Automatic System for Annual Ring Width Measurement and Application to Ancient Wooden Cultural Properties

任何树木年代学研究的基础都是测量年轮宽度的精度达到10 μm。传统的年轮读取器是固定的双筒显微镜装置，通常放置在研究实验室中，因此在测量实际标本时存在一定的局限性。据此，以扩大适用范围到更广泛、更多样的古木文物。有必要考虑其他测量年轮宽度的方法。在这方面，我们的目标是建立一个测量年轮宽度的半自动系统。在这个项目中，我们开发了这样一个系统，它使用最新的光学技术来间接获得年轮的图像，而不是直接测量实际物体上的环宽度。测试设备包括银盐相机、数码相机、扫描仪和软x射线摄影。据了解，在这些设备中，最适合于各种古代木制文化财产的是高分辨率数码相机。我们测量年轮宽度的方法是将数码相机拍摄的年轮图像导入计算机，并使用本项目开发的专用软件进行测量。该方法是非常有效的，虽然需要一些软件的修正，我们预计这将成为主流的年轮宽度测量。作为该项目的一部分，利用11m有效像素的单反数码相机，测量了位于京都宇治市的国宝宇治美真家神社的主神社和祭坛的年龄。结果证实，主神殿大约建于公元1060年，祭坛大约建于公元1290年。这项研究项目的成果可以应用于许多古老的建筑成员，各种大小的木制雕塑和各种艺术品，应该在建筑和艺术史的研究中发挥重要作用。

The basis of any dendrochronologic research is to measure annual ring width to an accuracy of 10 μm. Conventional annual ring readers were stationary devices with a binocular microscope and often stationed in research labs, therefore they presented certain limitations in measuring actual specimens. Accordingly, in order to expand the scope of application to a wider and more diverse range of ancient wooden cultural properties. it is necessary to consider other methods of measuring annual ring width.Our objective was, in this regard, to build a semi-automatic system for measuring annual ring width. In this project, we developed such as system that uses the latest optical technology to indirectly obtain an image of the annual rings rather than directly measure ring width on the actual object. The tested equipment included a silver salt camera, digital camera, scanner and soft X-ray photography. It was learned that, of these devices, the most suitable for a wide range of ancient wooden cultural properties was a high resolution digital camera.The method we employed to measure annual ring width was to import the ring image captured with a digital camera into a computer and perform measurements with purpose-specific software that was developed in this project. The method was very effective and, though some corrections are needed with the software, we expect this to become the mainstream in annual ring width measurement.As part of this project, the age of honden (main shrine) and haiden (altar) of Ujigami-jinja Shrine, a National Treasure located in Uji, Kyoto, was measured using a single lens reflex digital camera of 11 M effective pixels. Results confirmed that the main shrine had been built in about 1060 A.D. and the altar around 1290 A.D.The fruits of this research project can be applied to many old architectural members, wooden sculptures of all sizes and a diversity of artworks, and should play a major role in research into architectural and art history.