Edible Retoreflector
A retroreflector is a kind of optical device that can reflect incident light back to the light source. A retroreflector is often used as an optical marker for machine vision since it becomes very bright in the scene and is easy detect by image processing.
Most conventional retroreflectors are made of glass or plastic. Thus, it is difficult to apply them to some fields such as foods or inspection of the inner wall of digestive organs, because there is the risk of accidental ingestion of the device, which may cause severe health problems. However, the visual recognition of foods seems to have many potential applications, such as projection mapping on foods. Also, the recognition of the inner wall of digestive organs is important for medical inspection. If it were possible to make an edible retroreflector, such a retroreflector would be expected to be suitable for these applications.
Based on this idea, we propose an edible retroreflector made from transparent foodstuffs. We found that kanten, or Japan agar, which is a traditional Japanese cooking ingredient used to form a transparent jelly, was suitable for forming such optical devices. A recipe for an edible retroreflector using kanten was developed. A prototype made from kanten showed a retroreflective function in reflectance measurement experiments. Dynamic projection mapping on a Swiss roll was also successfully demonstrated using the prototype as an optical marker.
Movie. The appearance of the prototype of the edible retroreflector, and the result of dynamic projection mapping on a swiss roll using the prototype.
Fig. 1. Photograph of the prototype.
Fig. 2. Photograph of the object for projection mapping experiment (left), and a photograph of the swiss roll with projected letters (right).
References
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Hiromasa Oku, Takahiro Uji, Yiting Zhang, Kumi Shibahara : Edible fiducial marker made of edible retroreflector, Computers & Graphics, Vol.77, pp.156-165 (2018) [doi:10.1016/j.cag.2018.10.002]
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Takahiro Uji, Yiting Zhang, and Hiromasa Oku : Edible Retroreflector (Full Paper), 23rd ACM Symposium on Virtual Reality Software and Technology (VRST ’17) (Lindholmen Conference Centre, Gothenburg, Sweden, 2017.11.08) / Proceedings [doi:10.1145/3139131.3139148] (acceptance rate 21%) (Best Paper Award)