Research And Application Of 3D Geological Modeling Visual Computing And It's Parallelism

Visual computing can be concluded as the computing procedure which expresses data in computer graphical way, it involves multiple disciplines such as computer graphics, computer vision, artificial intelligence, programming design and software engineering. Visual computing can help people relieve from sea level data and discover the pattern behind it. As the development of the city construction and field engineering, a lot of geological information has been accumulated. Adopting proper data structure to built geological digital model and using scientific visualization technology to represent and interact with the model, geological profession can make precise explanation and analysis about the data, so as to improve the accuracy and reliability of geological analysis.Surface rendering and volume rendering are common techniques when rendering geological model. Surface rendering technique can help produce clear isosurface image, it is suitable for rendering the stratum which has obvious surface feature. But this technique could not reflect the inner detail of the whole data field. On the contrary, volume rendering can fix up this defect. This method is time consuming because of the large scale data and computation. As the development of parallel process architecture and parallel algorithm, plusing the inner parallelism of imaging processing, parallel visualization has became an important research area of improving the speed of volume rendering.This thesis studied modeling architecture and modeling method of 3D geological data. On the background of the need of geological application and geological exploration data, this thesis delved deeper about the organization of stratum data, the mathematic expression of space modeling. After analyzing and comparing recent popular modeling like surface model, volume model and surface-volume model, a stratum model which fits engineering geology has been proposed. This model is based on Object-oriented-design. It makes full use of Triangulated Irregular Net (TIN) and General Tri-prism (GTP) model.On the basis of researching and concluding the development procedure of volume rendering and its key technology, combined with multi-core cluster, a parallel ray casting volume rendering algorithm based on multi-hierarchical parallel programming model has been proposed in this thesis. This multi-hierarchical parallel algorithm has been used in 3D city shallow geological model successfully. According to the comparative experiments and the analysis of different computation scale on ray casting algorithm between the pure MPI programming model and the multi-hierarchical parallel MPI + OpenMP programming model, the results show that the multi-hierarchical parallel ray casting algorithm accelerates the volume rendering speed, the results also show the multi-hierarchical parallel MPI + OpenMP programming model has better performance than pure MPI programming model. In addition, this thesis researched the parallel mechanism supported by VTK and adopted real data to test the task parallism method and get good accelerating effect.Based on geological modeling and visualization algorithms, this thesis designed and realized the Geological Visualization System which includes four parts (data processing, data modeling, 3D geological visualization, user interactive). To develop this system, this thesis used open source platform QT and Visualization Tool Kit, integrate Visual Studio 2005 and adopt Object-oriented method. This system can provide display and user interactive function such as rotation, zoom in/out, clip, color bar, slice animation and isosurface extracting etc. This thesis processed and analyzed the theoretical model data, real bore-hole data and real seismic exploration data and get good results.