Volume Rendering is a technique that allows you to display all of the 3-D data at once. It is similar to an X-ray: Denser parts are more opaque. With Volume Rendering, you have control of the density of various data values.
The data in the following images is from a study of the gas dynamics of precessing dense supersonic jets. In fact, these were the first ever 3D simulations of precessing gas jets. Such jets are apparently commonly formed near very young stars. If we can understand how they propagate, they offer a powerful and unique tool to determine the environmental conditions around such stars. Their dynamics is, however, complex and until now largely unexplored. These simulations demonstrated, for example, that the entire precessing structure is enveloped by a "global" shock structure. This shields most of the jet structure from instabilities that have generally been thought to be disruptive. On the other hand these jets sweep up material inside the global shock, producing a very effective entrainment mechanism. The simulation was on a 256 x 256 x 256 grid.
Thanks to J. A. Cliffe, A. Frank and Tom W. Jones for providing the data files.
The data values are gas densities and range from 0 to 255. In these files, we want to see the precessing structure (the spiral) and the "global" shock structure that surrounds the spiral. To accomplish this, most of values of the gas densities are transparent. Usually, to get an image that shows what you want, some data values will have to be completely transparent. This is often requires several attempts to get it right.
Neither of these images seems to show any depths of the spiral. However a slight rotation brings this out.
For clearer, sharper images, an isosurface can be displayed. With an isosurface, a surface is constructed and the surface can be shaded.
More than one isosurface may be displayed at once. The "outer" isosurface is not opaque to allow the inner isosurface to be visible.
For this data set volume rendering is useful to see the relationship between the precessing structure and the shock structure. I could not use isosurfaces alone to get the desired effect. However, an isosurface and the volume in the first image rendered together is interesting.
All images on this page were produced using IBM Data Visualization Explorer.
This information is available in alternative formats upon request by individuals with disabilities. Please send email to alt-format@msi.umn.edu or call 612-624-0528. |
||||||||||||
|
HOME | QUESTIONS | FEEDBACK |
||||||||||||
|
||||||||||||