Visualising Animal Hard Tissues

点击翻译按钮获取中文摘要

From earliest times people have used hard skeletal tissues, such as bone, antler, ivory, horn, baleen (whalebone) and tortoiseshell, as raw material to create almost everything from simple tools to subtle and evocative works of art. Working these raw materials can greatly change their appearance and decay processes can render them almost unrecognisable. Today animal hard tissues have almost entirely been replaced as raw material for artefacts by metallic alloys and synthetic plastics, and wildlife conservation concerns have made some unavailable and unacceptable. With the passing of these raw materials, familiarity with their characteristics and properties has been lost, posing a challenge for those who work with historic and prehistoric artefacts, and to the detection of illegally trafficked, CITES protected materials. The correct identification of these materials is, however, fundamental to understanding the cultural significance, preservation needs and authenticity of these objects.Research is already in hand to refine and develop identification protocols through the collation, evaluation and validation of visual criteria and analytical techniques. This work has made great strides in improving our confidence in recognising, for instance, objects made in different species of ivory or in separating real tortoiseshell from fakes in horn or plastic. Using low-power microscopy, this can be done without the need to take disfiguring samples and at no risk to the object, by revealing the materials structure and patterns of degradation. However, like wood, these are complex 3D materials that can look and behave entirely differently depending on how they are worked and which aspects are revealed in the surfaces of an object. To interpret the evidence correctly it is necessary to understand the orientation of the object in terms of the material's natural structure. This is particularly difficult when similarly worked specimens of these materials are not available for comparison with the object being studied. Even if some of these raw materials, such as rhino horn, were available, it would be illegal (and questionable ethically) to prepare worked specimens. Using printed or web resources, illustrated by 2D diagrams and photographs to convey the detail of these complex structures, success largely relies on the ability of the user to think in 3D, and will not always lead to the correct identification. To overcome these problems, this project will develop a web-based resource for the 3D visualisation of the structures of these animal tissues. At its core will be a fully-rotatable 3D photo-realistic image of each raw material, a 3D diagram of its structure and 3D X-rays (CT scans) revealing the internal shape and structure. Zooming-in, the surface of the material can be explored at different scales with 'hot-spots' linking to photographs at a range of magnifications showing the structures revealed when it is cut in different directions, worked in different ways, fractured, aged or degraded. Once the correct material has been identified, it will be possible to orientate images of the object against the framework of the 3D model by matching the features revealed on the surface of an object with those indicated in the model. This will aid understanding of how the raw material was utilised and provide estimates of the size of the original tissue used, such as the minimum dimensions of the elephant tusk required to provide the material for a sculpture. Supported by on-line tutorials, this interactive visualisation resource will not only improve the accuracy of materials identification but will be an invaluable tool for researchers exploring the way that these raw materials have been used in the manufacture of artefacts, whether functional tools, devotional objects or fine art, across all time periods and geographical zones.