1. OpenGL Visualization of Hurricane Isabel
Gregory P. Johnson, Christopher A. Burns
Texas Advanced Computing Center
The University of Texas at Austin

2. Goals
Visualize the Hurricane Isabel dataset with the following three criteria:
Multiple Characteristics
Interactivity
Exploration

3. Our Solution Standalone C++/OpenGL application
Standard language, APIs ==> Portability
Pthreads for multithreading
FLTK Toolkit for GUI widgets
Make use of modern GPU hardware
Our solution runs on a standard desktop PC in real time

4. Multiple Characteristics
Clouds
Billboarded quads
Opacity, luminance are functions of data
Precipitation
Color-coded spheres for snow, rain, and grauppel
Easily distinguished from clouds
Wind
Horizontal slicing plane
Colored either by wind direction, or wind magnitude
Enable or disable any combination of the three visualizations

5. Interactivity Challenges
Limited I/O Bandwidth
Very large files
Load data in a separate thread
Prefetch the next timestep
Sorting of cloud particle quads
Correct alpha blending requires sorting, sublinear performance
Organize voxel data in memory as 3D tiles
Sort quads in each tile, then sort the tiles
Good memory performance

6. Exploration Camera can move anywhere at any time
Transfer functions user-adjustable
Can pause simulation at any time, or advance to any timestep
Slicing plane altitude is user-adjustable

7. Wind vector colors are mapped to the compass directions above
Gallery
Warmer wind vector colors indicate wind magnitude. Notice the sharp falloff of wind magnitude in the eye, heavy precipitation to the north.
Wind vector colors are mapped to the compass directions above