Chapter 4 Vortex detection - Computer Graphics and Visualization

Chapter 7
Conclusions and future work
Starkt, evigt och starkt 1
är v˚agornas väldiga t˚ag,
och stark av det eviga havet
var mjuk förgänglig v˚ag.
The preceding chapters in this thesis describe techniques for extracting and visualizing
features, i.e. interesting and characteristic phenomena in a data set, using geometries,
which are curves, surfaces and solids. Three types of techniques have been covered:
particle tracing, vortex detection, and deformable surfaces. In this chapter, we draw
conclusions and give directions for future research.
7.1 Conclusions
Particle tracing
In Chapter 3, we described particle tracing, a technique to visualize velocity fields by
simulating the release of massless particles and calculating their trajectories. We concentrated
on particle tracing in various types of special grids: structured curvilinear
grids, -transformed grids, and unstructured grids. In these grids, point location, the
process of finding which grid cell contains a given point, is more difficult.
In structured curvilinear grids consisting of hexahedral cells, decomposition of the
cells into 5 tetrahedra usually works well. In -transformed grids, a frequently used
type of grid in hydrodynamic applications, the 5-decomposition often fails. In that
case, applying a different decomposition, viz. into 6 tetrahedra, has proven to be a
robust alternative. In unstructured grids consisting of hexahedral or tetrahedral cells,
it is only possible to perform particle tracing after the addition of connectivity information,
because it is not included. For this purpose, a library called CNX-lib was
developed.
It can be concluded from the examples in Chapter 3 and from the applications in
Chapter 6, that particle tracing is now possible in these special grid types. Particle tracing
was found to be a useful technique for exploring velocity fields, both when used
1 Strong, eternal and strong // is the huge row of the waves // and strong due to the eternal sea // was
the soft and fleeting wave. (Karin Boye: Havet)
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