OKU Laboratory

Edible AR (E-AR) Marker

　

In Augmented Reality (AR) and Mixed Reality (MR), it is important to measure the position and orientation of objects in the real world. However, there were many difficulties in recognizing objects from images along, especially considering real-time processing. To make the recognition task easier in such cases, markers are commonly utilized. In particular, retroreflectors are often used as markers since they become very bright in captured images and are easy to be detected by image processing.  However, most conventional retroreflectors are made from glass or plastic. Thus, it has been difficult to apply them to some fields such as foods or inspection of the inner wall of digestive organs. Thus, we proposed an edible retroreflector made from kanten, or Japanese agar, which is a kind of transparent jelly.

The retroreflector itself can only work as a position marker. However, measurement of the 3D position and orientation of objects is essential for VR/AR applications. To satisfy this requirement, an edible AR marker made of the edible retroreflector is proposed. This AR marker, called an Edible AR (E-AR) Marker, works as a fiducial marker of position and orientation, which can be put on food.

AR markers typically have thick square borders of known size and a specific binary pattern inside the square to identify each marker. To fabricate this marker using the edible retroreflector, a specific shape of reflector needed to be fabricated. Thus, an optical stop with a desired shape made from opaque foodstuff was put on the surface of the edible retroreflector. We used a commercial chocolate slice which is a soft chocolate sheet in the shape of a thin slice and is easy to cut into the desired shape. A photograph of a prototype is shown in Fig.1, and the image of the prototype retroreflecting incident light is shown in Fig.2.

A dynamic projection mapping experiment with surface alignment of the projected image was conducted to demonstrate an example application of the E-AR marker.  A movie of this experiment is shown below, and sequence of photographs during this experiment is shown in Fig.3.