| FIRST: A Flexible and Interactive Resampling Tool for CFD Simulation Data |
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We introduce a flexible tool for interactive resampling of computational fluid dynamics (CFD) simulation data on versatile grids. The tool and coupled algorithm afford users precise control of glyph placement during vector field visualization via six interactive degrees of freedom. Other important characteristics of this method include: (1) an algorithm that resamples any unstructured grid onto any structured grid, (2) handles changes to underlying topology and geometry, (3) handles unstructured grids with holes and discontinuities, (4) does not rely on any pre-processing of the data, and (5) processes large numbers of unstructured grid cells efficiently. We believe this tool to be a valuable asset in the engineer’s pursuit of understanding and visualizing the underlying flow field in CFD simulation results.
Visualizing the direction of the flow, including the normal components, using the classic hedgehog visualization technique can result in perceptual problems such as visual complexity and occlusion. Here the problems are illustrated in a slice through the intake port data set with semi-transparent context information.
Visualizing the direction of the flow, including the normal component, using FIRST. The resampling grid is outlined in white.
Visualizing the direction of the flow through a cylindrical slice from CFD using a brute force hedgehog technique.
Visualizing the direction of the flow, including the normal component, using the polar resampling option of FIRST.
A slice mesh with discontinuities -two gaps in the shape of rings, using hedgehog visualization.
The same slice resampled onto a regular grid.
| Description of Animations | Original, high resolution, higher quality MPEG, for use with Linux and those Windows PCs with the latest version of Windows Media Player, Quicktime Player, or RealOne Player | Low resolution, low bandwidth, lower quality MPEG for Windows PCs with older versions of Windows Media Player |
| This animation shows 2 interactive translation degrees of freedom (DoF). The very first frame shows the perceptual problems (visual complexity and occlusion) associated with viewing the vector field with normal component using a brute force hedgehog visualization (for comparison). Then the user turns on the resampler, changes the resolution, and translates the resampling grid. | 640 x 560 (3.4 MB) | 640 x 480 (1.5 MB) |
| This animation shows the rotation DoF. | 640 x 560 (6.8 MB) | 640 x 480 (1.7 MB) |
| This animation shows the 3rd translation DoF that requires dynamic resizing of the resampling grid with changes to both the (underlying) topology and geometry of a ring mesh from CFD. When the size of the resampling grid becomes to small, the user lowers the resolution. | 640 x 560 (3.9 MB) | 640 x 480 (1.5 MB) |
| This animation shows another example of the 3rd translation DoF that requires dynamic resizing of the resampling grid with changes to both the (underlying) topology and geometry of a disconnected mesh -the connecting pipes of an intake port. When the size of the resampling grid becomes to large, the user increases the resolution and also the scaling factor of the vector glyphs. | 640 x 560 (4.4 MB) | 640 x 480 (1.5 MB) |
| This animation shows an example of polar resampling and the 3rd translation DOF through the ring data set. Again, the very first frame shows the perceptual problems associated with trying to view the flow field (with normal component) using a brute force hedgehog technique (for comparison). | 640 x 560 (3.9 MB) | 640 x 480 (1.5 MB) |
| Polar resampling and the 3rd translation DoF through the combustion chamber of an intake port -a larger data set. Conceptually, this 3rd translation DOF acts as a probing tool. | 624 x 560 (2.4 MB) | 624 x 480 (1.5 MB) |
| The use of FIRST for unsteady flow visualization with the normal component of the slice. | 656 x 592 (2.0 MB) | 640 x 480 (0.7 MB) |
| Another example of unsteady flow visualization with normal component. | 656 x 592 (2.0 MB) | 640 x 480 (0.7 MB) |
| A 3rd example of unsteady flow visualization with normal component. Note the ripple effect along the long edges of the slice. | 656 x 592 (1.9 MB) | 640 x 480 (0.7 MB) |
In case of questions, comments, etc., please send email to Laramee "at" VRVis.at.