Research On Visualization Of Three-dimensional Core Based On VTK Technology

The core is the most intuitively, most reliably first-hand data which reflect the underground geological characteristics. In the basic research of geological exploration and development of petroleum, analysis of the microstructure of the core is an important research content. With the development of computer tomography technology and gradually mature, people can obtain two-dimensional images of the core through CT technology without damage to the core and reconstruct three-dimensional core based on this images.Based on the deep research of three-dimensional core through two- dimensional image sequences, this paper Realize the visualization of three-dimensional core drawing and on this basis to explore the analysis and processing method of cutting, sheet clipping and porosity calculation, and finally use the visualization tools of VTK.Net to design and implement three-dimensional visualization system of core. The main research work is as follows:1) Research the Marching cubes algorithm and the Ray casting algorithm for volume rendering, and use VTK technology to display three-dimensional visualization of core. Aim at the question of the experimental results of the Ray casting algorithm, we improve the algorithm from three aspects of adjusting the sampling distance, stopping the opacity and improving the image quality. The experimental results show that: two classical volume rendering algorithm both has its advantages, it can realize good visualization of three-dimensional core display; the Marching cubes algorithm focuses on the outside surfaces of core which is constructed on display, the Ray casting algorithm results in projection display better; from the point of view of drawing time and efficiency of the algorithm, the Ray casting algorithm is obviously superior to the Marching cubes algorithm; the improved Ray casting algorithm is certainly improved in rendering time, rendering speed and appearance display than the original algorithm.2) Based on three-dimensional visualization, we discuss three-dimensional cutting, sheet clipping and porosity calculation etc. By determining the cutting plane and the normal vector to achieve three-dimensional directional split core cutting operation; by constructing two clipping plane to achieve the thin plane clipping operation; deciding to the core value of the two images, we extract the pixels of different elements of value to do division and realize the porosity calculation for two-dimensional image core, then by isometric average interpolation method to further build the pixel ratio of volumetric data, the calculated three-dimensional core porosity, the approximate calculation of porosity. The verification of experimental results show that these methods are effective.3) Using visual graphics toolkit VTK, combined with Microsoft Visual Stdio 2005 as the development, we implement a simple three-dimensional core visualization system. The main function of the system includes two-dimensional core images data reading, displaying, three-dimensional visualization of three-dimensional interactive operation, core attribute information querying, three-dimensional cutting for the core, displaying and core porosity calculating, has certain availability.