Master's Thesis - Studierstube Augmented Reality Project - Graz ...

2.1 Technical Visualization
Figure 2.11: An exemplary color gradient for arbitrary parameter value mapping. A
gradient like this can even be used to suppress certain flow properties if for example an
appropriate transparency-value definition can be performed.
The main visualization techniques for any kind of flow data can be divided into four
main classes. A related taxonomy can be found in [Weiskopf2007] which we summarized
in figure 2.12. Furthermore some of these techniques are only valid or behave differently
for steady or unsteady flow and can thus be subdivided again. Steady flow refers in
this context to unchangeable vector fields and unsteady flow to changeable fields over
time.
• point-based direct flow visualization
implies that some fixed geometry is rendered for each velocity vector. A large
viewport showing enough of these representatives enables the observer to interpret
the whole vector field. The problem of visual clutter and occlusion is evident for
volumetric datasets.
• sparse particle tracing techniques
relies on calculations done based on the movement of massless particles injected
into the field and envelop everything from concrete particle effects to complex
trajectory integrations.
• dense particle tracing techniques
mostly rely on a specialized convolution of a texture with an even volumetric
flow field. Again, strategies to cope with visual clutter and occlusions have to be
investigated.
• feature based visualization approaches
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