Study And Implementation Of Concrete CT Images Visualization Technology Based On VTK

In order to research the mechanical properties of concrete, which is non-homogeneous composite material, many people have already established the mathematical models of random aggregate to research and analyze microscopic damage mechanism of concrete. Although the shape and distribution of aggregate in these models has become more and more close to the real concrete structure, but they still have great differences from real concrete specimens. Therefore, more and more researchers hope to use more accurate method to reflect the real microstructure of concrete. This thesis puts forward the method of using scientific computing visualization and visualization toolkit VTK to complete three-dimensional reconstruction of concrete CT images, which provide a more effective and reliable method to research and analyze microscopic damage mechanism and mechanical properties of concreteThis thesis first introduces the VTK library in systematic, analyzes its object model, operating mechanisms and framework, then discusses the implementation process and principle of volume rendering techniques. Several commonly used volume rendering algorithms are realized using VTK, and their performances are summarized through comparing the experimental results. Secondly, the principle and implementation steps of classical volume rendering algorithm--ray-casting algorithm are researched in depth. At the same time, the thesis analyses its problems. On the basis of existing research, an improved ray-casting algorithm was proposed. The algorithm adopts the bounding-box technique and the intersecting algorithm related directly to x,y,z family planes to clip volume data and cast rays very effectively. It applies polygon scan conversion to reduce the number of cast rays; at the same time, the adaptive sampling method is used to avoid sampling the same voxel repeatedly. Experimental results show that under the premise of not affecting the image quality, the algorithm improves the speed of rendering greatly. Finally, it designs a visualization system of DICOM format concrete CT images .The improved algorithm is applied to the development process of this system. In this paper, arming at each function module, it provides the detail design and realization procedure, thus to show that the specialty and advantage of VTK in visualization development. And it also provides the practical basis that VTK toolkit can be much better applied in visualization development.