mr. Katada’s craftsmanship was necessary while using AR.

Mr. Hisatoshi Katada, a woodworking craftsman wore HoloLens for log processing.

While logs can be moved easily on a computer, a considerable amount of manpower was required to move them in reality. At the installation site, 8 people worked through the process from carrying out to installation. HoloLens was used to assemble the logs as well before Torinosu was completed.

HoloLens was used as a guide when assembling on-site.

This project required an approach to expand the use of the material, “bentwood”, which is currently limited in its use, while taking advantage of the natural characteristics through digital technology. Hidakuma will continue to work with partners both inside and outside the region to come up with unprecedented ways to make most of the forest, and eventually put trees into practice.


Aki Hamada
Architect / CEO of Aki Hamada Architects Inc.
1984  Born in Toyama prefecture, Japan
2010  Tokyo Metropolitan University, BA
2012  University of Tokyo, MA Architecture
2012  Established studio_01 with Alex Knezo
2014  Founded Aki Hamada Architects
2014  Joined teamLab Architects as partner
2014-2016 Part-time Lecturer at Nihon University

Eri Sumitomo
Designer | Researcher / CEO of ERI SUMITOMO ARCHITECTS
1986 Born in Tokyo, JAPAN
2006-2010 Department of Architecture at The University of Tokyo
2010-2014 Chiba Manabu Architects
2016- UK
2017-2018 Architectural Design MArch at the Bartlett School of Architecture
2019- Senior researcher at Keio University SFC

Kotaro Iwaoka
President and CEO of Hidakuma Inc.
Born in 1984. After graduating from Chiba University, Iwaoka engaged in designing private houses and apartment complexes at an architectural company. Then he went back for a graduate study at Keio University, researching and producing digital design products.
In 2011, Iwaoka started working at Hidakuma, wishing to create a cafe “Fab Cafe” that offers a creative designing environment. By 2012, as  the planning and operating director, he successfully opened FabCafe in Shibuya, Tokyo, where digital design products are being created. He also joined in 2015 to start up half-governmental and half private company, Hidakuma Inc., (official name: Hida no Mori de Kuma wa Odoru) in cooperation with Hida city of Gifu prefecture. 2016 saw a FabCafe opened in the same city. He has been taking up new projects based around the forest resources. In April 2018, Iwaoka became vice president and CEO of the company, then in March 2019, he became the president and CEO of the company.

Hideaki Asaoka
Works at Hidakuma Co., Ltd. Born in Hida City, Gifu. After graduating from Nagoya University of the Arts, he experienced furniture making and design at furniture makers and interior design offices. He participated in Hidakuma in 2016, being in charge of a wide range of projects including product development, design, production, and construction. With a wide range of knowledge on wood and deep respect for craftsmanship, he continues to make great efforts every day to add new value to the wood.

Member’s voice

We went to Hida forest to look for trees for production. There we encountered bent trees that grow on the slopes. Each of them had a very smooth curve. Although bent trees were once often used for beams in buildings, nowadays they are used as chips as they are difficult materials to handle.
The processed trees can be bent with steam or can be cut three-dimensionally to create a curved surface. However, when I saw bent trees in the forest, I wondered if we could precisely use the beautiful, vibrant curve for what it is in the design.
We perform 3D scan on a wood to handle the complex shape three-dimensionally to use it precisely. Subsequently, AR technology using HoloLens facilitates the layout process. This architectural object is realized by combining advanced craftsmanship and AR technology. The structure of Reciprocal frame principle can help realizing heavy woods weighing more than 150 kg supporting one another and standing on their own.
Humans have managed to rationalize and control the forms and powers of nature so that they could be easily handled for humans. From now on, I would like to envision a future in which nature and humans can coexist and be enriched at a higher level. I hope this architecture will symbolize such a world, offering an opportunity for people to think about the future ecological system.

Aki Hamada
Aki Hamada Architects Inc.

Fabrications applying AR technology are widespread in the architectural industry. By installing AR devices such as HoloLens, reality can expand its scope, enabling a new way of manufacturing.
In such productions, interestingly, not only cutting-edge technology, but also the “sense” of human beings does matter. Even with a 3D hologram visualized by AR, it can not offer the complete product. There are always “fluctuations” affected by accuracy and the environment. While using AR as a guide, human beings still continue to think, make trial and error, and make intuitive judgments for manufacturing. In the end, when you look at the finished product, you realize that you have accomplished a work that was never easily realized before.
Torinosu is the project in which you can enjoy the best part of these technologies throughout the work. Each bentwood is designed by 3D scanning, AR layout, and AR alignment. With the complexity of materials being covered with digital technology, combination of craftsmanship and knowledge of wood has created the new value of bentwood that has never been utilized in its original form before.
The work created by using these technologies will create an opportunity for us to rediscover the value of human beings and natural objects. I would like to continue to be involved in such productions.

Eri Sumitomo

Here is my thought – “this project indicates a reasonable approach for making the best use of Hida’s hardwoods.” One of the major issues in the forest industry (particularly with hardwood) is that the price of timber is too low, which is preventing economical independence of the industry. Only a handful of good quality furniture timber is traded at a reasonable price. For other miscellaneous timbers, even if they are cut down and brought to town, they are probably in the red at that point. If we can raise the price of miscellaneous timbers that meet certain conditions, we can create an opportunity for the industry to grow. If we cannot find any value in existing material processing methods, we had better try using different technologies and tools. They are the 3D scanner, AR goggles, 3D modeling and structural calculations on the computer. This time, in our policy, we have set a criteria that a wood with a higher level of bend becomes more useful. It’s completely opposite from existing value standards. The optimum overall shape (structure) is derived from the shape of each bentwood. Therefore we can save the trouble of turning it to a plate-shaped intermediate material, minimizing the amount of mill end scraps generated during processing in advance. If we can raise the price of timber and eliminate the waste at the same time, I would say this is the most reasonable way for the forest industry in the new era.
Not a few people have doubts about not seeing bifurcated radishes or bent cucumbers. Some people may sympathize with restaurants trying to solve the issue of the agricultural industry by focusing on those vegetables not distributed, as well as actively making the best use of them. Now we have encountered a similar situation in the forest industry as well. I don’t believe that we can make use of all the trees and save the entire forest industry with this method. However, we would like to improve the value of the forest in the future by enhancing both the quality and quantity of furniture materials through forest management, while increasing the value of some of the miscellaneous woods.

Kotaro Iwaoka
President and CEO of Hidakuma Inc.

When you are manufacturing products with a laser cutter or 3D printer, some people say “You should not rely on these things”, “true craftsmen should make things with your own hands”, or “our skills will not be needed any longer.” People have been complaining saying “young people these days (are not like us)…” since the ancient Egyptian era. I would imagine people had the same sort of conversations when people used to use their own hands for tree cutting and then the electric circular saw was introduced.
Appearance of new technologies will certainly take away the work we have done so far from us. However, new technologies create new ways of expression. The appearance of electric woodworking machines made it possible to handle super-hard-wood that was never used for production before. As a result, people started making finer and more delicate furniture by taking advantage of its hardness.
Without AR, this project would have required a great deal of time and effort to process woods with different sizes and curved surfaces at a certain angle and dimensions. Without understanding the shape of a log on the computer by 3D scanning, you would have ended up physically turning over a 100 kg log, which would have taken half an hour or so, and gone through the same verification process endlessly.
HoloLens and AR positioning have made it possible to perform such simple tasks in dramatically more efficient manner. However, that’s not the only essence. Now we can spend more time on processing work that cannot be completed by technology alone, as well as can only be completed by skilled craftsmen. Craftsmanship and skills are still required for delicate work to check the flow of the grain, or to adjust the amount of force according to the feel transmitted to the hands.
As for materials, now we are able to add value to the ones whose price was previously beaten down.
I would assume new technologies will continue to appear one after another. Accordingly, the work of craftsmen will increase more rather than decreasing. Most importantly, the creator is a creature who can find the utmost joy when he/she learns a new technique.

Hideaki Asaoka

Text: Takeya Shida
Photo: Gottingham

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