Browsing by Author "Jang, Hajun"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Dynamic acceleration structures for the visualization of time-dependent volume data on the GPU
    (2015) Jang, Hajun
    Volume rendering extensive 3D data is requiring much computing power and doing this efficiently has been a challenge. To build a data structure of which rendering can take advantage is a common solution. Among others these data structures are built with the purpose of empty space skipping and adaptive sampling. Empty space skipping is the main strategy of acceleration in this work. Octree and Kd-tree is constructed and analyzed in reference to construction and rendering performance. Time-dependent data often come from numerical simulation and show similarities between two successive time instances. These similarities can be exploited to facilitate construction. The method and consequences of this exploitation will be discussed. Naive volume rendering is conceptually suitable for parallel computing. On the other side, both constructing and traversal of hiearchical data structures do not seem to agree with parallel nature of GPUs. Still implementation techniques to bypass GPU-specific traps of performance is applied in order to utilize the enormous computing power of GPUs.
  • Thumbnail Image
    ItemOpen Access
    Glyph-based 2D flow visualization
    (2013) Jang, Hajun
    Flow visualization is an important topic in scientific visualization. The focus of this work is to visualize 2-dimensional vector fields with existing Flow Radar Glyphs and field lines, mainly with pathlines. The idea of Flow Radar Glyphs is to visualize time-dependent data into a compact glyph. Flow Radar Glyphs show the Flow, and can be applied to other vector field properties. Tangents along pathlines are implemented as Flow Radar Glyphs (further referred to as 'tangential glyphs') in this work. More than one Pathlines in a data domain depicted in original size can intersect many times, therefore it is hard to keep them visually separated. In this work, the idea to solve this problem is to implement downscaled pathlines. Downscaled pathlines will be demonstrated and their gains will be examined. Another attempt to demonstrate the characteristics of pathlines are the tangential glyphs. Downscaled pathlines and tangential glyphs are the 2 focuses of this work. The visualization is implemented in C++, using OpenGL and GLSL compute shader. In the first place, the data sets are loaded into texture memory, in order to be accessed from the shader that can compute interpolations between seeding points using texture coordinates. The regular grid, on which the data is defined, makes the implementation in threads comfortable. For user interaction and instantaneous variable change and apply, AntTweakBar is used.