A Study on Object Modeling for X-ray CT based Engineering

本研究以X射线CT扫描仪为对象，研究了先进数字工程系统的建模方法。我们特别感兴趣的是在生成三角形网格或其他形式的表面信息，从CT数据，它可以用于数字工程系统。用于这种网格生成的一种标准方法是所谓的“等轮廓”方法。在这个为期2年的项目的第一年，我们开发了一种方法来同时生成不同材料部件之间的边界表面。它可以应用于这样一个机械零件，如汽车发动机缸体，这是由铁和铝。这种方法是基于三维图像分析的材料分割，也是我们的创新轮廓方法的基础上，我们的“匹配立方体”的理论。在第二年，我们集中在薄板结构的建模技术。重点研究了从CT数据中提取内侧面的方法。内侧表面， 关于我们 可供设计人员设计薄板结构时参考。因此，从CT图像中提取它们的需求很大。我们的方法是混合体建模和网格建模相结合。我们首先提取与内侧表面相关的体素。然后，我们应用我们的轮廓算法生成一个三角形网格的内侧表面。由于我们还可以提取薄板结构的边界面，因此可以评估薄板的厚度分布。在我们的工业应用中，精度是相当重要的。我们设计和制造特定的样品（体模），以检查我们的内侧表面的准确性。实验结果表明，该方法的中间面精度与边界面精度相当，并对焊接件进行了数值模拟。薄板结构通常由多块薄板焊接而成。使用X射线CT，不可能从图像中识别这种焊接部分。然而，在数字工程应用中，焊接前每个单独部件的网格和焊接位置的信息是重要的。因此，我们研究了一种方法来分离的CT数据的一个复杂的焊接组件到它的部分。虽然仍有困难的问题，我们已经成功地为典型的焊接零件。少

In this research project, modeling methods to be used in advanced digital engineering systems based on X-ray CT scanner are investigated. Our particular interest is in generation of triangular meshes or other forms of surface information from CT data, which can be used in the digital engineering systems. One standard methods for this mesh generation is so-called "iso-contouring" method. In the first year of this 2 year project, we developed a method to generate boundary surfaces between different material parts simultaneously. It can be applied to such a mechanical part as automotive engine blocks which are made of iron and aluminum. This method is based on three dimensional image analysis for material segmentation and also on our innovative contouring method based on our "Matching Cubeablity" theory.In the second year, we were concentrated on modeling technologies for thin plate structures. Particularly we studied methods for extracting medial surface from CT data. A medial surface is … More useful for designers to design thin plate structures. So there is large demand to extract them from CT images. Our method is hybrid by combining volumetric modeling and mesh modeling. We first extract voxels which are related to the medial surface. Then we apply our contouring algorithm to generate a triangle mesh for the medial surface. Since we can also extract the boundary surface of the thin plate structure, thickness distribution of the thin plate can be evaluated. In our industrial applications, accuracy is rather important. We design and manufacture specific samples (phantom) to examine the accuracy of our medial surface. Our experiment shows that the accuracy of the medial surface is as good as that of the boundary surface.Furthermore we are working on the problem of welded parts. A thin plate structures are usually made of several pieces of thin plate which are welded together. Using X-ray CT, it is impossible to identify such welded part from the images. However, in digital engineering applications, meshes for each individual part before welding and information about the welding positions are important. So we studied a method to separate CT data of a complex welded assembly into its parts. Though there are still difficult problems, we have succeeded for typical welded parts. Less