In April 2016, a severe earthquake occurred in Kumamoto, Japan. That damaged ISHIGAKI of Kumamoto castle and caused a large amount of stone to fall. We have developed support systems that use ICT and we have also investigated a method of extracting stone contour information. In our previous research, we have been improving GrabCut to try to automate stone contour extraction. However, in some cases, over-segmentation or under-segmentation occurred. In the paper, we dealed with this problem. From the observation results, it is considered that the stone shape has a convex polygonal shape to some extent. We set restrict regions for background-likely characteristics using a convex hull of a pre-extraction result by GrabCut close to the original iteratively. Convex hull fitness is a criterion to evaluate whether it is a convex polygon. In addition, the error with GT is calculated. From the results, the following can be considered. That with a small convex hull fitness value tended to have a small error with GT.

Authors and Affiliations

1. Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto, Japan

   Yuuki Yamasaki, Masahiro Migita, Go Koutaki & Masashi Toda

2. Toppan Printing CO., LTD., 1, KandaIzumi-cho, Chiyoda-ku, Tokyo, Japan

   Tsuyoshi Kishigami

Corresponding authors

Correspondence toYuuki Yamasaki,Masahiro Migita,Go Koutaki,Masashi Toda orTsuyoshi Kishigami.

Editors and Affiliations

1. Chonnam National University, Gwangju, Korea (Republic of)

   Hieyong Jeong

2. Aoyama Gakuin University, Kanagawa, Japan

   Kazuhiko Sumi

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