Stability Tests

Trying to make statements about the comparison of variants one has to minimize the influence of the numerical and physical instabilities first. So the points where such instabilities occur have to be detected and visualized. At the institute for algorithms and scientific computing (SCAI) of the project partner GMD a deformation function has been developed evaluating the displacement of a mesh node relative to its neighbourhood. The standard deviation of this deformation of the mesh over several simulation runs can finally be visualized on the deforming geometry.

Evaluating this visualization the problem was up to now to find the places where an instability has formed. With crashViewer here too visualization with the aid of a onedimensional index texture (see also selective masking of the geometry by RGB textures) is a good solution. Using the transfer function editor displayed below the geometry can be blended out interactively where the deformation of the mesh behaves in a stable way over all simulation runs. So the initial points where instability occurs become visible at once.
In addition the user is able to fix the camera at such points to observe the development even with the whole geometry displayed. This approach supports the engineer in quickly finding and evaluating the instabilities occuring within the same model over several simulation runs.

The transfer function editor allows the user utilizing an index texture to interactively change the colouring of different ranges of parameters. Furtheron it allows the modification of the texture environment so the settings of the transfer function regarding the alpha function does not only have effects on the display of the texture, but with simultaneous activation of the alpha test also has effects on the reprensentation of the geometry. This technique permits the selective visualization depending on the displayed parameter values.

still at work...