| Summary: | 碩士 === 國立臺灣海洋大學 === 資訊工程學系 === 95 === In this thesis, a new method for constructing uniformly distributed streamlines is presented. The method starts with superposing a hierarchy of regular grids upon the domain. At first, the coarsest grid is used to split the domain into cells. Seeds are placed in the cell centers. Streamlines are traced by using RK2 method. When integrating a streamline, if the separating distance between the current sample point and any previously computed streamline is too small, the integration is terminated, and another streamline tracing is triggered. Once all streamlines seeded in the current grid haven been computed, a finer grid is employed to split the domain; and a new round of streamline tracing begins. The whole process is completed if all levels of grids have been utilized. In order to enhance visual effects, we intentionally keep some short streamlines and render streamlines with tapering effect. Therefore, flow directions and detail pattern are revealed. A new approach is also developed to adaptively adjust time step size for RK2 method to increase accuracy. Our method estimates streamlines curvatures and prohibits streamlines to change their directions too much within one time step.
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