THREE-DIMENSIONAL SHAPE MEASUREMENT OF STRAWBERRIES BY VOLUME INTERSECTION METHOD

Strawberries are one of the most popular fruits in Japan, and are profitable for farmers because of their high price. However, much time and labor are required for harvesting, grading, and packing of strawberries, which has hindered the expansion of production scale, so the processes need to be automated. In this study, we developed a method of obtaining the 3D shape of strawberries in order to automate the grading and packing processes. The 3D shape of an object can be measured by using a laser scanner; however, the method is expensive and time-consuming. In this study, nine mirrors were set up around the object at an angle to reflect side views of the object, and the side views were taken simultaneously with a digital camera. The 3D shape was reconstructed from the nine side views by the volume intersection method, and was compared with data measured by a laser scanner. The results showed that the 3D shape of strawberries could be measured by the proposed method. The positional root mean square errors in the reconstructed contours were between 0.5 and 2 mm for most of the tested samples.